Merge pull request #28 from erlware/next

Next

18 files changed, 1350 insertions, 410 deletions

diff --git a/src/rcl_app_discovery.erl b/src/rcl_app_discovery.erl
new file mode 100644
index 0000000..20df1cf
--- /dev/null
+++ b/src/rcl_app_discovery.erl
@@ -0,0 +1,223 @@
+%% -*- erlang-indent-level: 4; indent-tabs-mode: nil; fill-column: 80 -*-
+%%% Copyright 2012 Erlware, LLC. All Rights Reserved.
+%%%
+%%% This file is provided to you under the Apache License,
+%%% Version 2.0 (the "License"); you may not use this file
+%%% except in compliance with the License.  You may obtain
+%%% a copy of the License at
+%%%
+%%%   http://www.apache.org/licenses/LICENSE-2.0
+%%%
+%%% Unless required by applicable law or agreed to in writing,
+%%% software distributed under the License is distributed on an
+%%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+%%% KIND, either express or implied.  See the License for the
+%%% specific language governing permissions and limitations
+%%% under the License.
+%%%---------------------------------------------------------------------------
+%%% @author Eric Merritt <[email protected]>
+%%% @copyright (C) 2012 Erlware, LLC.
+%%%
+%%% @doc This provider uses the lib_dir setting of the state. It searches the
+%%% Lib Dirs looking for all OTP Applications that are available. When it finds
+%%% those OTP Applications it loads the information about them and adds them to
+%%% the state of available apps. This implements the rcl_provider behaviour.
+-module(rcl_app_discovery).
+
+-export([do/2,
+         format_error/1]).
+
+-include_lib("relcool/include/relcool.hrl").
+
+%%============================================================================
+%% API
+%%============================================================================
+
+%% @doc recursively dig down into the library directories specified in the state
+%% looking for OTP Applications
+-spec do(rcl_state:t(), [filename:name()]) -> {ok, [rcl_app_info:t()]} | relcool:error().
+do(State, LibDirs) ->
+    rcl_log:info(rcl_state:log(State),
+                 fun() ->
+                          ["Resolving OTP Applications from directories:\n",
+                           [[rcl_util:indent(1), LibDir, "\n"] || LibDir <- LibDirs]]
+                 end),
+    resolve_app_metadata(State, LibDirs).
+
+-spec format_error([ErrorDetail::term()]) -> iolist().
+format_error(ErrorDetails)
+  when erlang:is_list(ErrorDetails) ->
+    [[format_detail(ErrorDetail), "\n"] || ErrorDetail <- ErrorDetails].
+
+%%%===================================================================
+%%% Internal Functions
+%%%===================================================================
+resolve_app_metadata(State, LibDirs) ->
+    AppMeta0 = lists:flatten(ec_plists:map(fun(LibDir) ->
+                                               discover_dir([], LibDir)
+                                           end, LibDirs)),
+    AppMeta1 = setup_overrides(State, AppMeta0),
+
+    Errors = [case El of
+                  {error, Ret} -> Ret;
+                  _ -> El
+              end
+              || El <- AppMeta1,
+                 case El of
+                     {error, _} ->
+                         true;
+                     _ ->
+                         false
+                 end],
+
+    case Errors of
+        [] ->
+            AppMeta2 = lists:flatten(AppMeta1),
+            rcl_log:debug(rcl_state:log(State),
+                          fun() ->
+                                  ["Resolved the following OTP Applications from the system: \n",
+                                   [[rcl_app_info:format(1, App), "\n"] || App <- AppMeta2]]
+                          end),
+            {ok, AppMeta2};
+        _ ->
+            ?RCL_ERROR(Errors)
+    end.
+
+app_name({error, _}) ->
+    undefined;
+app_name(AppMeta) ->
+    rcl_app_info:name(AppMeta).
+
+setup_overrides(State, AppMetas0) ->
+    Overrides = rcl_state:overrides(State),
+    AppMetas1 = [AppMeta || AppMeta <- AppMetas0,
+                            not lists:keymember(app_name(AppMeta), 1, Overrides)],
+    [case is_valid_otp_app(filename:join([FileName, "ebin",
+                                         erlang:atom_to_list(AppName) ++ ".app"])) of
+         [] ->
+             {error, {invalid_override, AppName, FileName}};
+         Error = {error, _} ->
+             Error;
+         App ->
+             rcl_app_info:link(App, true)
+     end || {AppName, FileName} <- Overrides] ++ AppMetas1.
+
+
+
+-spec format_detail(ErrorDetail::term()) -> iolist().
+format_detail({error, {invalid_override, AppName, FileName}}) ->
+    io_lib:format("Override {~p, ~p} is not a valid OTP App. Perhaps you forgot to build it?",
+                  [AppName, FileName]);
+format_detail({accessing, File, eaccess}) ->
+    io_lib:format("permission denied accessing file ~s", [File]);
+format_detail({accessing, File, Type}) ->
+    io_lib:format("error (~p) accessing file ~s", [Type, File]);
+format_detail({no_beam_files, EbinDir}) ->
+    io_lib:format("no beam files found in directory ~s", [EbinDir]);
+format_detail({not_a_directory, EbinDir}) ->
+    io_lib:format("~s is not a directory when it should be a directory", [EbinDir]);
+format_detail({unable_to_load_app, AppDir, _}) ->
+    io_lib:format("Unable to load the application metadata from ~s", [AppDir]);
+format_detail({invalid_app_file, File}) ->
+    io_lib:format("Application metadata file exists but is malformed: ~s",
+                  [File]);
+format_detail({unversioned_app, AppDir, _AppName}) ->
+    io_lib:format("Application metadata exists but version is not available: ~s",
+                  [AppDir]);
+format_detail({app_info_error, {Module, Detail}}) ->
+    Module:format_error(Detail).
+
+-spec discover_dir([file:name()],
+                   file:name()) ->
+                          [rcl_app_info:t() | {error, Reason::term()}] |
+                          rcl_app_info:t() | {error, Reason::term()}.
+discover_dir(IgnoreDirs, File) ->
+    case (not lists:member(File, IgnoreDirs))
+        andalso filelib:is_dir(File) of
+        true ->
+            case file:list_dir(File) of
+                {error, Reason} ->
+                    {error, {accessing, File, Reason}};
+                {ok, List} ->
+                    ec_plists:map(fun(LibDir) ->
+                                     discover_dir(IgnoreDirs, LibDir)
+                                  end, [filename:join([File, Dir]) || Dir <- List])
+            end;
+        false ->
+            is_valid_otp_app(File)
+    end.
+
+-spec is_valid_otp_app(file:name()) -> rcl_app_info:t() | {error, Reason::term()} | [].
+is_valid_otp_app(File) ->
+    %% Is this an ebin dir?
+    EbinDir = filename:dirname(File),
+    case filename:basename(EbinDir) of
+        "ebin" ->
+            case lists:suffix(".app", File) of
+                true ->
+                    has_at_least_one_beam(EbinDir, File);
+                false ->
+                    []
+            end;
+        _ ->
+            []
+    end.
+
+-spec has_at_least_one_beam(file:name(), file:filename()) ->
+                                   rcl_app_info:t() | {error, Reason::term()}.
+has_at_least_one_beam(EbinDir, File) ->
+    case file:list_dir(EbinDir) of
+        {ok, List} ->
+            case lists:any(fun(NFile) -> lists:suffix(".beam", NFile) end, List) of
+                true ->
+                    gather_application_info(EbinDir, File);
+                false ->
+                    {error, {no_beam_files, EbinDir}}
+            end;
+        _ ->
+            {error, {not_a_directory, EbinDir}}
+    end.
+
+-spec gather_application_info(file:name(), file:filename()) ->
+                                     rcl_app_info:t() | {error, Reason::term()}.
+gather_application_info(EbinDir, File) ->
+    AppDir = filename:dirname(EbinDir),
+    case file:consult(File) of
+        {ok, [{application, AppName, AppDetail}]} ->
+            get_vsn(AppDir, AppName, AppDetail);
+        {error, Reason} ->
+            {error, {unable_to_load_app, AppDir, Reason}};
+        _ ->
+            {error, {invalid_app_file, File}}
+    end.
+
+-spec get_vsn(file:name(), atom(), proplists:proplist()) ->
+                     rcl_app_info:t() | {error, Reason::term()}.
+get_vsn(AppDir, AppName, AppDetail) ->
+    case proplists:get_value(vsn, AppDetail) of
+        undefined ->
+            {error, {unversioned_app, AppDir, AppName}};
+        AppVsn ->
+            case get_deps(AppDir, AppName, AppVsn, AppDetail) of
+                {ok, App} ->
+                    App;
+                {error, Detail} ->
+                    {error, {app_info_error, Detail}}
+            end
+    end.
+
+-spec get_deps(file:name(), atom(), string(), proplists:proplist()) ->
+                      {ok, rcl_app_info:t()} | {error, Reason::term()}.
+get_deps(AppDir, AppName, AppVsn, AppDetail) ->
+    ActiveApps = proplists:get_value(applications, AppDetail, []),
+    LibraryApps = proplists:get_value(included_applications, AppDetail, []),
+    rcl_app_info:new(AppName, AppVsn, AppDir, ActiveApps, LibraryApps).
+
+%%%===================================================================
+%%% Test Functions
+%%%===================================================================
+
+-ifndef(NOTEST).
+-include_lib("eunit/include/eunit.hrl").
+
+-endif.
diff --git a/src/rcl_app_info.erl b/src/rcl_app_info.erl
index bc64e30..f2afa0b 100644
--- a/src/rcl_app_info.erl
+++ b/src/rcl_app_info.erl
@@ -1,4 +1,4 @@
-%% -*- mode: Erlang; fill-column: 80; comment-column: 75; -*-
+%% -*- erlang-indent-level: 4; indent-tabs-mode: nil; fill-column: 80 -*-
 %%% Copyright 2012 Erlware, LLC. All Rights Reserved.
 %%%
 %%% This file is provided to you under the Apache License,
@@ -63,8 +63,8 @@
                      vsn :: ec_semver:semver(),
                      dir :: file:name(),
                      link=false :: boolean(),
-                     active_deps :: [atom()],
-                     library_deps :: [atom()]}).
+                     active_deps=[]:: [atom()],
+                     library_deps=[] :: [atom()]}).
 
 %%============================================================================
 %% types
diff --git a/src/rcl_cmd_args.erl b/src/rcl_cmd_args.erl
index 68bd9ce..bfb63b7 100644
--- a/src/rcl_cmd_args.erl
+++ b/src/rcl_cmd_args.erl
@@ -1,4 +1,4 @@
-%% -*- mode: Erlang; fill-column: 80; comment-column: 75; -*-
+%% -*- erlang-indent-level: 4; indent-tabs-mode: nil; fill-column: 80 -*-
 %%% Copyright 2012 Erlware, LLC. All Rights Reserved.
 %%%
 %%% This file is provided to you under the Apache License,
@@ -34,24 +34,28 @@
                         relcool:error().
 args2state({error, Detail}) ->
     ?RCL_ERROR({opt_parse, Detail});
-args2state({ok, {Opts, Targets}}) ->
+args2state({ok, {Opts, Target}})
+  when erlang:length(Target) == 0; erlang:length(Target) == 1 ->
     RelName = proplists:get_value(relname, Opts, undefined),
     RelVsn = proplists:get_value(relvsn, Opts, undefined),
-    case create_log(Opts,
-                    [{relname, RelName},
-                     {relvsn, RelVsn}]) of
-        Error = {error, _} ->
-            Error;
-        {ok, CommandLineConfig} ->
-            case validate_configs(Targets) of
+    case convert_target(Target) of
+        {ok, AtomizedTarget} ->
+            case create_log(Opts, [{relname, RelName},
+                                   {relvsn, RelVsn}]) of
                 Error = {error, _} ->
                     Error;
-                {ok, Configs} ->
-                    {ok, {rcl_state:new(CommandLineConfig, Configs), Configs}}
-            end
-    end.
+                {ok, CommandLineConfig} ->
+                    handle_config(Opts, AtomizedTarget, CommandLineConfig)
+            end;
+        Error ->
+            Error
+    end;
+args2state({ok, {_Opts, Targets}}) ->
+    ?RCL_ERROR({invalid_targets, Targets}).
 
