From 84adefa331c4159d432d22840663c38f155cd4c1 Mon Sep 17 00:00:00 2001 From: Erlang/OTP Date: Fri, 20 Nov 2009 14:54:40 +0000 Subject: The R13B03 release. --- system/doc/system_principles/create_target.xml | 502 +++++++++++++++++++++++++ 1 file changed, 502 insertions(+) create mode 100644 system/doc/system_principles/create_target.xml (limited to 'system/doc/system_principles/create_target.xml') diff --git a/system/doc/system_principles/create_target.xml b/system/doc/system_principles/create_target.xml new file mode 100644 index 0000000000..9899b6e266 --- /dev/null +++ b/system/doc/system_principles/create_target.xml @@ -0,0 +1,502 @@ + + + + +
+ + 20022009 + Ericsson AB. All Rights Reserved. + + + The contents of this file are subject to the Erlang Public License, + Version 1.1, (the "License"); you may not use this file except in + compliance with the License. You should have received a copy of the + Erlang Public License along with this software. If not, it can be + retrieved online at http://www.erlang.org/. + + Software distributed under the License is distributed on an "AS IS" + basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See + the License for the specific language governing rights and limitations + under the License. + + + + Creating a First Target System + Peter Högfeldt + + + + + 2002-09-17 + A + create_target.xml +
+ +
+ Introduction +

When creating a system using Erlang/OTP, the most simple way is + to install Erlang/OTP somewhere, install the application specific + code somewhere else, and then start the Erlang runtime system, + making sure the code path includes the application specific code.

+

Often it is not desirable to use an Erlang/OTP system as is. A + developer may create new Erlang/OTP compliant applications for a + particular purpose, and several original Erlang/OTP applications + may be irrelevant for the purpose in question. Thus, there is a + need to be able to create a new system based on a given + Erlang/OTP system, where dispensable applications are removed, + and a set of new applications that are included in the new + system. Documentation and source code is irrelevant and is + therefore not included in the new system.

+

This chapter is about creating such a system, which we call a + target system.

+

In the following sections we consider creating target systems with + different requirements of functionality:

+ + a basic target system that can be started by + calling the ordinary erl script, + a simple target system where also code + replacement in run-time can be performed, and + an embedded target system where there is also + support for logging output from the system to file for later + inspection, and where the system can be started automatically + at boot time. + +

We only consider the case when Erlang/OTP is running on a UNIX + system.

+

There is an example Erlang module target_system.erl that + contains functions for creating and installing a target system. + That module is used in the examples below. The source code of + the module is listed at the end of this chapter.

+
+ +
+ Creating a Target System +

It is assumed that you have a working Erlang/OTP system structured + according to the OTP Design Principles.

+

Step 1. First create a .rel file (see + rel(4)) that specifies the erts version + and lists all applications that should be included in the new + basic target system. An example is the following + mysystem.rel file:

+ +%% mysystem.rel +{release, + {"MYSYSTEM", "FIRST"}, + {erts, "5.1"}, + [{kernel, "2.7"}, + {stdlib, "1.10"}, + {sasl, "1.9.3"}, + {pea, "1.0"}]}. +

The listed applications are not only original Erlang/OTP + applications but possibly also new applications that you have + written yourself (here examplified by the application + pea).

+

Step 2. From the directory where the mysystem.rel + file reside, start the Erlang/OTP system:

+ 
+os> erl -pa /home/user/target_system/myapps/pea-1.0/ebin
+

where also the path to the pea-1.0 ebin directory is + provided.

+

Step 3. Now create the target system:

+ 
+1> target_system:create("mysystem").
+

The target_system:create/1 function does the following:

+ + Reads the mysystem.rel file, and creates a new file + plain.rel which is identical to former, except that it + only lists the kernel and stdlib applications. + From the mysystem.rel and plain.rel files + creates the files mysystem.script, + mysystem.boot, plain.script, and + plain.boot through a call to + systools:make_script/2. + +

Creates the file mysystem.tar.gz by a call to + systools:make_tar/2. That file has the following + contents:

+ +erts-5.1/bin/ +releases/FIRST/start.boot +releases/mysystem.rel +lib/kernel-2.7/ +lib/stdlib-1.10/ +lib/sasl-1.9.3/ +lib/pea-1.0/ +

The file releases/FIRST/start.boot is a copy of our + mysystem.boot, and a copy of the original + mysystem.rel has been put in the releases + directory.

