support overlay file inclusion

allow overlay inclusion of other files, similarly
to what OTP already does in sys.config files

3 files changed, 30 insertions, 2 deletions

diff --git a/src/rlx_prv_overlay.erl b/src/rlx_prv_overlay.erl
index ab0f74e..cdce915 100644
--- a/src/rlx_prv_overlay.erl
+++ b/src/rlx_prv_overlay.erl
@@ -161,6 +161,21 @@ read_overlay_vars(State, OverlayVars, FileNames) ->
             Error
     end.
 
+-spec check_overlay_inclusion(rlx_state:t(), string(), proplists:proplist()) ->
+                              proplists:proplist().
+check_overlay_inclusion(State, RelativeRoot, Terms) ->
+    check_overlay_inclusion(State, RelativeRoot, Terms, []).
+
+-spec check_overlay_inclusion(rlx_state:t(), string(), proplists:proplist(), proplists:proplist()) ->
+                              proplists:proplist().
+check_overlay_inclusion(State, RelativeRoot, [File|T], Terms) when is_list(File) ->
+    IncludedTerms = merge_overlay_vars(State, [filename:join(RelativeRoot, File)]),
+    check_overlay_inclusion(State, RelativeRoot, T, Terms ++ IncludedTerms);
+check_overlay_inclusion(State, RelativeRoot, [Tuple|T], Terms) ->
+    check_overlay_inclusion(State, RelativeRoot, T, Terms ++ [Tuple]);
+check_overlay_inclusion(_State, _RelativeRoot, [], Terms) ->
+    Terms.
+
 -spec merge_overlay_vars(rlx_state:t(), [file:name()]) ->
                                 proplists:proplist().
 merge_overlay_vars(State, FileNames) ->
@@ -169,7 +184,11 @@ merge_overlay_vars(State, FileNames) ->
                         RelativePath = filename:join(RelativeRoot, erlang:iolist_to_binary(FileName)),
                         case file:consult(RelativePath) of
                             {ok, Terms} ->
-                                lists:ukeymerge(1, lists:ukeysort(1, Terms), Acc);
+                                % the location of the included overlay files will be relative
+                                %% to the current one being read
+                                OverlayRelativeRoot = filename:dirname(FileName),
+                                NewTerms = check_overlay_inclusion(State, OverlayRelativeRoot, Terms),
+                                lists:ukeymerge(1, lists:ukeysort(1, NewTerms), Acc);
                             {error, Reason} ->
                                 ec_cmd_log:warn(rlx_state:log(State),
                                                 format_error({unable_to_read_varsfile, FileName, Reason})),
diff --git a/test/rlx_release_SUITE.erl b/test/rlx_release_SUITE.erl
index eeab491..766eb40 100644
--- a/test/rlx_release_SUITE.erl
+++ b/test/rlx_release_SUITE.erl
@@ -471,6 +471,7 @@ overlay_release(Config) ->
     ConfigFile = filename:join([LibDir1, "relx.config"]),
     OverlayVars1 = filename:join([LibDir1, "vars1.config"]),
     OverlayVars2 = filename:join([LibDir1, "vars2.config"]),
+    OverlayVars3 = filename:join([LibDir1, "vars3.config"]),
     Template = filename:join([LibDir1, "test_template"]),
     TestDir = "first_test_dir",
     TestFile = "test_file",
@@ -502,7 +503,12 @@ overlay_release(Config) ->
 
     VarsFile2 = filename:join([LibDir1, "vars2.config"]),
     rlx_test_utils:write_config(VarsFile2, [{google, "yahoo"},
-                             {yahoo2, [{foo, "foo"}]}]),
+                             {yahoo2, [{foo, "foo"}]},
+                             OverlayVars3]),
+
+    VarsFile3 = filename:join([LibDir1, "vars3.config"]),
+    rlx_test_utils:write_config(VarsFile3, [{google, "yahoo"},
+                             {yahoo4, [{foo, "{{yahoo}}/{{yahoo2.foo}}4"}]}]),
 
     ok = rlx_util:mkdir_p(TestDirFull),
     ok = file:write_file(TestFileFull, rlx_test_utils:test_template_contents()),
@@ -604,6 +610,8 @@ overlay_release(Config) ->
                  proplists:get_value(foo_dir, TemplateData)),
     ?assertEqual("yahoo/foo",
                  proplists:get_value(yahoo3, TemplateData)),
+    ?assertEqual("yahoo/foo4",
+                 proplists:get_value(yahoo4, TemplateData)),
     ?assertEqual("yahoo",
                  proplists:get_value(google, TemplateData)).
 
diff --git a/test/rlx_test_utils.erl b/test/rlx_test_utils.erl
index 0428966..644c49f 100644
--- a/test/rlx_test_utils.erl
+++ b/test/rlx_test_utils.erl
@@ -94,4 +94,5 @@ test_template_contents() ->
         "{yahoo2_foo, \"{{yahoo2.foo}}\"}.\n"
         "{foo_dir, \"{{foo_dir}}\"}.\n"
         "{yahoo3, \"{{yahoo3.bar}}\"}.\n"
+        "{yahoo4, \"{{yahoo4.foo}}\"}.\n"
         "{google, \"{{google}}\"}.\n".