 -spec format_error(Reason::term()) -> iolist().
+format_error({invalid_targets, Targets}) ->
+    io_lib:format("One config must be specified! not ~p~n", [Targets]);
 format_error({opt_parse, {invalid_option, Opt}}) ->
     io_lib:format("invalid option ~s~n", [Opt]);
 format_error({opt_parse, Arg}) ->
@@ -75,39 +79,51 @@ format_error({invalid_config_file, Config}) ->
     io_lib:format("Invalid configuration file specified: ~s", [Config]);
 format_error({failed_to_parse, Spec}) ->
     io_lib:format("Unable to parse spec ~s", [Spec]);
-format_error({unable_to_create_output_dir, OutputDir}) ->
-    io_lib:format("Unable to create output directory (possible permissions issue): ~s",
-                  [OutputDir]);
 format_error({not_directory, Dir}) ->
     io_lib:format("Library directory does not exist: ~s", [Dir]);
 format_error({invalid_log_level, LogLevel}) ->
     io_lib:format("Invalid log level specified -V ~p, log level must be in the"
-                  " range 0..2", [LogLevel]).
+                 " range 0..2", [LogLevel]);
+format_error({invalid_target, Target}) ->
+    io_lib:format("Invalid action specified: ~s", [Target]).
+
 
 %%%===================================================================
 %%% Internal Functions
 %%%===================================================================
--spec validate_configs([file:filename()]) ->
-                              {ok, [file:filename()]} | relcool:error().
-validate_configs(Configs) ->
-    Result =
-        lists:foldl(fun(_Config, Err = {error, _}) ->
-                            Err;
-                       (Config, Acc) ->
-                            case filelib:is_regular(Config) of
-                                true ->
-                                    [filename:absname(Config) | Acc];
-                                false ->
-                                    ?RCL_ERROR({invalid_config_file, Config})
-                            end
-                    end, [], Configs),
-    case Result of
-        {error, _} ->
-            Result;
-        _ ->
-            %% Order may be important so lets make sure they remain in the same
-            %% order they came in as
-            {ok, lists:reverse(Result)}
+-spec handle_config([getopt:option()], atom(), proplists:proplist()) ->
+                           {ok, {rcl_state:t(), [string()]}} |
+                           relcool:error().
+handle_config(Opts, Target, CommandLineConfig) ->
+    case validate_config(proplists:get_value(config, Opts, [])) of
+        Error = {error, _} ->
+            Error;
+        {ok, Config} ->
+            {ok, rcl_state:new([{config, Config} | CommandLineConfig], Target)}
+    end.
+
+-spec convert_target([string()]) -> {ok, release | relup} | relcool:error().
+convert_target([]) ->
+    {ok, release};
+convert_target(["release"]) ->
+    {ok, release};
+convert_target(["relup"]) ->
+    {ok, relup};
+convert_target(Target) ->
+    ?RCL_ERROR({invalid_target, Target}).
+
+-spec validate_config(file:filename() | undefined) ->
+                             {ok, file:filename() | undefined} | relcool:error().
+validate_config(undefined) ->
+    {ok, undefined};
+validate_config("") ->
+    {ok, undefined};
+validate_config(Config) ->
+    case filelib:is_regular(Config) of
+        true ->
+            {ok, filename:absname(Config)};
+        false ->
+            ?RCL_ERROR({invalid_config_file, Config})
     end.
 
 -spec create_log([getopt:option()], rcl_state:cmd_args()) ->
@@ -148,17 +164,7 @@ convert_goals([RawSpec | Rest], Acc) ->
                                {ok, rcl_state:cmd_args()} | relcool:error().
 create_output_dir(Opts, Acc) ->
     OutputDir = proplists:get_value(output_dir, Opts, "./_rel"),
-    case filelib:is_dir(OutputDir) of
-        false ->
-            case rcl_util:mkdir_p(OutputDir) of
-                ok ->
-                    create_lib_dirs(Opts, [{output_dir, OutputDir} | Acc]);
-                {error, _} ->
-                    ?RCL_ERROR({unable_to_create_output_dir, OutputDir})
-            end;
-        true ->
-            create_lib_dirs(Opts, [{output_dir, OutputDir} | Acc])
-    end.
+    create_lib_dirs(Opts, [{output_dir, filename:absname(OutputDir)} | Acc]).
 
 -spec create_lib_dirs([getopt:option()], rcl_state:cmd_args()) ->
                                {ok, rcl_state:cmd_args()} | relcool:error().
@@ -168,9 +174,27 @@ create_lib_dirs(Opts, Acc) ->
         Error = {error, _} ->
             Error;
         ok ->
-            {ok, [{lib_dirs, [filename:absname(Dir) || Dir <- Dirs]} | Acc]}
+            create_root_dir(Opts, [{lib_dirs, [filename:absname(Dir) || Dir <- Dirs]} | Acc])
+    end.
+
+-spec create_root_dir([getopt:option()], rcl_state:cmd_args()) ->
+                               {ok, rcl_state:cmd_args()} | relcool:error().
+create_root_dir(Opts, Acc) ->
+    Dir = proplists:get_value(root_dir, Opts, undefined),
+    case Dir of
+        undefined ->
+            {ok, Cwd} = file:get_cwd(),
+            create_disable_default_libs(Opts, [{root_dir, Cwd} | Acc]);
+        _ ->
+            create_disable_default_libs(Opts, [{root_dir, Dir} | Acc])
     end.
 
+-spec create_disable_default_libs([getopt:option()], rcl_state:cmd_args()) ->
+                                         {ok, rcl_state:cmd_args()} | relcool:error().
+create_disable_default_libs(Opts, Acc) ->
+    Def = proplists:get_value(disable_default_libs, Opts, false),
+    {ok, [{disable_default_libs, Def} | Acc]}.
+
 -spec check_lib_dirs([string()]) -> ok | relcool:error().
 check_lib_dirs([]) ->
     ok;
diff --git a/src/rcl_depsolver.erl b/src/rcl_depsolver.erl
index e74cf3b..0cf8c88 100644
--- a/src/rcl_depsolver.erl
+++ b/src/rcl_depsolver.erl
@@ -471,12 +471,13 @@ add_constraint(SrcPkg, SrcVsn, PkgsConstraints, PkgConstraint) ->
             {value, {PkgName, Constraints0}} ->
                 Constraints0
         end,
-    [{PkgName, [{PkgConstraint, {SrcPkg, SrcVsn}} | Constraints1]} |
-     lists:keydelete(PkgName, 1, PkgsConstraints)].
+    [{PkgName, [{PkgConstraint, {SrcPkg, SrcVsn}} | Constraints1]}
+    | lists:keydelete(PkgName, 1, PkgsConstraints)].
 
 %% @doc
 %% Extend the currently active constraints correctly for the given constraints.
--spec extend_constraints(pkg_name(), vsn(), constraints(),constraints()) -> [{pkg_name(), constraints()}].
+-spec extend_constraints(pkg_name(), vsn(), constraints(),constraints()) ->
+                                [{pkg_name(), constraints()}].
 extend_constraints(SrcPkg, SrcVsn, ExistingConstraints0, NewConstraints) ->
     lists:foldl(fun (Constraint, ExistingConstraints1) ->
                         add_constraint(SrcPkg, SrcVsn, ExistingConstraints1, Constraint)
diff --git a/src/rcl_goal_utils.erl b/src/rcl_goal_utils.erl
index 3627b9c..6065e5c 100644
--- a/src/rcl_goal_utils.erl
+++ b/src/rcl_goal_utils.erl
@@ -1,4 +1,4 @@
-%% -*- mode: Erlang; fill-column: 80; comment-column: 75; -*-
+%% -*- erlang-indent-level: 4; indent-tabs-mode: nil; fill-column: 80 -*-
 %%% Copyright 2012 Erlware, LLC. All Rights Reserved.
 %%%
 %%% This file is provided to you under the Apache License,
diff --git a/src/rcl_log.erl b/src/rcl_log.erl
index a5fb43a..71c0b5d 100644
--- a/src/rcl_log.erl
+++ b/src/rcl_log.erl
@@ -1,4 +1,4 @@
-%% -*- mode: Erlang; fill-column: 80; comment-column: 75; -*-
+%% -*- erlang-indent-level: 4; indent-tabs-mode: nil; fill-column: 80 -*-
 %%% Copyright 2012 Erlware, LLC. All Rights Reserved.
 %%%
 %%% This file is provided to you under the Apache License,
@@ -36,6 +36,7 @@
          format/1]).
 
 -export_type([int_log_level/0,
+              atom_log_level/0,
               log_level/0,
               log_fun/0,
               t/0]).
@@ -46,10 +47,14 @@
 %% types
 %%============================================================================
 
+-type log_level() :: int_log_level() | atom_log_level().
+
 -type int_log_level() :: 0..2.
+
 %% Why no warn? because for our purposes there is no difference between error
 %% and warn
--type log_level() :: error | info | debug.
+-type atom_log_level() :: error | info | debug.
+
 -opaque t() :: {?MODULE, int_log_level()}.
 
 -type log_fun() :: fun(() -> iolist()).
@@ -58,7 +63,7 @@
 %% API
 %%============================================================================
 %% @doc Create a new 'log level' for the system
--spec new(int_log_level() | log_level()) -> t().
+-spec new(log_level()) -> t().
 new(LogLevel) when LogLevel >= 0, LogLevel =< 2 ->
     {?MODULE, LogLevel};
 new(AtomLogLevel)
@@ -152,7 +157,7 @@ log_level({?MODULE, DetailLogLevel}) ->
     DetailLogLevel.
 
 %% @doc get the current log level as an atom
--spec atom_log_level(t()) -> log_level().
+-spec atom_log_level(t()) -> atom_log_level().
 atom_log_level({?MODULE, ?RCL_ERROR}) ->
     error;
 atom_log_level({?MODULE, ?RCL_INFO}) ->
diff --git a/src/rcl_provider.erl b/src/rcl_provider.erl
index c3ef434..750b96e 100644
--- a/src/rcl_provider.erl
+++ b/src/rcl_provider.erl
@@ -1,3 +1,19 @@
+%% -*- erlang-indent-level: 4; indent-tabs-mode: nil; fill-column: 80 -*-
+%%% Copyright 2012 Erlware, LLC. All Rights Reserved.
+%%%
+%%% This file is provided to you under the Apache License,
+%%% Version 2.0 (the "License"); you may not use this file
+%%% except in compliance with the License.  You may obtain
+%%% a copy of the License at
+%%%
+%%%   http://www.apache.org/licenses/LICENSE-2.0
+%%%
+%%% Unless required by applicable law or agreed to in writing,
+%%% software distributed under the License is distributed on an
+%%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+%%% KIND, either express or implied.  See the License for the
+%%% specific language governing permissions and limitations
+%%% under the License.
 %%%-------------------------------------------------------------------
 %%% @author Eric Merritt <[email protected]>
 %%% @copyright 2011 Erlware, LLC.
diff --git a/src/rcl_prv_assembler.erl b/src/rcl_prv_assembler.erl
index c0f65c9..63bd167 100644
--- a/src/rcl_prv_assembler.erl
+++ b/src/rcl_prv_assembler.erl
@@ -1,4 +1,4 @@
-%% -*- mode: Erlang; fill-column: 80; comment-column: 75; -*-
+%% -*- erlang-indent-level: 4; indent-tabs-mode: nil; fill-column: 80 -*-
 %%% Copyright 2012 Erlware, LLC. All Rights Reserved.
 %%%
 %%% This file is provided to you under the Apache License,
@@ -44,11 +44,16 @@ do(State) ->
     {RelName, RelVsn} = rcl_state:default_release(State),
     Release = rcl_state:get_release(State, RelName, RelVsn),
     OutputDir = rcl_state:output_dir(State),
-    case rcl_release:realized(Release) of
-        true ->
-            copy_app_directories_to_output(State, Release, OutputDir);
-        false ->
-            ?RCL_ERROR({unresolved_release, RelName, RelVsn})
+    case create_output_dir(OutputDir) of
+        ok ->
+            case rcl_release:realized(Release) of
+                true ->
+                    copy_app_directories_to_output(State, Release, OutputDir);
+                false ->
+                    ?RCL_ERROR({unresolved_release, RelName, RelVsn})
+            end;
+        Error ->
+            Error
     end.
 
 -spec format_error(ErrorDetail::term()) -> iolist().
@@ -69,13 +74,35 @@ format_error({release_script_generation_error, RelFile}) ->
 format_error({release_script_generation_warning, Module, Warnings}) ->
     ["Warnings generating release \s",
      rcl_util:indent(1), Module:format_warning(Warnings)];
+format_error({unable_to_create_output_dir, OutputDir}) ->
+    io_lib:format("Unable to create output directory (possible permissions issue): ~s",
+                  [OutputDir]);
 format_error({release_script_generation_error, Module, Errors}) ->
     ["Errors generating release \n",
-     rcl_util:indent(1), Module:format_error(Errors)].
+     rcl_util:indent(1), Module:format_error(Errors)];
+format_error({unable_to_make_symlink, AppDir, TargetDir, Reason}) ->
+    io_lib:format("Unable to symlink directory ~s to ~s because \n~s~s",
+                  [AppDir, TargetDir, rcl_util:indent(1),
+                   file:format_error(Reason)]).
 