+ + Creates the temporary directory tmp and extracts the tar file + mysystem.tar.gz into that directory. + Deletes the erl and start files from + tmp/erts-5.1/bin. XXX Why. + Creates the directory tmp/bin. + Copies the previously creates file plain.boot to + tmp/bin/start.boot. + Copies the files epmd, run_erl, and + to_erl from the directory tmp/erts-5.1/bin to + the directory tmp/bin. + Creates the file tmp/releases/start_erl.data with the + contents "5.1 FIRST". + + Recreates the file mysystem.tar.gz from the directories + in the directory tmp, and removes tmp. + +
+ +
+ Installing a Target System +

Step 4. Install the created target system in a + suitable directory.

+ 
+2> target_system:install("mysystem", "/usr/local/erl-target").
+

The function target_system:install/2 does the following: +

+ + Extracts the tar file mysystem.tar.gz into the target + directory /usr/local/erl-target. + In the target directory reads the file releases/start_erl.data + in order to find the Erlang runtime system version ("5.1"). + Substitutes %FINAL_ROOTDIR% and %EMU% for + /usr/local/erl-target and beam, respectively, in + the files erl.src, start.src, and + start_erl.src of the target erts-5.1/bin + directory, and puts the resulting files erl, + start, and run_erl in the target bin + directory. + Finally the target releases/RELEASES file is created + from data in the releases/mysystem.rel file. + +
+ +
+ Starting a Target System +

Now we have a target system that can be started in various ways.

+

We start it as a basic target system by invoking

+ 
+os> /usr/local/erl-target/bin/erl
+

where only the kernel and stdlib applications are + started, i.e. the system is started as an ordinary development + system. There are only two files needed for all this to work: + bin/erl file (obtained from erts-5.1/bin/erl.src) + and the bin/start.boot file (a copy of plain.boot).

+

We can also start a distributed system (requires bin/epmd).

+

To start all applications specified in the original + mysystem.rel file, use the -boot flag as follows:

+ 
+os> /usr/local/erl-target/bin/erl -boot /usr/local/erl-target/releases/FIRST/start
+

We start a simple target system as above. The only difference + is that also the file releases/RELEASES is present for + code replacement in run-time to work.

+

To start an embedded target system the shell script + bin/start is used. That shell script calls + bin/run_erl, which in turn calls bin/start_erl + (roughly, start_erl is an embedded variant of + erl).

+

The shell script start is only an example. You should + edit it to suite your needs. Typically it is executed when the + UNIX system boots.

+

run_erl is a wrapper that provides logging of output from + the run-time system to file. It also provides a simple mechanism + for attaching to the Erlang shell (to_erl).

+

start_erl requires the root directory + ("/usr/local/erl-target"), the releases directory + ("/usr/local/erl-target/releases"), and the location of + the start_erl.data file. It reads the run-time system + version ("5.1") and release version ("FIRST") from + the start_erl.data file, starts the run-time system of the + version found, and provides -boot flag specifying the boot + file of the release version found + ("releases/FIRST/start.boot").

+

start_erl also assumes that there is sys.config in + release version directory ("releases/FIRST/sys.config). That + is the topic of the next section (see below).

+

The start_erl shell script should normally not be + altered by the user.

+
+ +
+ System Configuration Parameters +

As was pointed out above start_erl requires a + sys.config in the release version directory + ("releases/FIRST/sys.config"). If there is no such a + file, the system start will fail. Hence such a file has to + added as well.

+

+

If you have system configuration data that are neither file + location dependent nor site dependent, it may be convenient to + create the sys.config early, so that it becomes a part of + the target system tar file created by + target_system:create/1. In fact, if you create, in the + current directory, not only the mysystem.rel file, but + also a sys.config file, that latter file will be tacitly + put in the apropriate directory.

+
+ +
+ Differences from the Install Script +

The above install/2 procedure differs somewhat from that + of the ordinary Install shell script. In fact, create/1 + makes the release package as complete as possible, and leave to the + install/2 procedure to finish by only considering location + dependent files.

