feat(scripts): Add an appup helper script

scripts/update_appup.escript

@@ -0,0 +1,72 @@
+#!/usr/bin/env -S escript -c
+%% A script that adds changed modules to the corresponding appup files
+
+main(_Args) ->
+    ChangedFiles = string:lexemes(os:cmd("git diff --name-only origin/master..HEAD"), "\n"),
+    AppModules = group_modules(lists:filtermap(fun filter_erlang_modules/1, ChangedFiles)),
+    io:format("Changed modules: ~p~n", [AppModules]),
+    _ = maps:map(fun process_app/2, AppModules),
+    ok.
+
+process_app(App, Modules) ->
+    AppupFiles = filelib:wildcard(lists:concat(["{src,apps,lib-*}/**/", App, ".appup.src"])),
+    case AppupFiles of
+        [AppupFile] ->
+          update_appup(AppupFile, Modules);
+        []          ->
+          io:format("~nWARNING: Please create an stub appup src file for ~p~n", [App])
+    end.
+
+filter_erlang_modules(Filename) ->
+    case lists:reverse(filename:split(Filename)) of
+        [Module, "src"] ->
+            erl_basename("emqx", Module);
+        [Module, "src", App|_] ->
+            erl_basename(App, Module);
+        [Module, _, "src", App|_] ->
+            erl_basename(App, Module);
+        _ ->
+            false
+    end.
+
+erl_basename(App, Name) ->
+    case filename:basename(Name, ".erl") of
+        Name   -> false;
+        Module -> {true, {list_to_atom(App), list_to_atom(Module)}}
+    end.
+
+group_modules(L) ->
+    lists:foldl(fun({App, Mod}, Acc) ->
+                        maps:update_with(App, fun(Tl) -> [Mod|Tl] end, [Mod], Acc)
+                end, #{}, L).
+
+update_appup(File, Modules) ->
+    io:format("~nUpdating appup: ~p~n", [File]),
+    {_, Upgrade0, Downgrade0} = read_appup(File),
+    Upgrade = update_actions(Modules, Upgrade0),
+    Downgrade = update_actions(Modules, Downgrade0),
+    IOList = io_lib:format("%% -*- mode: erlang -*-
+{VSN,~n  ~p,~n  ~p}.~n", [Upgrade, Downgrade]),
+    ok = file:write_file(File, IOList).
+
+update_actions(Modules, Versions) ->
+    lists:map(fun(L) -> do_update_actions(Modules, L) end, Versions).
+
+do_update_actions(_, Ret = {<<".*">>, _}) ->
+    Ret;
+do_update_actions(Modules, {Vsn, Actions}) ->
+    {Vsn, add_modules(Modules, Actions)}.
+
+add_modules(NewModules, OldActions) ->
+    OldModules = lists:map(fun(It) -> element(2, It) end, OldActions),
+    Modules = NewModules -- OldModules,
+    OldActions ++ [{load_module, M, brutal_purge, soft_purge, []} || M <- Modules].
+
+read_appup(File) ->
+    {ok, Bin0} = file:read_file(File),
+    %% Hack:
+    Bin1 = re:replace(Bin0, "VSN", "\"VSN\""),
+    TmpFile = filename:join("/tmp", filename:basename(File)),
+    ok = file:write_file(TmpFile, Bin1),
+    {ok, [Terms]} = file:consult(TmpFile),
+    Terms.