 %%%===================================================================
 %%% Internal Functions
 %%%===================================================================
+-spec create_output_dir(file:name()) ->
+                               ok | {error, Reason::term()}.
+create_output_dir(OutputDir) ->
+    case filelib:is_dir(OutputDir) of
+        false ->
+            case rcl_util:mkdir_p(OutputDir) of
+                ok ->
+                    ok;
+                {error, _} ->
+                    ?RCL_ERROR({unable_to_create_output_dir, OutputDir})
+            end;
+        true ->
+            ok
+    end.
+
 copy_app_directories_to_output(State, Release, OutputDir) ->
     LibDir = filename:join([OutputDir, "lib"]),
     ok = ec_file:mkdir_p(LibDir),
@@ -85,9 +112,9 @@ copy_app_directories_to_output(State, Release, OutputDir) ->
                               (_) ->
                                    false
                            end,
-                           ec_plists:map(fun(App) ->
-                                                 copy_app(LibDir, App)
-                                         end, Apps)),
+                          lists:flatten(ec_plists:map(fun(App) ->
+                                                              copy_app(LibDir, App)
+                                                      end, Apps))),
     case Result of
         [E | _] ->
             E;
@@ -100,35 +127,65 @@ copy_app(LibDir, App) ->
     AppVsn = rcl_app_info:vsn_as_string(App),
     AppDir = rcl_app_info:dir(App),
     TargetDir = filename:join([LibDir, AppName ++ "-" ++ AppVsn]),
+    if
+        AppDir == TargetDir ->
+            %% No need to do anything here, discover found something already in
+            %% a release dir
+            ok;
+        true ->
+            copy_app(App, AppDir, TargetDir)
+    end.
+
+copy_app(App, AppDir, TargetDir) ->
+    remove_symlink_or_directory(TargetDir),
     case rcl_app_info:link(App) of
         true ->
-            file:make_symlink(AppDir, TargetDir);
+            link_directory(AppDir, TargetDir);
+        false ->
+            copy_directory(AppDir, TargetDir)
+    end.
+
+remove_symlink_or_directory(TargetDir) ->
+    case ec_file:is_symlink(TargetDir) of
+        true ->
+            ec_file:remove(TargetDir);
         false ->
-            ec_plists:map(fun(SubDir) ->
-                                  copy_dir(AppDir, TargetDir, SubDir)
-                          end, ["ebin",
-                                "include",
-                                "priv",
-                                "src",
-                                "c_src",
-                                "README",
-                                "LICENSE"])
+            case filelib:is_dir(TargetDir) of
+                true ->
+                    ok = ec_file:remove(TargetDir, [recursive]);
+                false ->
+                    ok
+            end
     end.
 
+link_directory(AppDir, TargetDir) ->
+    case file:make_symlink(AppDir, TargetDir) of
+        {error, Reason} ->
+            ?RCL_ERROR({unable_to_make_symlink, AppDir, TargetDir, Reason});
+        ok ->
+            ok
+    end.
+
+copy_directory(AppDir, TargetDir) ->
+    ec_plists:map(fun(SubDir) ->
+                          copy_dir(AppDir, TargetDir, SubDir)
+                  end, ["ebin",
+                        "include",
+                        "priv",
+                        "src",
+                        "c_src",
+                        "README",
+                        "LICENSE"]).
+
 copy_dir(AppDir, TargetDir, SubDir) ->
     SubSource = filename:join(AppDir, SubDir),
     SubTarget = filename:join(TargetDir, SubDir),
     case filelib:is_dir(SubSource) of
         true ->
-            case filelib:is_dir(SubTarget) of
-                true ->
-                    ok = ec_file:remove(SubTarget, [recursive]);
-                false ->
-                    ok
-            end,
+            ok = rcl_util:mkdir_p(SubTarget),
             case ec_file:copy(SubSource, SubTarget, [recursive]) of
                 {error, E} ->
-                    ?RCL_ERROR({ec_file_error, AppDir, TargetDir, E});
+                    ?RCL_ERROR({ec_file_error, AppDir, SubTarget, E});
                 ok ->
                     ok
             end;
@@ -144,7 +201,7 @@ create_release_info(State, Release, OutputDir) ->
                                     rcl_release:vsn(Release)]),
     ReleaseFile = filename:join([ReleaseDir, RelName ++ ".rel"]),
     ok = ec_file:mkdir_p(ReleaseDir),
-        case rcl_release:metadata(Release) of
+    case rcl_release:metadata(Release) of
         {ok, Meta} ->
                 ok = ec_file:write_term(ReleaseFile, Meta),
                 write_bin_file(State, Release, OutputDir, ReleaseDir);
@@ -163,11 +220,18 @@ write_bin_file(State, Release, OutputDir, RelDir) ->
     ErlOpts = rcl_state:get(State, erl_opts, ""),
     StartFile = bin_file_contents(RelName, RelVsn,
                                   rcl_release:erts(Release),
- ErlOpts),
-    ok = file:write_file(VsnRel, StartFile),
-    ok = file:change_mode(VsnRel, 8#777),
-    ok = file:write_file(BareRel, StartFile),
-    ok = file:change_mode(BareRel, 8#777),
+                                  ErlOpts),
+    %% We generate the start script by default, unless the user
+    %% tells us not too
+    case rcl_state:get(State, generate_start_script, true) of
+        false ->
+            ok;
+        _ ->
+            ok = file:write_file(VsnRel, StartFile),
+            ok = file:change_mode(VsnRel, 8#777),
+            ok = file:write_file(BareRel, StartFile),
+            ok = file:change_mode(BareRel, 8#777)
+    end,
     copy_or_generate_sys_config_file(State, Release, OutputDir, RelDir).
 
 %% @doc copy config/sys.config or generate one to releases/VSN/sys.config
diff --git a/src/rcl_prv_config.erl b/src/rcl_prv_config.erl
index ee1c770..60655b1 100644
--- a/src/rcl_prv_config.erl
+++ b/src/rcl_prv_config.erl
@@ -1,3 +1,19 @@
+%% -*- erlang-indent-level: 4; indent-tabs-mode: nil; fill-column: 80 -*-
+%%% Copyright 2012 Erlware, LLC. All Rights Reserved.
+%%%
+%%% This file is provided to you under the Apache License,
+%%% Version 2.0 (the "License"); you may not use this file
+%%% except in compliance with the License.  You may obtain
+%%% a copy of the License at
+%%%
+%%%   http://www.apache.org/licenses/LICENSE-2.0
+%%%
+%%% Unless required by applicable law or agreed to in writing,
+%%% software distributed under the License is distributed on an
+%%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+%%% KIND, either express or implied.  See the License for the
+%%% specific language governing permissions and limitations
+%%% under the License.
 %%%-------------------------------------------------------------------
 %%% @author Eric Merritt <[email protected]>
 %%% @copyright 2011 Erlware, LLC.
@@ -29,8 +45,12 @@ init(State) ->
 %% populating the state as a result.
 -spec do(rcl_state:t()) ->{ok,  rcl_state:t()} | relcool:error().
 do(State) ->
-    ConfigFiles = rcl_state:config_files(State),
-    lists:foldl(fun load_config/2, {ok, State}, ConfigFiles).
+    case rcl_state:config_file(State) of
+        undefined ->
+            search_for_dominating_config(State);
+        ConfigFile when erlang:is_list(ConfigFile) ->
+            load_config(ConfigFile, State)
+    end.
 
 -spec format_error(Reason::term()) -> iolist().
 format_error({consult, ConfigFile, Reason}) ->
@@ -42,11 +62,51 @@ format_error({invalid_term, Term}) ->
 %%%===================================================================
 %%% Internal Functions
 %%%===================================================================
--spec load_config(file:filename(), {ok, rcl_state:t()} | relcool:error()) ->
+search_for_dominating_config({ok, Cwd}) ->
+    ConfigFile = filename:join(Cwd, "relcool.config"),
+    case ec_file:exists(ConfigFile) of
+        true ->
+            {ok, ConfigFile};
+        false ->
+            search_for_dominating_config(parent_dir(Cwd))
+    end;
+search_for_dominating_config({error, _}) ->
+    no_config;
+search_for_dominating_config(State0) ->
+    {ok, Cwd} = file:get_cwd(),
+    case search_for_dominating_config({ok, Cwd}) of
+        {ok, Config} ->
+            %% we need to set the root dir on state as well
+            {ok, RootDir} = parent_dir(Config),
+            State1 = rcl_state:root_dir(State0, RootDir),
+            load_config(Config, rcl_state:config_file(State1, Config));
+        no_config ->
+            {ok, State0}
+    end.
+
+%% @doc Given a directory returns the name of the parent directory.
+-spec parent_dir(Filename::string()) ->
+                        {ok, DirName::string()} | {error, no_parent_dir}.
+parent_dir(Filename) ->
+    parent_dir(filename:split(Filename), []).
+
+%% @doc Given list of directories, splits the list and returns all dirs but the
+%%  last as a path.
+-spec parent_dir([string()], [string()]) ->
+                        {ok, DirName::string()} | {error, no_parent_dir}.
+parent_dir([_H], []) ->
+    {error, no_parent_dir};
+parent_dir([], []) ->
+    {error, no_parent_dir};
+parent_dir([_H], Acc) ->
+    {ok, filename:join(lists:reverse(Acc))};
+parent_dir([H | T], Acc) ->
+    parent_dir(T, [H | Acc]).
+
+
+-spec load_config(file:filename(), rcl_state:t()) ->
                          {ok, rcl_state:t()} | relcool:error().
-load_config(_, Err = {error, _}) ->
-    Err;
-load_config(ConfigFile, {ok, State}) ->
+load_config(ConfigFile, State) ->
     {ok, CurrentCwd} = file:get_cwd(),
     ok = file:set_cwd(filename:dirname(ConfigFile)),
     Result = case file:consult(ConfigFile) of
diff --git a/src/rcl_prv_discover.erl b/src/rcl_prv_discover.erl
index 0a12d24..2f88354 100644
--- a/src/rcl_prv_discover.erl
+++ b/src/rcl_prv_discover.erl
@@ -1,4 +1,4 @@
-%% -*- mode: Erlang; fill-column: 80; comment-column: 75; -*-
+%% -*- erlang-indent-level: 4; indent-tabs-mode: nil; fill-column: 80 -*-
 %%% Copyright 2012 Erlware, LLC. All Rights Reserved.
 %%%
 %%% This file is provided to you under the Apache License,
@@ -41,100 +41,60 @@ init(State) ->
 %% @doc recursively dig down into the library directories specified in the state
 %% looking for OTP Applications
 -spec do(rcl_state:t()) -> {ok, rcl_state:t()} | relcool:error().
-do(State) ->
-    OutputDir = rcl_state:output_dir(State),
-    LibDirs = get_lib_dirs(State),
-    rcl_log:info(rcl_state:log(State),
-                  fun() ->
-                          ["Resolving OTP Applications from directories:\n",
-                           [[rcl_util:indent(1), LibDir, "\n"] || LibDir <- LibDirs]]
-                  end),
-    resolve_app_metadata(State, LibDirs, OutputDir).
+do(State0) ->
+    LibDirs = get_lib_dirs(State0),
+    case rcl_app_discovery:do(State0, LibDirs) of
+        {ok, AppMeta} ->
+            case rcl_rel_discovery:do(State0, LibDirs, AppMeta) of
+                {ok, Releases} ->
+                    State1 = rcl_state:available_apps(State0, AppMeta),
+                    State3 = lists:foldl(fun add_if_not_found/2,
+                                         State1, Releases),
+                    {ok, State3};
+                Error ->
+                    Error
+            end;
+        Error ->
+            Error
+    end.
 
--spec format_error([ErrorDetail::term()]) -> iolist().
-format_error(ErrorDetails)
-  when erlang:is_list(ErrorDetails) ->
-    [[format_detail(ErrorDetail), "\n"] || ErrorDetail <- ErrorDetails].
+%% @doc this is here to comply with the signature. However, we do not actually
+%% produce any errors and so simply return an empty string.
+-spec format_error(any()) -> iolist().
+format_error(_) ->
+    "".
 
 %%%===================================================================
 %%% Internal Functions
 %%%===================================================================
-resolve_app_metadata(State, LibDirs, OutputDir) ->
-    AppMeta0 = lists:flatten(ec_plists:map(fun(LibDir) ->
-                                               discover_dir([OutputDir],
-                                                            LibDir)
-                                           end, LibDirs)),
-    AppMeta1 = setup_overrides(State, AppMeta0),
-
-    Errors = [case El of
-                  {error, Ret} -> Ret;
-                  _ -> El
-              end
-              || El <- AppMeta1,
-                 case El of
-                     {error, _} ->
-                         true;
-                     _ ->
-                         false
-                 end],
-
-    case Errors of
-        [] ->
-            AppMeta2 = lists:flatten(AppMeta1),
-            rcl_log:debug(rcl_state:log(State),
-                          fun() ->
-                                  ["Resolved the following OTP Applications from the system: \n",
-                                   [[rcl_app_info:format(1, App), "\n"] || App <- AppMeta2]]
-                          end),
-            {ok, rcl_state:available_apps(State, AppMeta2)};
-        _ ->
-            ?RCL_ERROR(Errors)
+%% @doc only add the release if its not documented in the system
+add_if_not_found(Rel, State) ->
+    RelName = rcl_release:name(Rel),
+    RelVsn = rcl_release:vsn(Rel),
+    try
+        rcl_state:get_release(State, RelName, RelVsn),
+        State
+    catch
+        throw:not_found ->
+            rcl_state:add_release(State, Rel)
     end.
 
