Add 'generate-upgrade' command

To support OTP release upgrades I have added support for building
upgrade packages. Support for this is included in the
rebar_upgrade module, specifically generate_upgrade/2. It requires
one variable to be set on the command line 'previous_release' which
is the absolute path or relative path from 'rel/' to the previous
release one is upgrading from. Running an upgrade will create the
needed files, including a relup and result in a tarball containing
the upgrade being written to 'rel/'. When done it cleans up the
temporary files systools created.

Usage:
$ rebar generate-upgrade previous_release=/path/to/old/version

This also includes a dummy application that can be used to test
upgrades as well as an example.

Special thanks to Daniel Reverri, Jesper Louis Andersen and
Richard Jones for comments and patches.

2 files changed, 210 insertions, 2 deletions

diff --git a/src/rebar.erl b/src/rebar.erl
index 1b502b1..6c99ab5 100644
--- a/src/rebar.erl
+++ b/src/rebar.erl
@@ -211,6 +211,8 @@ delete-deps                          Delete fetched dependencies
 
 generate    [dump_spec=0/1]          Build release with reltool
 
+generate-upgrade  [previous_release=path]  Build an upgrade package
+
 eunit       [suite=foo]              Run eunit [test/foo_tests.erl] tests
 ct          [suite=] [case=]         Run common_test suites in ./test
 
@@ -264,8 +266,8 @@ filter_flags([Item | Rest], Commands) ->
 command_names() ->
     ["build-plt", "check-deps", "check-plt", "clean", "compile", "create",
      "create-app", "create-node", "ct", "delete-deps", "dialyze", "doc",
-     "eunit", "generate", "get-deps", "help", "list-templates", "update-deps",
-     "version", "xref"].
+     "eunit", "generate", "generate-upgrade", "get-deps", "help",
+     "list-templates", "update-deps", "version", "xref"].
 