+
+ +
+ Listing of target_system.erl + + RelFile = RelFileName ++ ".rel", + io:fwrite("Reading file: \\"~s\\" ...~n", [RelFile]), + {ok, [RelSpec]} = file:consult(RelFile), + io:fwrite("Creating file: \\"~s\\" from \\"~s\\" ...~n", + ["plain.rel", RelFile]), + {release, + {RelName, RelVsn}, + {erts, ErtsVsn}, + AppVsns} = RelSpec, + PlainRelSpec = {release, + {RelName, RelVsn}, + {erts, ErtsVsn}, + lists:filter(fun({kernel, _}) -> + true; + ({stdlib, _}) -> + true; + (_) -> + false + end, AppVsns) + }, + {ok, Fd} = file:open("plain.rel", [write]), + io:fwrite(Fd, "~p.~n", [PlainRelSpec]), + file:close(Fd), + + io:fwrite("Making \\"plain.script\\" and \\"plain.boot\\" files ...~n"), + make_script("plain"), + + io:fwrite("Making \\"~s.script\\" and \\"~s.boot\\" files ...~n", + [RelFileName, RelFileName]), + make_script(RelFileName), + + TarFileName = io_lib:fwrite("~s.tar.gz", [RelFileName]), + io:fwrite("Creating tar file \\"~s\\" ...~n", [TarFileName]), + make_tar(RelFileName), + + io:fwrite("Creating directory \\"tmp\\" ...~n"), + file:make_dir("tmp"), + + io:fwrite("Extracting \\"~s\\" into directory \\"tmp\\" ...~n", [TarFileName]), + extract_tar(TarFileName, "tmp"), + + TmpBinDir = filename:join(["tmp", "bin"]), + ErtsBinDir = filename:join(["tmp", "erts-" ++ ErtsVsn, "bin"]), + io:fwrite("Deleting \\"erl\\" and \\"start\\" in directory \\"~s\\" ...~n", + [ErtsBinDir]), + file:delete(filename:join([ErtsBinDir, "erl"])), + file:delete(filename:join([ErtsBinDir, "start"])), + + io:fwrite("Creating temporary directory \\"~s\\" ...~n", [TmpBinDir]), + file:make_dir(TmpBinDir), + + io:fwrite("Copying file \\"plain.boot\\" to \\"~s\\" ...~n", + [filename:join([TmpBinDir, "start.boot"])]), + copy_file("plain.boot", filename:join([TmpBinDir, "start.boot"])), + + io:fwrite("Copying files \\"epmd\\", \\"run_erl\\" and \\"to_erl\\" from \ +" + "\\"~s\\" to \\"~s\\" ...~n", + [ErtsBinDir, TmpBinDir]), + copy_file(filename:join([ErtsBinDir, "epmd"]), + filename:join([TmpBinDir, "epmd"]), [preserve]), + copy_file(filename:join([ErtsBinDir, "run_erl"]), + filename:join([TmpBinDir, "run_erl"]), [preserve]), + copy_file(filename:join([ErtsBinDir, "to_erl"]), + filename:join([TmpBinDir, "to_erl"]), [preserve]), + + StartErlDataFile = filename:join(["tmp", "releases", "start_erl.data"]), + io:fwrite("Creating \\"~s\\" ...~n", [StartErlDataFile]), + StartErlData = io_lib:fwrite("~s ~s~n", [ErtsVsn, RelVsn]), + write_file(StartErlDataFile, StartErlData), + + io:fwrite("Recreating tar file \\"~s\\" from contents in directory " + "\\"tmp\\" ...~n", [TarFileName]), + {ok, Tar} = erl_tar:open(TarFileName, [write, compressed]), + {ok, Cwd} = file:get_cwd(), + file:set_cwd("tmp"), + erl_tar:add(Tar, "bin", []), + erl_tar:add(Tar, "erts-" ++ ErtsVsn, []), + erl_tar:add(Tar, "releases", []), + erl_tar:add(Tar, "lib", []), + erl_tar:close(Tar), + file:set_cwd(Cwd), + io:fwrite("Removing directory \\"tmp\\" ...~n"), + remove_dir_tree("tmp"), + ok. + + +install(RelFileName, RootDir) -> + TarFile = RelFileName ++ ".tar.gz", + io:fwrite("Extracting ~s ...~n", [TarFile]), + extract_tar(TarFile, RootDir), + StartErlDataFile = filename:join([RootDir, "releases", "start_erl.data"]), + {ok, StartErlData} = read_txt_file(StartErlDataFile), + [ErlVsn, RelVsn| _] = string:tokens(StartErlData, " \ +"), + ErtsBinDir = filename:join([RootDir, "erts-" ++ ErlVsn, "bin"]), + BinDir = filename:join([RootDir, "bin"]), + io:fwrite("Substituting in erl.src, start.src and start_erl.src to\ +" + "form erl, start and start_erl ...\ +"), + subst_src_scripts(["erl", "start", "start_erl"], ErtsBinDir, BinDir, + [{"FINAL_ROOTDIR", RootDir}, {"EMU", "beam"}], + [preserve]), + io:fwrite("Creating the RELEASES file ...