-app_name({error, _}) ->
-    undefined;
-app_name(AppMeta) ->
-    rcl_app_info:name(AppMeta).
-
-setup_overrides(State, AppMetas0) ->
-    Overrides = rcl_state:overrides(State),
-    AppMetas1 = [AppMeta || AppMeta <- AppMetas0,
-                            not lists:keymember(app_name(AppMeta), 1, Overrides)],
-    [case is_valid_otp_app(filename:join([FileName, "ebin",
-                                         erlang:atom_to_list(AppName) ++ ".app"])) of
-         [] ->
-             {error, {invalid_override, AppName, FileName}};
-         Error = {error, _} ->
-             Error;
-         App ->
-             rcl_app_info:link(App, true)
-     end || {AppName, FileName} <- Overrides] ++ AppMetas1.
-
 get_lib_dirs(State) ->
     LibDirs0 = rcl_state:lib_dirs(State),
-    add_rebar_deps_dir(State, LibDirs0).
-
--spec add_rebar_deps_dir(rcl_state:t(), [file:name()]) -> [file:name()].
-add_rebar_deps_dir(State, LibDirs) ->
-    ExcludeRebar = rcl_state:get(State, discover_exclude_rebar, false),
-    case ExcludeRebar of
+    case rcl_state:get(State, disable_default_libs, false) of
         true ->
-            add_system_lib_dir(State, LibDirs);
+            LibDirs0;
         false ->
-            %% Check to see if there is a rebar.config. If so then look for a deps
-            %% dir. If both are there then we add that to the lib dirs.
-            {ok, Cwd} = file:get_cwd(),
-
-            RebarConfig = filename:join([Cwd, "rebar.config"]),
-            DepsDir = filename:join([Cwd, "deps"]),
-            case filelib:is_regular(RebarConfig) andalso filelib:is_dir(DepsDir) of
-                true ->
-                    add_system_lib_dir(State, [filename:absname(Cwd) | LibDirs]);
-                false ->
-                    add_system_lib_dir(State, LibDirs)
-            end
+            add_current_dir(State, LibDirs0)
     end.
 
