chore(build): inject emqx_vsn to all modules as attribute

rebar.config

@@ -11,7 +11,8 @@
 {erl_opts, [warn_unused_vars,warn_shadow_vars,warn_unused_import,
             warn_obsolete_guard,compressed]}.
 
-{overrides,[{add,[{extra_src_dirs, [{"etc", [{recursive,true}]}]}]}
+{overrides,[{add,[ {extra_src_dirs, [{"etc", [{recursive,true}]}]}
+                 , {erl_opts, [{parse_transform, emqx_mod_vsn}]}]}
            ]}.
 {extra_src_dirs, [{"etc", [{recursive,true}]}]}.
 

rebar.config.erl

@@ -52,7 +52,7 @@ test_deps() ->
     ].
 
 default_compile_opts() ->
-    [compressed, deterministic, no_debug_info, warnings_as_errors, {parse_transform, mod_vsn}].
+    [compressed, deterministic, no_debug_info, warnings_as_errors, {parse_transform, emqx_mod_vsn}].
 
 profiles() ->
     [ {'emqx',          [ {erl_opts, default_compile_opts()}
@@ -67,11 +67,11 @@ profiles() ->
     , {'emqx-edge-pkg', [ {erl_opts, default_compile_opts()}
                         , {relx, relx('emqx-edge-pkg')}
                         ]}
-    , {check,           [ {erl_opts, [debug_info, warnings_as_errors, {parse_transform, mod_vsn}]}
+    , {check,           [ {erl_opts, [debug_info, warnings_as_errors, {parse_transform, emqx_mod_vsn}]}
                         ]}
     , {test,            [ {deps, test_deps()}
                         , {plugins, test_plugins()}
-                        , {erl_opts, [debug_info, {parse_transform, mod_vsn}] ++ erl_opts_i()}
+                        , {erl_opts, [debug_info, {parse_transform, emqx_mod_vsn}] ++ erl_opts_i()}
                         , {extra_src_dirs, [{"test", [{recursive,true}]}]}
                         ]}
     ].
@@ -281,6 +281,7 @@ provide_bcrypt_release(ReleaseType) ->
 compile_and_load_pase_transforms(Dir) ->
     PtFiles =
         [ "apps/emqx_rule_engine/src/emqx_rule_actions_trans.erl"
+        , "src/emqx_mod_vsn.erl"
         ],
     CompileOpts = [verbose,report_errors,report_warnings,return_errors,debug_info],
     lists:foreach(fun(PtFile) -> {ok, _Mod} = compile:file(path(Dir, PtFile), CompileOpts) end, PtFiles).

src/emqx_mod_vsn.erl

@@ -0,0 +1,40 @@
+%%--------------------------------------------------------------------
+%% Copyright (c) 2021 EMQ Technologies Co., Ltd. All Rights Reserved.
+%%
+%% Licensed 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.
+%%--------------------------------------------------------------------
+
+%% This module provides a parse_transform to inject emqx version number
+%% to all modules as a module attribute.
+%% The module attribute is so far only used for beam reload inspection.
+-module(emqx_mod_vsn).
+
+-export([parse_transform/2]).
+
+parse_transform(Form, _Opts) ->
+    case os:getenv("PKG_VSN") of
+        false -> Form;
+        Vsn -> trans(Form, {attribute, 1, emqx_vsn, Vsn})
+    end.
+
+trans(Form, Injection) ->
+    trans(Form, Injection, []).
+
+trans([], _Injection, Acc) ->
+    lists:reverse(Acc);
+trans([{eof, _} | _] = EOF, _Injection, Acc) ->
+    lists:reverse(Acc) ++ EOF;
+trans([{attribute, _, module, _} = Module | Form], Injection, Acc) ->
+    lists:reverse(Acc) ++ [Module, Injection | Form];
+trans([H | T], Injection, Acc) ->
+    trans(T, Injection, [H | Acc]).