\ +"), + create_RELEASES(RootDir, + filename:join([RootDir, "releases", RelFileName])). + +%% LOCALS + +%% make_script(RelFileName) +%% +make_script(RelFileName) -> + Opts = [no_module_tests], + systools:make_script(RelFileName, Opts). + +%% make_tar(RelFileName) +%% +make_tar(RelFileName) -> + RootDir = code:root_dir(), + systools:make_tar(RelFileName, [{erts, RootDir}]). + +%% extract_tar(TarFile, DestDir) +%% +extract_tar(TarFile, DestDir) -> + erl_tar:extract(TarFile, [{cwd, DestDir}, compressed]). + +create_RELEASES(DestDir, RelFileName) -> + release_handler:create_RELEASES(DestDir, RelFileName ++ ".rel"). + +subst_src_scripts(Scripts, SrcDir, DestDir, Vars, Opts) -> + lists:foreach(fun(Script) -> + subst_src_script(Script, SrcDir, DestDir, + Vars, Opts) + end, Scripts). + +subst_src_script(Script, SrcDir, DestDir, Vars, Opts) -> + subst_file(filename:join([SrcDir, Script ++ ".src"]), + filename:join([DestDir, Script]), + Vars, Opts). + +subst_file(Src, Dest, Vars, Opts) -> + {ok, Conts} = read_txt_file(Src), + NConts = subst(Conts, Vars), + write_file(Dest, NConts), + case lists:member(preserve, Opts) of + true -> + {ok, FileInfo} = file:read_file_info(Src), + file:write_file_info(Dest, FileInfo); + false -> + ok + end. + +%% subst(Str, Vars) +%% Vars = [{Var, Val}] +%% Var = Val = string() +%% Substitute all occurrences of %Var% for Val in Str, using the list +%% of variables in Vars. +%% +subst(Str, Vars) -> + subst(Str, Vars, []). + +subst([$%, C| Rest], Vars, Result) when $A =< C, C =< $Z -> + subst_var([C| Rest], Vars, Result, []); +subst([$%, C| Rest], Vars, Result) when $a =< C, C =< $z -> + subst_var([C| Rest], Vars, Result, []); +subst([$%, C| Rest], Vars, Result) when C == $_ -> + subst_var([C| Rest], Vars, Result, []); +subst([C| Rest], Vars, Result) -> + subst(Rest, Vars, [C| Result]); +subst([], _Vars, Result) -> + lists:reverse(Result). + +subst_var([$%| Rest], Vars, Result, VarAcc) -> + Key = lists:reverse(VarAcc), + case lists:keysearch(Key, 1, Vars) of + {value, {Key, Value}} -> + subst(Rest, Vars, lists:reverse(Value, Result)); + false -> + subst(Rest, Vars, [$%| VarAcc ++ [$%| Result]]) + end; +subst_var([C| Rest], Vars, Result, VarAcc) -> + subst_var(Rest, Vars, Result, [C| VarAcc]); +subst_var([], Vars, Result, VarAcc) -> + subst([], Vars, [VarAcc ++ [$%| Result]]). + +copy_file(Src, Dest) -> + copy_file(Src, Dest, []). + +copy_file(Src, Dest, Opts) -> + {ok, InFd} = file:open(Src, [raw, binary, read]), + {ok, OutFd} = file:open(Dest, [raw, binary, write]), + do_copy_file(InFd, OutFd), + file:close(InFd), + file:close(OutFd), + case lists:member(preserve, Opts) of + true -> + {ok, FileInfo} = file:read_file_info(Src), + file:write_file_info(Dest, FileInfo); + false -> + ok + end. + +do_copy_file(InFd, OutFd) -> + case file:read(InFd, ?BUFSIZE) of + {ok, Bin} -> + file:write(OutFd, Bin), + do_copy_file(InFd, OutFd); + eof -> + ok + end. + +write_file(FName, Conts) -> + {ok, Fd} = file:open(FName, [write]), + file:write(Fd, Conts), + file:close(Fd). + +read_txt_file(File) -> + {ok, Bin} = file:read_file(File), + {ok, binary_to_list(Bin)}. + +remove_dir_tree(Dir) -> + remove_all_files(".", [Dir]). + +remove_all_files(Dir, Files) -> + lists:foreach(fun(File) -> + FilePath = filename:join([Dir, File]), + {ok, FileInfo} = file:read_file_info(FilePath), + case FileInfo#file_info.type of + directory -> + {ok, DirFiles} = file:list_dir(FilePath), + remove_all_files(FilePath, DirFiles), + file:del_dir(FilePath); + _ -> + file:delete(FilePath) + end + end, Files). + ]]> +
+ + -- cgit v1.2.3