+-spec add_current_dir(rcl_state:t(), [file:name()]) -> [file:name()].
+add_current_dir(State, LibDirs) ->
+    %% Check to see if there is a rebar.config. If so then look for a deps
+    %% dir. If both are there then we add that to the lib dirs.
+    Root = rcl_state:root_dir(State),
+    add_system_lib_dir(State, [filename:absname(Root) | LibDirs]).
+
 -spec add_system_lib_dir(rcl_state:t(), [file:name()]) -> [file:name()].
 add_system_lib_dir(State, LibDirs) ->
     ExcludeSystem = rcl_state:get(State, discover_exclude_system, false),
@@ -151,121 +111,3 @@ add_system_lib_dir(State, LibDirs) ->
                     LibDirs
             end
     end.
-
--spec format_detail(ErrorDetail::term()) -> iolist().
-format_detail({error, {invalid_override, AppName, FileName}}) ->
-    io_lib:format("Override {~p, ~p} is not a valid OTP App. Perhaps you forgot to build it?",
-                  [AppName, FileName]);
-format_detail({accessing, File, eaccess}) ->
-    io_lib:format("permission denied accessing file ~s", [File]);
-format_detail({accessing, File, Type}) ->
-    io_lib:format("error (~p) accessing file ~s", [Type, File]);
-format_detail({no_beam_files, EbinDir}) ->
-    io_lib:format("no beam files found in directory ~s", [EbinDir]);
-format_detail({not_a_directory, EbinDir}) ->
-    io_lib:format("~s is not a directory when it should be a directory", [EbinDir]);
-format_detail({unable_to_load_app, AppDir, _}) ->
-    io_lib:format("Unable to load the application metadata from ~s", [AppDir]);
-format_detail({invalid_app_file, File}) ->
-    io_lib:format("Application metadata file exists but is malformed: ~s",
-                  [File]);
-format_detail({unversioned_app, AppDir, _AppName}) ->
-    io_lib:format("Application metadata exists but version is not available: ~s",
-                  [AppDir]);
-format_detail({app_info_error, {Module, Detail}}) ->
-    Module:format_error(Detail).
-
--spec discover_dir([file:name()],
-                   file:name()) ->
-                          [rcl_app_info:t() | {error, Reason::term()}] |
-                          rcl_app_info:t() | {error, Reason::term()}.
-discover_dir(IgnoreDirs, File) ->
-    case (not lists:member(File, IgnoreDirs))
-        andalso filelib:is_dir(File) of
-        true ->
-            case file:list_dir(File) of
-                {error, Reason} ->
-                    {error, {accessing, File, Reason}};
-                {ok, List} ->
-                    ec_plists:map(fun(LibDir) ->
-                                     discover_dir(IgnoreDirs, LibDir)
-                                  end, [filename:join([File, Dir]) || Dir <- List])
-            end;
-        false ->
-            is_valid_otp_app(File)
-    end.
-
--spec is_valid_otp_app(file:name()) -> rcl_app_info:t() | {error, Reason::term()} | [].
-is_valid_otp_app(File) ->
-    %% Is this an ebin dir?
-    EbinDir = filename:dirname(File),
-    case filename:basename(EbinDir) of
-        "ebin" ->
-            case lists:suffix(".app", File) of
-                true ->
-                    has_at_least_one_beam(EbinDir, File);
-                false ->
-                    []
-            end;
-        _ ->
-            []
-    end.
-
--spec has_at_least_one_beam(file:name(), file:filename()) ->
-                                   rcl_app_info:t() | {error, Reason::term()}.
-has_at_least_one_beam(EbinDir, File) ->
-    case file:list_dir(EbinDir) of
-        {ok, List} ->
-            case lists:any(fun(NFile) -> lists:suffix(".beam", NFile) end, List) of
-                true ->
-                    gather_application_info(EbinDir, File);
-                false ->
-                    {error, {no_beam_files, EbinDir}}
-            end;
-        _ ->
-            {error, {not_a_directory, EbinDir}}
-    end.
-
--spec gather_application_info(file:name(), file:filename()) ->
-                                     rcl_app_info:t() | {error, Reason::term()}.
-gather_application_info(EbinDir, File) ->
-    AppDir = filename:dirname(EbinDir),
-    case file:consult(File) of
-        {ok, [{application, AppName, AppDetail}]} ->
-            get_vsn(AppDir, AppName, AppDetail);
-        {error, Reason} ->
-            {error, {unable_to_load_app, AppDir, Reason}};
-        _ ->
-            {error, {invalid_app_file, File}}
-    end.
-
--spec get_vsn(file:name(), atom(), proplists:proplist()) ->
-                     rcl_app_info:t() | {error, Reason::term()}.
-get_vsn(AppDir, AppName, AppDetail) ->
-    case proplists:get_value(vsn, AppDetail) of
-        undefined ->
-            {error, {unversioned_app, AppDir, AppName}};
-        AppVsn ->
-            case get_deps(AppDir, AppName, AppVsn, AppDetail) of
-                {ok, App} ->
-                    App;
-                {error, Detail} ->
-                    {error, {app_info_error, Detail}}
-            end
-    end.
-
--spec get_deps(file:name(), atom(), string(), proplists:proplist()) ->
-                      {ok, rcl_app_info:t()} | {error, Reason::term()}.
-get_deps(AppDir, AppName, AppVsn, AppDetail) ->
-    ActiveApps = proplists:get_value(applications, AppDetail, []),
-    LibraryApps = proplists:get_value(included_applications, AppDetail, []),
-    rcl_app_info:new(AppName, AppVsn, AppDir, ActiveApps, LibraryApps).
-
-%%%===================================================================
-%%% Test Functions
-%%%===================================================================
-
--ifndef(NOTEST).
--include_lib("eunit/include/eunit.hrl").
-
--endif.
diff --git a/src/rcl_prv_overlay.erl b/src/rcl_prv_overlay.erl
new file mode 100644
index 0000000..40471ea
--- /dev/null
+++ b/src/rcl_prv_overlay.erl
@@ -0,0 +1,418 @@
+%% -*- erlang-indent-level: 4; indent-tabs-mode: nil; fill-column: 80 -*-
+%%% Copyright 2012 Erlware, LLC. All Rights Reserved.
+%%%
+%%% This file is provided to you under the Apache License,
+%%% Version 2.0 (the "License"); you may not use this file
+%%% except in compliance with the License.  You may obtain
+%%% a copy of the License at
+%%%
+%%%   http://www.apache.org/licenses/LICENSE-2.0
+%%%
+%%% Unless required by applicable law or agreed to in writing,
+%%% software distributed under the License is distributed on an
+%%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+%%% KIND, either express or implied.  See the License for the
+%%% specific language governing permissions and limitations
+%%% under the License.
+%%%---------------------------------------------------------------------------
+%%% @author Eric Merritt <[email protected]>
+%%% @copyright (C) 2012 Erlware, LLC.
+%%%
+%%% @doc Given a complete built release this provider assembles that release
+%%% into a release directory.
+-module(rcl_prv_overlay).
+
+-behaviour(rcl_provider).
+
+-export([init/1,
+         do/1,
+         format_error/1]).
+
+-define(DIRECTORY_RE, ".*(\/|\\\\)$").
+
+-include_lib("relcool/include/relcool.hrl").
+
+%%============================================================================
+%% API
+%%============================================================================
+-spec init(rcl_state:t()) -> {ok, rcl_state:t()}.
+init(State) ->
+    {ok, State}.
+
+%% @doc recursively dig down into the library directories specified in the state
+%% looking for OTP Applications
+-spec do(rcl_state:t()) -> {ok, rcl_state:t()} | relcool:error().
+do(State) ->
+    {RelName, RelVsn} = rcl_state:default_release(State),
+    Release = rcl_state:get_release(State, RelName, RelVsn),
+    case rcl_release:realized(Release) of
+        true ->
+            generate_overlay_vars(State, Release);
+        false ->
+            ?RCL_ERROR({unresolved_release, RelName, RelVsn})
+    end.
+
+-spec format_error(ErrorDetail::term()) -> iolist().
+format_error({unresolved_release, RelName, RelVsn}) ->
+    io_lib:format("The release has not been resolved ~p-~s", [RelName, RelVsn]);
+format_error({ec_file_error, AppDir, TargetDir, E}) ->
+    io_lib:format("Unable to copy OTP App from ~s to ~s due to ~p",
+                  [AppDir, TargetDir, E]);
+format_error({unable_to_read_varsfile, FileName, Reason}) ->
+    io_lib:format("Unable to read vars file (~s) for overlay due to: ~p",
+                  [FileName, Reason]);
+format_error({overlay_failed, Errors}) ->
+    [[format_error(rcl_util:error_reason(Error)), "\n"] || Error <- Errors];
+format_error({dir_render_failed, Dir, Error}) ->
+    io_lib:format("rendering mkdir path failed ~s with ~p",
+                  [Dir, Error]);
+format_error({unable_to_make_symlink, AppDir, TargetDir, Reason}) ->
+    io_lib:format("Unable to symlink directory ~s to ~s because \n~s~s",
+                  [AppDir, TargetDir, rcl_util:indent(1),
+                   file:format_error(Reason)]);
+format_error({copy_failed, FromFile, ToFile, Err}) ->
+    io_lib:format("Unable to copy from ~s to ~s because of ~p",
+                  [FromFile, ToFile, Err]);
+format_error({unable_to_write, ToFile, Reason}) ->
+    io_lib:format("Unable to write to ~s because ~p",
+                  [ToFile, Reason]);
+format_error({unable_to_enclosing_dir, ToFile, Reason}) ->
+    io_lib:format("Unable to create enclosing directory for ~s because ~p",
+                  [ToFile, Reason]);
+format_error({unable_to_render_template, FromFile, Reason}) ->
+    io_lib:format("Unable to render template ~s because ~p",
+                  [FromFile, Reason]);
+format_error({unable_to_compile_template, FromFile, Reason}) ->
+    io_lib:format("Unable to compile template ~s because ~p",
+                  [FromFile, Reason]);
+format_error({unable_to_make_dir, Absolute, Error}) ->
+    io_lib:format("Unable to make directory ~s because ~p",
+                  [Absolute, Error]).
+
+%%%===================================================================
+%%% Internal Functions
+%%%===================================================================
+-spec generate_overlay_vars(rcl_state:t(), rcl_release:t()) ->
+                                   {ok, rcl_state:t()} | relcool:error().
+generate_overlay_vars(State, Release) ->
+    StateVars = generate_state_vars(State),
+    ReleaseVars = generate_release_vars(Release),
+    get_overlay_vars_from_file(State, StateVars ++ ReleaseVars).
+
+-spec get_overlay_vars_from_file(rcl_state:t(), proplists:proplist()) ->
+                                        {ok, rcl_state:t()} | relcool:error().
+get_overlay_vars_from_file(State, OverlayVars) ->
+    case rcl_state:get(State, overlay_vars, undefined) of
+        undefined ->
+            do_overlay(State, OverlayVars);
+        FileName ->
+            read_overlay_vars(State, OverlayVars, FileName)
+    end.
+
+-spec read_overlay_vars(rcl_state:t(), proplists:proplist(), file:name()) ->
+                                   {ok, rcl_state:t()} | relcool:error().
+read_overlay_vars(State, OverlayVars, FileName) ->
+    RelativeRoot = get_relative_root(State),
+    RelativePath = filename:join(RelativeRoot, erlang:iolist_to_binary(FileName)),
+    case file:consult(RelativePath) of
+        {ok, Terms} ->
+            case render_overlay_vars(OverlayVars, Terms, []) of
+                {ok, NewTerms} ->
+                    do_overlay(State, NewTerms ++ OverlayVars);
+                Error ->
+                    Error
+            end;
+        {error, Reason} ->
+            ?RCL_ERROR({unable_to_read_varsfile, FileName, Reason})
+    end.
+
+-spec render_overlay_vars(proplists:proplist(), proplists:proplist(),
+                         proplists:proplist()) ->
+                                 {ok, proplists:proplist()} | relcool:error().
+render_overlay_vars(OverlayVars, [{Key, Value} | Rest], Acc)
+  when erlang:is_list(Value) ->
+    case io_lib:printable_list(Value) of
+        true ->
+            case render_template(Acc ++ OverlayVars, erlang:iolist_to_binary(Value)) of
+                {ok, Data} ->
+                    %% Adding to the end sucks, but ordering needs to be retained
+                    render_overlay_vars(OverlayVars, Rest, Acc ++ [{Key, Data}]);
+                Error ->
+                    Error
+            end;
+        false ->
+            case render_overlay_vars(Acc ++ OverlayVars, Value, []) of
+                {ok, NewValue} ->
+                    render_overlay_vars(OverlayVars, Rest, Acc ++ [{Key, NewValue}]);
+                Error ->
+                    Error
+            end
+    end;
+render_overlay_vars(OverlayVars, [{Key, Value} | Rest], Acc)
+  when erlang:is_binary(Value) ->
+    case render_template(Acc ++ OverlayVars, erlang:iolist_to_binary(Value)) of
+        {ok, Data} ->
+            render_overlay_vars(OverlayVars, Rest, Acc ++ [{Key, erlang:iolist_to_binary(Data)}]);
+        Error ->
+            Error
+    end;
+render_overlay_vars(OverlayVars, [KeyValue | Rest], Acc) ->
+    render_overlay_vars(OverlayVars, Rest, Acc ++ [KeyValue]);
+render_overlay_vars(_OverlayVars, [], Acc) ->
+    {ok, Acc}.
+
+-spec generate_release_vars(rcl_release:t()) -> proplists:proplist().
+generate_release_vars(Release) ->
+    [{erts_vsn, rcl_release:erts(Release)},
+     {release_erts_version, rcl_release:erts(Release)},
+     {release_name, rcl_release:name(Release)},
+     {rel_vsn, rcl_release:vsn(Release)},
+     {release_version, rcl_release:vsn(Release)},
+     {release_applications, lists:map(fun(App) ->
+                                              rcl_app_info:name(App)
+                                        end, rcl_release:application_details(Release))},
+    {release, [generate_app_vars(App)|| App <- rcl_release:application_details(Release)]},
+     {release_goals,   [if
+                            erlang:is_list(Constraint) ->
+                                Constraint;
+                            true ->
+                                rcl_depsolver:format_constraint(Constraint)
+                        end || Constraint <- rcl_release:goals(Release)]}].
+
+-spec generate_app_vars(rcl_app_info:t()) -> AppInfo::tuple().
+generate_app_vars(App) ->
+    {rcl_app_info:name(App),
+     [{version, rcl_app_info:vsn_as_string(App)},
+      {dir, rcl_app_info:dir(App)},
+      {active_dependencies, rcl_app_info:active_deps(App)},
+      {library_dependencies, rcl_app_info:library_deps(App)},
+      {link, rcl_app_info:link(App)}]}.
+
+-spec generate_state_vars(rcl_state:t()) -> proplists:proplist().
+generate_state_vars(State) ->
+    [{log, rcl_log:format(rcl_state:log(State))},
+     {output_dir, rcl_state:output_dir(State)},
+     {target_dir, rcl_state:output_dir(State)},
+     {overridden, [AppName || {AppName, _} <- rcl_state:overrides(State)]},
+     {overrides, rcl_state:overrides(State)},
+     {goals, [rcl_depsolver:format_constraint(Constraint) ||
+                 Constraint <- rcl_state:goals(State)]},
+     {lib_dirs, rcl_state:lib_dirs(State)},
+     {config_file, rcl_state:config_file(State)},
+     {providers, rcl_state:providers(State)},
+     {sys_config, rcl_state:sys_config(State)},
+     {root_dir, rcl_state:root_dir(State)},
+     {default_release_name, case rcl_state:default_release(State) of
+                                {Name0, _} ->
+                                    Name0
+                            end},
+     {default_release_version, case rcl_state:default_release(State) of
+                                   {_, Vsn0} ->
+                                       Vsn0
+                               end},
+     {default_release, case rcl_state:default_release(State) of
+                           {Name1, undefined} ->
+                               erlang:atom_to_list(Name1);
+                           {Name1, Vsn1} ->
+                               erlang:atom_to_list(Name1) ++ "-" ++ Vsn1
+                       end}].
+
+-spec do_overlay(rcl_state:t(), proplists:proplist()) ->
+                                   {ok, rcl_state:t()} | relcool:error().
+do_overlay(State, OverlayVars) ->
+    case rcl_state:get(State, overlay, undefined) of
+        undefined ->
+            {ok, State};
+        Overlays ->
+            handle_errors(State,
+                          lists:map(fun(Overlay) ->
+                                            do_individual_overlay(State, OverlayVars,
+                                                                  Overlay)
+                                    end, Overlays))
+    end.
+
+-spec handle_errors(rcl_state:t(), [ok | relcool:error()]) ->
+                           {ok, rcl_state:t()} | relcool:error().
+handle_errors(State, Result) ->
+    case [Error || Error <- Result,
+                   rcl_util:is_error(Error)] of
+        Errors = [_|_] ->
+            ?RCL_ERROR({overlay_failed, Errors});
+        [] ->
+            {ok, State}
+    end.
+
+-spec do_individual_overlay(rcl_state:t(), proplists:proplist(),
+                            OverlayDirective::term()) ->
+                                   {ok, rcl_state:t()} | relcool:error().
+do_individual_overlay(State, OverlayVars, {mkdir, Dir}) ->
+    ModuleName = make_template_name("rcl_mkdir_template", Dir),
+    case erlydtl:compile(erlang:iolist_to_binary(Dir), ModuleName) of
+        {ok, ModuleName} ->
+            case render(ModuleName, OverlayVars) of
+                {ok, IoList} ->
+                    Absolute = absolutize(State,
+                                          filename:join(rcl_state:output_dir(State),
+                                                        erlang:iolist_to_binary(IoList))),
+                    case rcl_util:mkdir_p(Absolute) of
+                        {error, Error} ->
+                            ?RCL_ERROR({unable_to_make_dir, Absolute, Error});
+                        ok ->
+                            ok
+                    end;
+                {error, Error} ->
+                    ?RCL_ERROR({dir_render_failed, Dir, Error})
+            end;
+        {error, Reason} ->
+            ?RCL_ERROR({unable_to_compile_template, Dir, Reason})
+    end;
+do_individual_overlay(State, OverlayVars, {copy, From, To}) ->
+    FromTemplateName = make_template_name("rcl_copy_from_template", From),
+    ToTemplateName = make_template_name("rcl_copy_to_template", To),
+    file_render_do(OverlayVars, From, FromTemplateName,
+                   fun(FromFile) ->
+                           file_render_do(OverlayVars, To, ToTemplateName,
+                                          fun(ToFile) ->
+                                                  copy_to(State, FromFile, ToFile)
+                                          end)
+                   end);
+do_individual_overlay(State, OverlayVars, {template, From, To}) ->
+    FromTemplateName = make_template_name("rcl_template_from_template", From),
+    ToTemplateName = make_template_name("rcl_template_to_template", To),
+    file_render_do(OverlayVars, From, FromTemplateName,
+                   fun(FromFile) ->
+                           file_render_do(OverlayVars, To, ToTemplateName,
+                                          fun(ToFile) ->
+                                                  RelativeRoot = get_relative_root(State),
+                                                  FromFile0 = absolutize(State,
+                                                                         filename:join(RelativeRoot,
+                                                                                       erlang:iolist_to_binary(FromFile))),
+                                                  FromFile1 = erlang:binary_to_list(FromFile0),
+                                                  write_template(OverlayVars,
+                                                                 FromFile1,
+                                                                 absolutize(State,
+                                                                            filename:join(rcl_state:output_dir(State),
+                                                                                          erlang:iolist_to_binary(ToFile))))
+                                          end)
+                   end).
+
+-spec copy_to(rcl_state:t(), file:name(), file:name()) -> ok | relcool:error().
+copy_to(State, FromFile0, ToFile0) ->
+    RelativeRoot = get_relative_root(State),
+    ToFile1 = absolutize(State, filename:join(rcl_state:output_dir(State),
+                                              erlang:iolist_to_binary(ToFile0))),
+
+    FromFile1 = absolutize(State, filename:join(RelativeRoot,
+                                                erlang:iolist_to_binary(FromFile0))),
+    ToFile2 = case is_directory(ToFile0, ToFile1) of
+                  false ->
+                      filelib:ensure_dir(ToFile1),
+                      ToFile1;
+                  true ->
+                      rcl_util:mkdir_p(ToFile1),
+                      erlang:iolist_to_binary(filename:join(ToFile1,
+                                                            filename:basename(FromFile1)))
+              end,
+    case ec_file:copy(FromFile1, ToFile2) of
+        ok ->
+            {ok, FileInfo} = file:read_file_info(FromFile1),
+            ok = file:write_file_info(ToFile2, FileInfo),
+            ok;
+        {error, Err} ->
+            ?RCL_ERROR({copy_failed,
+                        FromFile1,
+                        ToFile1, Err})
+    end.
+
+get_relative_root(State) ->
+    case rcl_state:config_file(State) of
+        [] ->
+            rcl_state:root_dir(State);
+        Config ->
+            filename:dirname(Config)
+    end.
+
+-spec is_directory(file:name(), file:name()) -> boolean().
+is_directory(ToFile0, ToFile1) ->
+    case re:run(ToFile0, ?DIRECTORY_RE) of
+        nomatch ->
+            filelib:is_dir(ToFile1);
+        _ ->
+            true
+    end.
+
+
+-spec render_template(proplists:proplist(), iolist()) ->
+                             ok | relcool:error().
+render_template(OverlayVars, Data) ->
+    TemplateName = make_template_name("rcl_template_renderer", Data),
+    case erlydtl:compile(Data, TemplateName) of
+        Good when Good =:= ok; Good =:= {ok, TemplateName} ->
+            case render(TemplateName, OverlayVars) of
+                {ok, IoData} ->
+                    {ok, IoData};
+                {error, Reason} ->
+                    ?RCL_ERROR({unable_to_render_template, Data, Reason})
+            end;
+        {error, Reason} ->
+            ?RCL_ERROR({unable_to_compile_template, Data, Reason})
+    end.
+
+write_template(OverlayVars, FromFile, ToFile) ->
+    case render_template(OverlayVars, FromFile) of
+        {ok, IoData} ->
+            case filelib:ensure_dir(ToFile) of
+                ok ->
+                    case file:write_file(ToFile, IoData) of
+                        ok ->
+                            {ok, FileInfo} = file:read_file_info(FromFile),
+                            ok = file:write_file_info(ToFile, FileInfo),
+                            ok;
+                        {error, Reason} ->
+                            ?RCL_ERROR({unable_to_write, ToFile, Reason})
+                    end;
+                {error, Reason} ->
+                    ?RCL_ERROR({unable_to_enclosing_dir, ToFile, Reason})
+            end;
+        Error ->
+            Error
+    end.
+
+-spec file_render_do(proplists:proplist(), iolist(), module(),
+                     fun((term()) -> {ok, rcl_state:t()} | relcool:error())) ->
+                            {ok, rcl_state:t()} | relcool:error().
+file_render_do(OverlayVars, Data, TemplateName, NextAction) ->
+    case erlydtl:compile(erlang:iolist_to_binary(Data), TemplateName) of
+        {ok, TemplateName} ->
+            case render(TemplateName, OverlayVars) of
+                {ok, IoList} ->
+                    NextAction(IoList);
+                {error, Error} ->
+                    ?RCL_ERROR({render_failed, Data, Error})
+            end;
+        {error, Reason} ->
+            ?RCL_ERROR({unable_to_compile_template, Data, Reason})
+    end.
+
+-spec make_template_name(string(), term()) -> module().
+make_template_name(Base, Value) ->
+    %% Seed so we get different values each time
+    random:seed(erlang:now()),
+    Hash = erlang:phash2(Value),
+    Ran = random:uniform(10000000),
+    erlang:list_to_atom(Base ++ "_" ++
+                            erlang:integer_to_list(Hash) ++
+                            "_" ++ erlang:integer_to_list(Ran)).
+
+-spec render(module(), proplists:proplist()) -> {ok, iolist()} | {error, Reason::term()}.
+render(ModuleName, OverlayVars) ->
+    try
+        ModuleName:render(OverlayVars)
+    catch
+        _:Reason ->
+            {error, Reason}
+    end.
+
+absolutize(State, FileName) ->
+    filename:absname(filename:join(rcl_state:root_dir(State),
+                                   erlang:iolist_to_binary(FileName))).
diff --git a/src/rcl_prv_release.erl b/src/rcl_prv_release.erl
index 66f4e11..eac1f20 100644
--- a/src/rcl_prv_release.erl
+++ b/src/rcl_prv_release.erl
@@ -1,4 +1,4 @@
-%% -*- mode: Erlang; fill-column: 80; comment-column: 75; -*-
+%% -*- erlang-indent-level: 4; indent-tabs-mode: nil; fill-column: 80 -*-
 %%% Copyright 2012 Erlware, LLC. All Rights Reserved.
 %%%
 %%% This file is provided to you under the Apache License,
@@ -47,6 +47,8 @@ do(State) ->
     find_default_release(State, DepGraph).
 