 unabbreviate_command_names([]) ->
     [];
diff --git a/src/rebar_upgrade.erl b/src/rebar_upgrade.erl
new file mode 100644
index 0000000..4c0d2f7
--- /dev/null
+++ b/src/rebar_upgrade.erl
@@ -0,0 +1,206 @@
+%% -*- tab-width: 4;erlang-indent-level: 4;indent-tabs-mode: nil -*-
+%% ex: ts=4 sw=4 et
+%% -------------------------------------------------------------------
+%%
+%% rebar: Erlang Build Tools
+%%
+%% Copyright (c) 2011 Joe Williams <joe@joetify.com>
+%%
+%% Permission is hereby granted, free of charge, to any person obtaining a copy
+%% of this software and associated documentation files (the "Software"), to deal
+%% in the Software without restriction, including without limitation the rights
+%% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+%% copies of the Software, and to permit persons to whom the Software is
+%% furnished to do so, subject to the following conditions:
+%%
+%% The above copyright notice and this permission notice shall be included in
+%% all copies or substantial portions of the Software.
+%%
+%% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+%% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+%% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+%% AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+%% LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+%% OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+%% THE SOFTWARE.
+%% -------------------------------------------------------------------
+
+-module(rebar_upgrade).
+
+-include("rebar.hrl").
+-include_lib("kernel/include/file.hrl").
+
+-export(['generate-upgrade'/2]).
+
+%% public api
+
+'generate-upgrade'(_Config, ReltoolFile) ->
+    case rebar_config:get_global(previous_release, false) of
+        false ->
+            ?ABORT("previous_release=PATH is required to "
+                   "create upgrade package~n", []);
+        OldVerPath ->
+            %% Run checks to make sure that building a package is possible
+            {NewName, NewVer} = run_checks(OldVerPath, ReltoolFile),
+            NameVer = NewName ++ "_" ++ NewVer,
+
+            %% Save the code path prior to doing anything
+            OrigPath = code:get_path(),
+
+            %% Prepare the environment for building the package
+            ok = setup(OldVerPath, NewName, NewVer, NameVer),
+
+            %% Build the package
+            run_systools(NameVer, NewName),
+
+            %% Boot file changes
+            boot_files(NewVer, NewName),
+
+            %% Extract upgrade and tar it back up with changes
+            make_tar(NameVer),
+
+            %% Clean up files that systools created
+            ok = cleanup(NameVer, NewName, NewVer),
+
+            %% Restore original path
+            true = code:set_path(OrigPath),
+
+            ok
+    end.
+
+%% internal api
+
+run_checks(OldVerPath, ReltoolFile) ->
+    true = prop_check(filelib:is_dir(OldVerPath),
+                      "Release directory doesn't exist (~p)~n", [OldVerPath]),
+
+    {Name, Ver} = get_release_name(ReltoolFile),
+
+    NamePath = filename:join([".", Name]),
+    true = prop_check(filelib:is_dir(NamePath),
+                      "Release directory doesn't exist (~p)~n", [NamePath]),
+
+    {NewName, NewVer} = get_release_version(Name, NamePath),
+    {OldName, OldVer} = get_release_version(Name, OldVerPath),
+
+    true = prop_check(NewName == OldName,
+                      "New and old .rel release names do not match~n", []),
+    true = prop_check(Name == NewName,
+                      "Reltool and .rel release names do not match~n", []),
+    true = prop_check(NewVer =/= OldVer,
+                      "New and old .rel contain the same version~n", []),
+    true = prop_check(Ver == NewVer,
+                      "Reltool and .rel versions do not match~n", []),
+
+    {NewName, NewVer}.
+
+get_release_name(ReltoolFile) ->
+    %% expect sys to be the first proplist in reltool.config
+    case file:consult(ReltoolFile) of
+        {ok, [{sys, Config}| _]} ->
+            %% expect the first rel in the proplist to be the one you want
+            {rel, Name, Ver, _} = proplists:lookup(rel, Config),
+            {Name, Ver};
+        _ ->
+            ?ABORT("Failed to parse ~s~n", [ReltoolFile])
+    end.
+
+get_release_version(Name, Path) ->
+    [RelFile] = filelib:wildcard(filename:join([Path, "releases", "*",
+                                                Name ++ ".rel"])),
+    [BinDir|_] = re:replace(RelFile, Name ++ "\\.rel", ""),
+    {ok, [{release, {Name1, Ver}, _, _}]} =
+        file:consult(filename:join([binary_to_list(BinDir),
+                                    Name ++ ".rel"])),
+    {Name1, Ver}.
+
+prop_check(true, _, _) -> true;
+prop_check(false, Msg, Args) -> ?ABORT(Msg, Args).
+
+setup(OldVerPath, NewName, NewVer, NameVer) ->
+    NewRelPath = filename:join([".", NewName]),
+    Src = filename:join([NewRelPath, "releases",
+                         NewVer, NewName ++ ".rel"]),
+    Dst = filename:join([".", NameVer ++ ".rel"]),
+    {ok, _} = file:copy(Src, Dst),
+    ok = code:add_pathsa(
+           lists:append([
+                         filelib:wildcard(filename:join([OldVerPath,
+                                                         "releases", "*"])),
+                         filelib:wildcard(filename:join([OldVerPath,
+                                                         "lib", "*", "ebin"])),
+                         filelib:wildcard(filename:join([NewRelPath,
+                                                         "lib", "*", "ebin"])),
+                         filelib:wildcard(filename:join([NewRelPath, "*"]))
+                        ])).
+
+run_systools(NewVer, Name) ->
+    Opts = [silent],
+    NameList = [Name],
+    case systools:make_relup(NewVer, NameList, NameList, Opts) of
+        {error, _, _Message} ->
+            ?ABORT("Systools aborted with: ~p~n", [_Message]);
+        _ ->
+            ?DEBUG("Relup created~n", []),
+            case systools:make_script(NewVer, Opts) of
+                {error, _, _Message1} ->
+                    ?ABORT("Systools aborted with: ~p~n", [_Message1]);
+                _ ->
+                    ?DEBUG("Script created~n", []),
+                    case systools:make_tar(NewVer, Opts) of
+                        {error, _, _Message2} ->
+                            ?ABORT("Systools aborted with: ~p~n", [_Message2]);
+                        _ ->
+                            ok
+                    end
+            end
+    end.
+
+boot_files(Ver, Name) ->
+    ok = file:make_dir(filename:join([".", "releases"])),
+    ok = file:make_dir(filename:join([".", "releases", Ver])),
+    ok = file:make_symlink(filename:join(["start.boot"]),
+                           filename:join([".", "releases", Ver, Name ++ ".boot"])),
+    {ok, _} = file:copy(filename:join([".", Name, "releases", Ver, "start_clean.boot"]),
+                        filename:join([".", "releases", Ver, "start_clean.boot"])).
+
+make_tar(NameVer) ->
+    Filename = NameVer ++ ".tar.gz",
+    ok = erl_tar:extract(Filename, [compressed]),
+    ok = file:delete(Filename),
+    {ok, Tar} = erl_tar:open(Filename, [write, compressed]),
+    ok = erl_tar:add(Tar, "lib", []),
+    ok = erl_tar:add(Tar, "releases", []),
+    ok = erl_tar:close(Tar),
+    ?CONSOLE("~s upgrade package created~n", [NameVer]).
+
+cleanup(NameVer, Name, Ver) ->
+    ?DEBUG("Removing files needed for building the upgrade~n", []),
+    Files = [
+             filename:join([".", "releases", Ver, Name ++ ".boot"]),
+             filename:join([".", NameVer ++ ".rel"]),
+             filename:join([".", NameVer ++ ".boot"]),
+             filename:join([".", NameVer ++ ".script"]),
+             filename:join([".", "relup"])
+            ],
+    [ok = file:delete(F) || F <- Files],
+
+    ok = remove_dir_tree("releases"),
+    ok = remove_dir_tree("lib").
+
+%% taken from http://www.erlang.org/doc/system_principles/create_target.html
+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).