 -spec format_error(ErrorDetail::term()) -> iolist().
+format_error(no_goals_specified) ->
+    "No goals specified for this release ~n";
 format_error({no_release_name, Vsn}) ->
     io_lib:format("A target release version was specified (~s) but no name", [Vsn]);
 format_error({invalid_release_info, Info}) ->
@@ -99,36 +101,25 @@ find_default_release(State, DepGraph) ->
     end.
 
 resolve_default_release(State0, DepGraph) ->
-    %% Here we will just get the lastest version and run that.
+    %% Here we will just get the highest versioned release and run that.
     case lists:sort(fun release_sort/2,
                     ec_dictionary:to_list(rcl_state:releases(State0))) of
-        All = [{{RelName, RelVsn}, _} | _] ->
+        [{{RelName, RelVsn}, _} | _] ->
             State1 = rcl_state:default_release(State0, RelName, RelVsn),
-            lists:foldl(fun({{RN, RV}, _}, {ok, State2}) ->
-                                solve_release(State2,
-                                              DepGraph, RN, RV);
-                           (_, E) ->
-                                E
-                        end, {ok, State1}, All);
+            solve_release(State1, DepGraph, RelName, RelVsn);
         [] ->
             ?RCL_ERROR(no_releases_in_system)
     end.
 
-
 resolve_default_version(State0, DepGraph, RelName) ->
     %% Here we will just get the lastest version and run that.
     AllReleases = ec_dictionary:to_list(rcl_state:releases(State0)),
     SpecificReleases = [Rel || Rel={{PossibleRelName, _}, _} <- AllReleases,
                                PossibleRelName =:= RelName],
     case lists:sort(fun release_sort/2, SpecificReleases) of
-        All = [{{RelName, RelVsn}, _} | _] ->
+        [{{RelName, RelVsn}, _} | _] ->
             State1 = rcl_state:default_release(State0, RelName, RelVsn),
-            lists:foldl(fun({RN, RV}, {ok, State2}) ->
-                                solve_release(State2,
-                                              DepGraph, RN, RV);
-                           (_, E) ->
-                                E
-                        end, {ok, State1}, All);
+            solve_release(State1, DepGraph, RelName, RelVsn);
         [] ->
             ?RCL_ERROR({no_releases_for, RelName})
     end.
@@ -148,14 +139,22 @@ release_sort({{RelNameA, RelVsnA}, _}, {{RelNameB, RelVsnB}, _}) ->
         ec_semver:lte(RelVsnA, RelVsnB).
 
 solve_release(State0, DepGraph, RelName, RelVsn) ->
+    rcl_log:debug(rcl_state:log(State0),
+                  "Solving Release ~p-~s~n",
+                  [RelName, RelVsn]),
     try
         Release = rcl_state:get_release(State0, RelName, RelVsn),
         Goals = rcl_release:goals(Release),
-        case rcl_depsolver:solve(DepGraph, Goals) of
-            {ok, Pkgs} ->
-                set_resolved(State0, Release, Pkgs);
-            {error, Error} ->
-                ?RCL_ERROR({failed_solve, Error})
+        case Goals of
+            [] ->
+                ?RCL_ERROR(no_goals_specified);
+            _ ->
+                case rcl_depsolver:solve(DepGraph, Goals) of
+                    {ok, Pkgs} ->
+                        set_resolved(State0, Release, Pkgs);
+                    {error, Error} ->
+                        ?RCL_ERROR({failed_solve, Error})
+                end
         end
     catch
         throw:not_found ->
@@ -169,7 +168,7 @@ set_resolved(State, Release0, Pkgs) ->
                         "Resolved ~p-~s~n",
                         [rcl_release:name(Release1),
                          rcl_release:vsn(Release1)]),
-           rcl_log:info(rcl_state:log(State),
+           rcl_log:debug(rcl_state:log(State),
                          fun() ->
                                  rcl_release:format(1, Release1)
                          end),
diff --git a/src/rcl_rel_discovery.erl b/src/rcl_rel_discovery.erl
new file mode 100644
index 0000000..0f923a0
--- /dev/null
+++ b/src/rcl_rel_discovery.erl
@@ -0,0 +1,166 @@
+%% -*- erlang-indent-level: 4; indent-tabs-mode: nil; fill-column: 80 -*-
+%%% Copyright 2012 Erlware, LLC. All Rights Reserved.
+%%%
+%%% This file is provided to you under the Apache License,
+%%% Version 2.0 (the "License"); you may not use this file
+%%% except in compliance with the License.  You may obtain
+%%% a copy of the License at
+%%%
+%%%   http://www.apache.org/licenses/LICENSE-2.0
+%%%
+%%% Unless required by applicable law or agreed to in writing,
+%%% software distributed under the License is distributed on an
+%%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+%%% KIND, either express or implied.  See the License for the
+%%% specific language governing permissions and limitations
+%%% under the License.
+%%%---------------------------------------------------------------------------
+%%% @author Eric Merritt <[email protected]>
+%%% @copyright (C) 2012 Erlware, LLC.
+%%%
+%%% @doc This provider uses the lib_dir setting of the state. It searches the
+%%% Lib Dirs looking for all OTP Applications that are available. When it finds
+%%% those OTP Applications it loads the information about them and adds them to
+%%% the state of available apps. This implements the rcl_provider behaviour.
+-module(rcl_rel_discovery).
+
+-export([do/3,
+         format_error/1]).
+
+-include_lib("relcool/include/relcool.hrl").
+
+%%============================================================================
+%% API
+%%============================================================================
+
+%% @doc recursively dig down into the library directories specified in the state
+%% looking for OTP Applications
+-spec do(rcl_state:t(), [filename:name()], [rcl_app_info:t()]) ->
+                {ok, [rcl_release:t()]} | relcool:error().
+do(State, LibDirs, AppMeta) ->
+    rcl_log:info(rcl_state:log(State),
+                 fun() ->
+                         ["Resolving available releases from directories:\n",
+                          [[rcl_util:indent(1), LibDir, "\n"] || LibDir <- LibDirs]]
+                 end),
+    resolve_rel_metadata(State, LibDirs, AppMeta).
+
+-spec format_error([ErrorDetail::term()]) -> iolist().
+format_error(ErrorDetails)
+  when erlang:is_list(ErrorDetails) ->
+    [[format_detail(ErrorDetail), "\n"] || ErrorDetail <- ErrorDetails].
+
+%%%===================================================================
+%%% Internal Functions
+%%%===================================================================
+resolve_rel_metadata(State, LibDirs, AppMeta) ->
+    ReleaseMeta0 =
+        lists:flatten(ec_plists:map(fun(LibDir) ->
+                                            discover_dir([], LibDir, AppMeta)
+                                    end, LibDirs)),
+    Errors = [case El of
+                  {error, Ret} -> Ret;
+                  _ -> El
+              end
+              || El <- ReleaseMeta0,
+                 case El of
+                     {error, _} ->
+                         true;
+                     _ ->
+                         false
+                 end],
+
+    case Errors of
+        [] ->
+            ReleaseMeta1 = lists:flatten(ReleaseMeta0),
+            rcl_log:debug(rcl_state:log(State),
+                          fun() ->
+                                  ["Resolved the following OTP Releases from the system: \n",
+                                   [[rcl_release:format(1, Rel), "\n"] || Rel <- ReleaseMeta1]]
+                          end),
+            {ok, ReleaseMeta1};
+        _ ->
+            ?RCL_ERROR(Errors)
+    end.
+
+-spec format_detail(ErrorDetail::term()) -> iolist().
+format_detail({accessing, File, eaccess}) ->
+    io_lib:format("permission denied accessing file ~s", [File]);
+format_detail({accessing, File, Type}) ->
+    io_lib:format("error (~p) accessing file ~s", [Type, File]).
+
+-spec discover_dir([file:name()], file:name(), [rcl_app_info:t()]) ->
+        [rcl_release:t() | {error, Reason::term()}]
+      | rcl_release:t()
+      | {error, Reason::term()}.
+discover_dir(IgnoreDirs, File, AppMeta) ->
+    case (not lists:member(File, IgnoreDirs))
+        andalso filelib:is_dir(File) of
+        true ->
+            case file:list_dir(File) of
+                {error, Reason} ->
+                    {error, {accessing, File, Reason}};
+                {ok, List} ->
+                    ec_plists:map(fun(LibDir) ->
+                                          discover_dir(IgnoreDirs, LibDir, AppMeta)
+                                  end,
+                                 [filename:join([File, Dir]) || Dir <- List])
+            end;
+        false ->
+            is_valid_release(File, AppMeta)
+    end.
+
+-spec is_valid_release(file:name(),
+                       [rcl_app_info:t()]) ->
+        rcl_release:t()
+      | {error, Reason::term()}
+      | [].
+is_valid_release(File, AppMeta) ->
+    case lists:suffix(".rel", File) of
+        true ->
+            resolve_release(File, AppMeta);
+        false ->
+            []
+    end.
+
+resolve_release(RelFile, AppMeta) ->
+    case file:consult(RelFile) of
+        {ok, [{release, {RelName, RelVsn},
+               {erts, ErtsVsn},
+               Apps}]} ->
+            build_release(RelName, RelVsn, ErtsVsn, Apps, AppMeta);
+        {ok, InvalidRelease} ->
+            ?RCL_ERROR({invalid_release_information, InvalidRelease});
+        {error, Reason} ->
+            ?RCL_ERROR({unable_to_read, RelFile, Reason})
+    end.
+
+build_release(RelName, RelVsn, ErtsVsn, Apps, AppMeta) ->
+    Release = rcl_release:erts(rcl_release:new(RelName, RelVsn),
+                               ErtsVsn),
+    resolve_apps(Apps, AppMeta, Release, []).
+
+resolve_apps([], _AppMeta, Release, Acc) ->
+    rcl_release:application_details(Release, Acc);
+resolve_apps([AppInfo | Apps], AppMeta, Release, Acc) ->
+    AppName = erlang:element(1, AppInfo),
+    AppVsn = ec_semver:parse(erlang:element(2, AppInfo)),
+    case find_app(AppName, AppVsn, AppMeta) of
+        Error = {error, _} ->
+            Error;
+        ResolvedApp ->
+            resolve_apps(Apps, AppMeta, Release, [ResolvedApp | Acc])
+    end.
+
+find_app(AppName, AppVsn, AppMeta) ->
+    case ec_lists:find(fun(App) ->
+                               NAppName = rcl_app_info:name(App),
+                               NAppVsn = rcl_app_info:vsn(App),
+                               AppName == NAppName andalso
+                                   AppVsn == NAppVsn
+                       end, AppMeta) of
+        {ok, Head} ->
+            Head;
+        error ->
+            ?RCL_ERROR({could_not_find, {AppName, AppVsn}})
+    end.
diff --git a/src/rcl_release.erl b/src/rcl_release.erl
index aa5de72..97465d0 100644
--- a/src/rcl_release.erl
+++ b/src/rcl_release.erl
@@ -1,4 +1,4 @@
-%% -*- mode: Erlang; fill-column: 80; comment-column: 75; -*-
+%% -*- erlang-indent-level: 4; indent-tabs-mode: nil; fill-column: 80 -*-
 %%% Copyright 2012 Erlware, LLC. All Rights Reserved.
 %%%
 %%% This file is provided to you under the Apache License,
@@ -32,6 +32,7 @@
          realize/3,
          applications/1,
          application_details/1,
+         application_details/2,
          realized/1,
          metadata/1,
          format/1,
@@ -72,7 +73,7 @@
                             {app_name(), app_vsn(), app_type() | incl_apps()} |
                             {app_name(), app_vsn(), app_type(), incl_apps()}.
 
--type application_constraint() :: rcl_depsolver:constraint() | string() | binary().
+-type application_constraint() :: rcl_depsolver:raw_constraint() | string() | binary().
 -type application_goal() :: application_constraint()
                           | {application_constraint(), app_type() | incl_apps()}
                           | {application_constraint(), app_type(), incl_apps() | none}.
@@ -88,7 +89,7 @@
 %%============================================================================
 -spec new(atom(), string()) -> t().
 new(ReleaseName, ReleaseVsn) ->
-    #release_t{name=ReleaseName, vsn=ReleaseVsn,
+    #release_t{name=to_atom(ReleaseName), vsn=ReleaseVsn,
                annotations=ec_dictionary:new(ec_dict)}.
 
 -spec name(t()) -> atom().
@@ -134,12 +135,18 @@ applications(#release_t{applications=Apps}) ->
     Apps.
 
 %% @doc this gives the rcl_app_info objects representing the applications in
-%% this release. These can only be populated by the 'realize' call in this
-%% module.
+%% this release. These should only be populated by the 'realize' call in this
+%% module or by reading an existing rel file.
 -spec application_details(t()) -> [rcl_app_info:t()].
 application_details(#release_t{app_detail=App}) ->
     App.
 
+%% @doc this is only expected to be called by a process building a new release
+%% from an existing rel file.
+-spec application_details(t(), [rcl_app_info:t()]) -> t().
+application_details(Release, AppDetail) ->
+    Release#release_t{app_detail=AppDetail}.
+
 -spec realized(t()) -> boolean().
 realized(#release_t{realized=Realized}) ->
     Realized.
@@ -163,7 +170,7 @@ format(Release) ->
 format(Indent, #release_t{name=Name, vsn=Vsn, erts=ErtsVsn, realized=Realized,
                          goals = Goals, applications=Apps}) ->
     BaseIndent = rcl_util:indent(Indent),
-    [BaseIndent, "release: ", erlang:atom_to_list(Name), "-", Vsn, "\n",
+    [BaseIndent, "release: ", rcl_util:to_string(Name), "-", Vsn, "\n",
      rcl_util:indent(Indent + 1), " erts-", ErtsVsn,
      ", realized = ",  erlang:atom_to_list(Realized), "\n",
      BaseIndent, "goals: \n",
@@ -189,7 +196,7 @@ format_error({topo_error, E}) ->
     rcl_topo:format_error(E);
 format_error({failed_to_parse, Con}) ->
     io_lib:format("Failed to parse constraint ~p", [Con]);
-format_error({invalid_constraint, Con}) ->
+format_error({invalid_constraint, _, Con}) ->
     io_lib:format("Invalid constraint specified ~p", [Con]);
 format_error({not_realized, Name, Vsn}) ->
     io_lib:format("Unable to produce metadata release: ~p-~s has not been realized",
@@ -209,10 +216,10 @@ realize_erts(Rel) ->
 process_specs(Rel=#release_t{annotations=Annots,
                              goals=Goals}, World) ->
     ActiveApps = lists:flatten([rcl_app_info:active_deps(El) || El <- World] ++
-                                   [case get_app_name(Goal) of
-                                        {error, _} -> [];
-                                        G -> G
-                                    end || Goal <- Goals]),
+                                  [case get_app_name(Goal) of
+                                       {error, _} -> [];
+                                       G -> G
+                                   end || Goal <- Goals]),
     LibraryApps = lists:flatten([rcl_app_info:library_deps(El) || El <- World]),
     Specs = [create_app_spec(Annots, App, ActiveApps, LibraryApps) || App <- World],
     {ok, Rel#release_t{annotations=Annots,
@@ -308,7 +315,7 @@ parse_goal0(Constraint0, {ok, Release}) ->
 parse_goal0(_, E = {error, _}) ->
     E;
 parse_goal0(Constraint, _) ->
-    ?RCL_ERROR({invalid_constraint, Constraint}).
+    ?RCL_ERROR({invalid_constraint, 1, Constraint}).
 
 parse_goal1(Release = #release_t{annotations=Annots,  goals=Goals},
             Constraint, NewAnnots) ->
@@ -331,25 +338,52 @@ parse_constraint(Constraint0)
         {ok, Constraint1} ->
             {ok, Constraint1}
     end;
-parse_constraint(Constraint)
-  when erlang:is_tuple(Constraint);
-       erlang:is_atom(Constraint) ->
-    case rcl_depsolver:is_valid_constraint(Constraint) of
+parse_constraint(Constraint0)
+  when erlang:is_tuple(Constraint0);
+       erlang:is_atom(Constraint0) ->
+    Constraint1 = parse_version(Constraint0),
+    case rcl_depsolver:is_valid_constraint(Constraint1) of
         false ->
-            ?RCL_ERROR({invalid_constraint, Constraint});
+            ?RCL_ERROR({invalid_constraint, 2, Constraint0});
         true ->
-            {ok, Constraint}
+            {ok, Constraint1}
     end;
 parse_constraint(Constraint) ->
-    ?RCL_ERROR({invalid_constraint, Constraint}).
+    ?RCL_ERROR({invalid_constraint, 3, Constraint}).
 
--spec get_app_name(rcl_depsolver:constraint()) ->
+-spec get_app_name(rcl_depsolver:raw_constraint()) ->
                           AppName::atom() | relcool:error().
 get_app_name(AppName) when erlang:is_atom(AppName) ->
     AppName;
+get_app_name({AppName, _}) when erlang:is_atom(AppName) ->
+    AppName;
 get_app_name({AppName, _, _}) when erlang:is_atom(AppName) ->
     AppName;
 get_app_name({AppName, _, _, _}) when erlang:is_atom(AppName) ->
     AppName;
 get_app_name(V) ->
-    ?RCL_ERROR({invalid_constraint, V}).
+    ?RCL_ERROR({invalid_constraint, 4, V}).
+
+-spec parse_version(rcl_depsolver:raw_constraint()) ->
+                           rcl_depsolver:constraint().
+parse_version({AppName, Version})
+  when erlang:is_binary(Version);
+       erlang:is_list(Version) ->
+    {AppName, rcl_depsolver:parse_version(Version)};
+parse_version({AppName, Version, Constraint})
+  when erlang:is_binary(Version);
+       erlang:is_list(Version) ->
+    {AppName, rcl_depsolver:parse_version(Version), Constraint};
+parse_version({AppName, Version, Constraint0, Constraint1})
+  when erlang:is_binary(Version);
+       erlang:is_list(Version) ->
+    {AppName, rcl_depsolver:parse_version(Version), Constraint1, Constraint0};
+parse_version(Constraint) ->
+    Constraint.
+
+to_atom(RelName)
+  when erlang:is_list(RelName) ->
+    erlang:list_to_atom(RelName);
+to_atom(Else)
+  when erlang:is_atom(Else) ->
+    Else.
diff --git a/src/rcl_state.erl b/src/rcl_state.erl
index 7397e6f..6fd5655 100644
--- a/src/rcl_state.erl
+++ b/src/rcl_state.erl
@@ -1,4 +1,4 @@
-%%% -*- mode: Erlang; fill-column: 80; comment-column: 75; -*-
+%% -*- erlang-indent-level: 4; indent-tabs-mode: nil; fill-column: 80 -*-
 %%% Copyright 2012 Erlware, LLC. All Rights Reserved.
 %%%
 %%% This file is provided to you under the Apache License,
@@ -30,11 +30,14 @@
          overrides/1,
          overrides/2,
          goals/1,
-         config_files/1,
+         config_file/1,
+         config_file/2,
          providers/1,
          providers/2,
          sys_config/1,
          sys_config/2,
+         root_dir/1,
+         root_dir/2,
          add_release/2,
          get_release/3,
          update_release/2,
@@ -57,10 +60,12 @@
               cmd_args/0]).
 
 -record(state_t, {log :: rcl_log:t(),
+                  root_dir :: file:name(),
                   caller :: caller(),
+                  action :: atom(),
                   output_dir :: file:name(),
                   lib_dirs=[] :: [file:name()],
-                  config_files=[] :: [file:filename()],
+                  config_file=[] :: file:filename() | undefined,
                   goals=[] :: [rcl_depsolver:constraint()],
                   providers = [] :: [rcl_provider:t()],
                   available_apps = [] :: [rcl_app_info:t()],
@@ -88,21 +93,28 @@
 %% API
 %%============================================================================
 %% @doc Create a new 'log level' for the system
--spec new(proplists:proplist(), [file:filename()] | file:filename()) -> t().
-new(PropList, Targets) when erlang:is_list(PropList) ->
+-spec new(proplists:proplist(), atom()) -> t().
+new(PropList, Target)
+  when erlang:is_list(PropList),
+     erlang:is_atom(Target) ->
+    {ok, Root} = file:get_cwd(),
     State0 =
         #state_t{log = proplists:get_value(log, PropList, rcl_log:new(error)),
-                 output_dir=filename:absname(proplists:get_value(output_dir, PropList, "")),
-                 lib_dirs=get_lib_dirs(proplists:get_value(lib_dirs, PropList, [])),
-                 config_files=process_config_files(Targets),
+                 output_dir=proplists:get_value(output_dir, PropList, ""),
+                 lib_dirs=proplists:get_value(lib_dirs, PropList, ""),
+                 config_file=proplists:get_value(config, PropList, undefined),
+                 action = Target,
                  goals=proplists:get_value(goals, PropList, []),
                  providers = [],
                  releases=ec_dictionary:new(ec_dict),
                  config_values=ec_dictionary:new(ec_dict),
                  overrides = proplists:get_value(overrides, PropList, []),
+                 root_dir = proplists:get_value(root_dir, PropList, Root),
                  default_release={proplists:get_value(relname, PropList, undefined),
                                   proplists:get_value(relvsn, PropList, undefined)}},
-    create_logic_providers(State0).
+    rcl_state:put(create_logic_providers(State0),
+                  disable_default_libs,
+                  proplists:get_value(disable_default_libs, PropList, false)).
 
 %% @doc the application overrides for the system
 -spec overrides(t()) -> [{AppName::atom(), Directory::file:filename()}].
@@ -127,14 +139,18 @@ output_dir(#state_t{output_dir=OutDir}) ->
 lib_dirs(#state_t{lib_dirs=LibDir}) ->
     LibDir.
 
--spec goals(t()) -> [rcl_depsolver:constraints()].
+-spec goals(t()) -> [rcl_depsolver:constraint()].
 goals(#state_t{goals=TS}) ->
     TS.
 
--spec config_files(t()) -> [file:filename()].
-config_files(#state_t{config_files=ConfigFiles}) ->
+-spec config_file(t()) -> file:filename() | undefined.
+config_file(#state_t{config_file=ConfigFiles}) ->
     ConfigFiles.
 
+-spec config_file(t(), file:filename() | undefined) -> t().
+config_file(State, ConfigFiles) ->
+    State#state_t{config_file=ConfigFiles}.
+
 -spec providers(t()) -> [rcl_provider:t()].
 providers(#state_t{providers=Providers}) ->
     Providers.
@@ -147,6 +163,14 @@ sys_config(#state_t{sys_config=SysConfig}) ->
 sys_config(State, SysConfig) ->
     State#state_t{sys_config=SysConfig}.
 
+-spec root_dir(t()) -> file:filename() | undefined.
+root_dir(#state_t{root_dir=RootDir}) ->
+    RootDir.
+
+-spec root_dir(t(), file:filename()) -> t().
+root_dir(State, RootDir) ->
+    State#state_t{root_dir=RootDir}.
+
 -spec providers(t(), [rcl_provider:t()]) -> t().
 providers(M, NewProviders) ->
     M#state_t{providers=NewProviders}.
@@ -225,15 +249,14 @@ format(Mod) ->
 -spec format(t(), non_neg_integer()) -> iolist().
 format(#state_t{log=LogState, output_dir=OutDir, lib_dirs=LibDirs,
                 caller=Caller, config_values=Values0,
-                goals=Goals, config_files=ConfigFiles,
+                goals=Goals, config_file=ConfigFile,
                 providers=Providers},
        Indent) ->
     Values1 = ec_dictionary:to_list(Values0),
     [rcl_util:indent(Indent),
      <<"state(">>, erlang:atom_to_list(Caller), <<"):\n">>,
      rcl_util:indent(Indent + 1), <<"log: ">>, rcl_log:format(LogState), <<",\n">>,
-     rcl_util:indent(Indent + 1), "config files: \n",
-     [[rcl_util:indent(Indent + 2), ConfigFile, ",\n"] || ConfigFile <- ConfigFiles],
+     rcl_util:indent(Indent + 1), "config file: ", rcl_util:optional_to_string(ConfigFile), "\n",
      rcl_util:indent(Indent + 1), "goals: \n",
      [[rcl_util:indent(Indent + 2), rcl_depsolver:format_constraint(Goal), ",\n"] || Goal <- Goals],
      rcl_util:indent(Indent + 1), "output_dir: ", OutDir, "\n",
@@ -247,36 +270,16 @@ format(#state_t{log=LogState, output_dir=OutDir, lib_dirs=LibDirs,
 %%%===================================================================
 %%% Internal Functions
 %%%===================================================================
--spec get_lib_dirs([file:name()]) -> [file:name()].
-get_lib_dirs(CmdDirs) ->
-    case os:getenv("ERL_LIBS") of
-        false ->
-            CmdDirs;
-        EnvString ->
-            [Lib || Lib <- re:split(EnvString, ":|;"),
-                     filelib:is_dir(Lib)] ++ CmdDirs
-    end.
 
 -spec create_logic_providers(t()) -> t().
 create_logic_providers(State0) ->
     {ConfigProvider, {ok, State1}} = rcl_provider:new(rcl_prv_config, State0),
     {DiscoveryProvider, {ok, State2}} = rcl_provider:new(rcl_prv_discover, State1),
     {ReleaseProvider, {ok, State3}} = rcl_provider:new(rcl_prv_release, State2),
-    {AssemblerProvider, {ok, State4}} = rcl_provider:new(rcl_prv_assembler, State3),
-    State4#state_t{providers=[ConfigProvider, DiscoveryProvider,
-                              ReleaseProvider, AssemblerProvider]}.
-
-
-%% @doc config files can come in as either a single file name or as a list of
-%% files. We what to support both where possible.
-process_config_files(File = [Char | _])
-  when erlang:is_integer(Char) ->
-    [File];
-process_config_files(Files = [File | _])
-  when erlang:is_list(File) ->
-    Files;
-process_config_files([]) ->
-    [].
+    {OverlayProvider, {ok, State4}} = rcl_provider:new(rcl_prv_overlay, State3),
+    {AssemblerProvider, {ok, State5}} = rcl_provider:new(rcl_prv_assembler, State4),
+    State5#state_t{providers=[ConfigProvider, DiscoveryProvider,
+                              ReleaseProvider, OverlayProvider, AssemblerProvider]}.
 
 %%%===================================================================
 %%% Test Functions
@@ -287,7 +290,7 @@ process_config_files([]) ->
 
 new_test() ->
     LogState = rcl_log:new(error),
-    RCLState = new([{log, LogState}], []),
+    RCLState = new([{log, LogState}], release),
     ?assertMatch(LogState, log(RCLState)).
 
 -endif.
diff --git a/src/rcl_topo.erl b/src/rcl_topo.erl
index ec67b56..462b7c5 100644
--- a/src/rcl_topo.erl
+++ b/src/rcl_topo.erl
@@ -1,4 +1,19 @@
-%% -*- mode: Erlang; fill-column: 80; comment-column: 75; -*-
+%% -*- erlang-indent-level: 4; indent-tabs-mode: nil; fill-column: 80 -*-
+%%% Copyright 2012 Erlware, LLC. All Rights Reserved.
+%%%
+%%% This file is provided to you under the Apache License,
+%%% Version 2.0 (the "License"); you may not use this file
+%%% except in compliance with the License.  You may obtain
+%%% a copy of the License at
+%%%
+%%%   http://www.apache.org/licenses/LICENSE-2.0
+%%%
+%%% Unless required by applicable law or agreed to in writing,
+%%% software distributed under the License is distributed on an
+%%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+%%% KIND, either express or implied.  See the License for the
+%%% specific language governing permissions and limitations
+%%% under the License.
 %%%-------------------------------------------------------------------
 %%% @author Joe Armstrong
 %%% @author Eric Merritt
diff --git a/src/rcl_util.erl b/src/rcl_util.erl
index f6427ae..61e1392 100644
--- a/src/rcl_util.erl
+++ b/src/rcl_util.erl
@@ -1,4 +1,4 @@
-%% -*- mode: Erlang; fill-column: 80; comment-column: 75; -*-
+%% -*- erlang-indent-level: 4; indent-tabs-mode: nil; fill-column: 80 -*-
 %%% Copyright 2012 Erlware, LLC. All Rights Reserved.
 %%%
 %%% This file is provided to you under the Apache License,
@@ -23,7 +23,11 @@
 
 -export([mkdir_p/1,
          to_binary/1,
-         indent/1]).
+         to_string/1,
+         is_error/1,
+         error_reason/1,
+         indent/1,
+         optional_to_string/1]).
 
 -define(ONE_LEVEL_INDENT, "    ").
 %%============================================================================
@@ -54,7 +58,27 @@ to_binary(String) when erlang:is_list(String) ->
     erlang:iolist_to_binary(String);
 to_binary(Bin) when erlang:is_binary(Bin) ->
     Bin.
+to_string(Atom) when erlang:is_atom(Atom) ->
+    erlang:atom_to_list(Atom);
+to_string(Else) when erlang:is_list(Else) ->
+    Else.
 
+%% @doc get the reason for a particular relcool error
+-spec error_reason(relcool:error()) -> any().
+error_reason({error, {_, Reason}}) ->
+    Reason.
+%% @doc check to see if the value is a relcool error
+-spec is_error(relcool:error() | any()) -> boolean().
+is_error({error, _}) ->
+    true;
+is_error(_) ->
+    false.
+
+%% @doc convert optional argument to empty string if undefined
+optional_to_string(undefined) ->
+    "";
+optional_to_string(Value) when is_list(Value) ->
+    Value.
 
 %%%===================================================================
 %%% Test Functions
diff --git a/src/relcool.erl b/src/relcool.erl
index 0d75c62..c8c0cde 100644
--- a/src/relcool.erl
+++ b/src/relcool.erl
@@ -1,4 +1,4 @@
-%%% -*- mode: Erlang; fill-column: 80; comment-column: 75; -*-
+%% -*- erlang-indent-level: 4; indent-tabs-mode: nil; fill-column: 80 -*-
 %%% Copyright 2012 Erlware, LLC. All Rights Reserved.
 %%%
 %%% This file is provided to you under the Apache License,
@@ -23,6 +23,7 @@
 -export([main/1,
          do/7,
          do/8,
+         do/9,
          format_error/1,
          opt_spec_list/0]).
 
@@ -35,6 +36,7 @@
 %%============================================================================
 
 -type error() :: {error, {Module::module(), Reason::term()}}.
+-type goal() :: string() | binary() | rcl_depsolver:constraint().
 
 %%============================================================================
 %% API
@@ -42,12 +44,20 @@
 -spec main([string()]) -> ok | error() | {ok, rcl_state:t()}.
 main(Args) ->
     OptSpecList = opt_spec_list(),
-    case rcl_cmd_args:args2state(getopt:parse(OptSpecList, Args)) of
-        {ok, {State, _Target}} ->
-            run_relcool_process(rcl_state:caller(State, command_line));
-        Error={error, _} ->
-            report_error(rcl_state:caller(rcl_state:new([], []),
-                                          command_line), Error)
+    Result =
+        case rcl_cmd_args:args2state(getopt:parse(OptSpecList, Args)) of
+            {ok, State} ->
+                run_relcool_process(rcl_state:caller(State, command_line));
+            Error={error, _} ->
+                Error
+        end,
+    case Result of
+        {error, _} ->
+            report_error(rcl_state:caller(rcl_state:new([], undefined),
+                                          command_line),
+                         Result);
+        _ ->
+            Result
     end.
 
 %% @doc provides an API to run the Relcool process from erlang applications
@@ -59,11 +69,32 @@ main(Args) ->
 %% @param LibDirs - The library dirs that should be used for the system
 %% @param OutputDir - The directory where the release should be built to
 %% @param Configs - The list of config files for the system
-do(RelName, RelVsn, Goals, LibDirs, LogLevel, OutputDir, Configs) ->
-    do(RelName, RelVsn, Goals, LibDirs, LogLevel, OutputDir, [], Configs).
+-spec do(atom(), string(), [goal()], [file:name()], rcl_log:log_level(),
+         [file:name()], file:name()) ->
+                  ok | error() | {ok, rcl_state:t()}.
+do(RelName, RelVsn, Goals, LibDirs, LogLevel, OutputDir, Config) ->
+    {ok, Cwd} = file:get_cwd(),
+    do(Cwd, RelName, RelVsn, Goals, LibDirs, LogLevel, OutputDir, [], Config).
+
+%% @doc provides an API to run the Relcool process from erlang applications
+%%
+%% @param RootDir - The root directory for the project
+%% @param RelName - The release name to build (maybe `undefined`)
+%% @param RelVsn - The release version to build (maybe `undefined`)
+%% @param Goals - The release goals for the system in depsolver or Relcool goal
+%% format
+%% @param LibDirs - The library dirs that should be used for the system
+%% @param OutputDir - The directory where the release should be built to
+%% @param Configs - The list of config files for the system
+-spec do(file:name(), atom(), string(), [goal()], [file:name()],
+           rcl_log:log_level(), [file:name()], file:name()) ->
+                  ok | error() | {ok, rcl_state:t()}.
+do(RootDir, RelName, RelVsn, Goals, LibDirs, LogLevel, OutputDir, Configs) ->
+    do(RootDir, RelName, RelVsn, Goals, LibDirs, LogLevel, OutputDir, [], Configs).
 
 %% @doc provides an API to run the Relcool process from erlang applications
 %%
+%% @param RootDir - The root directory for the system
 %% @param RelName - The release name to build (maybe `undefined`)
 %% @param RelVsn - The release version to build (maybe `undefined`)
 %% @param Goals - The release goals for the system in depsolver or Relcool goal
@@ -72,29 +103,41 @@ do(RelName, RelVsn, Goals, LibDirs, LogLevel, OutputDir, Configs) ->
 %% @param OutputDir - The directory where the release should be built to
 %% @param Overrides - A list of overrides for the system
 %% @param Configs - The list of config files for the system
-do(RelName, RelVsn, Goals, LibDirs, LogLevel, OutputDir, Overrides, Configs) ->
+-spec do(file:name(), atom(), string(), [goal()], [file:name()],
+           rcl_log:log_level(), [file:name()], [{atom(), file:name()}], file:name()) ->
+                  ok | error() | {ok, rcl_state:t()}.
+do(RootDir, RelName, RelVsn, Goals, LibDirs, LogLevel, OutputDir, Overrides, Config) ->
     State = rcl_state:new([{relname, RelName},
                            {relvsn, RelVsn},
                            {goals, Goals},
                            {overrides, Overrides},
                            {output_dir, OutputDir},
                            {lib_dirs, LibDirs},
-                           {log, rcl_log:new(LogLevel)}],
-                          Configs),
+                           {root_dir, RootDir},
+                           {log, rcl_log:new(LogLevel)},
+                           {config, Config}],
+                          release),
     run_relcool_process(rcl_state:caller(State, api)).
 
 
 -spec opt_spec_list() -> [getopt:option_spec()].
 opt_spec_list() ->
-    [
-     {relname,  $n, "relname",  string,  "Specify the name for the release that will be generated"},
+    [{relname,  $n, "relname",  string,
+      "Specify the name for the release that will be generated"},
      {relvsn, $v, "relvsn", string, "Specify the version for the release"},
-     {goals, $g, "goal", string, "Specify a target constraint on the system. These are "
-      "usually the OTP"},
-     {output_dir, $o, "output-dir", string, "The output directory for the release. This is `./` by default."},
-     {lib_dir, $l, "lib-dir", string, "Additional dirs that should be searched for OTP Apps"},
-     {log_level, $V, "verbose", {integer, 2}, "Verbosity level, maybe between 0 and 2"}
-    ].
+     {goals, $g, "goal", string,
+      "Specify a target constraint on the system. These are usually the OTP"},
+     {output_dir, $o, "output-dir", string,
+      "The output directory for the release. This is `./` by default."},
+     {lib_dir, $l, "lib-dir", string,
+      "Additional dirs that should be searched for OTP Apps"},
+     {disable_default_libs, undefined, "disable-default-libs",
+      {boolean, false},
+      "Disable the default system added lib dirs (means you must add them all manually"},
+     {log_level, $V, "verbose", {integer, 1},
+      "Verbosity level, maybe between 0 and 2"},
+     {config, $c, "config", {string, ""}, "The path to a config file"},
+     {root_dir, $r, "root", string, "The project root directory"}].
 
 -spec format_error(Reason::term()) -> iolist().
 format_error({invalid_return_value, Provider, Value}) ->
@@ -103,7 +146,6 @@ format_error({invalid_return_value, Provider, Value}) ->
 format_error({error, {Module, Reason}}) ->
     io_lib:format("~s~n", [Module:format_error(Reason)]).
 
-
 %%============================================================================
 %% internal api
 %%============================================================================
@@ -126,6 +168,8 @@ run_providers(State0) ->
         Err = {error, _} ->
             Err;
         {ok, State1} ->
+            RootDir = rcl_state:root_dir(State1),
+            ok = file:set_cwd(RootDir),
             Providers = rcl_state:providers(State1),
             Result = run_providers(ConfigProvider, Providers, State1),
             handle_output(State1, rcl_state:caller(State1), Result)
@@ -158,9 +202,12 @@ run_provider(Provider, {ok, State0}) ->
                   [rcl_provider:impl(Provider)]),
     case rcl_provider:do(Provider, State0) of
         {ok, State1} ->
+            rcl_log:debug(rcl_state:log(State0), "Provider successfully run: ~p~n",
+                          [rcl_provider:impl(Provider)]),
             {ok, State1};
         E={error, _} ->
-
+            rcl_log:debug(rcl_state:log(State0), "Provider (~p) failed with: ~p~n",
+                          [rcl_provider:impl(Provider), E]),
             E
     end.
 
@@ -168,7 +215,6 @@ run_provider(Provider, {ok, State0}) ->
 usage() ->
     getopt:usage(opt_spec_list(), "relcool", "[*release-specification-file*]").
 
-
 -spec report_error(rcl_state:t(), error()) -> none() | error().
 report_error(State, Error) ->
     io:format(format_error(Error)),