chore(script): Add a script to split emqx.conf

.gitignore

@@ -45,3 +45,4 @@ emqx_dialyzer_*_plt
 */emqx_dashboard/priv/www
 dist.zip
 scripts/git-token
+etc/*.seg

scripts/split-config.escript

@@ -0,0 +1,62 @@
+#!/usr/bin/env escript
+
+%% This script reads up emqx.conf and split the sections
+%% and dump sections to separate files.
+%% Sections are grouped between CONFIG_SECTION_BGN and
+%% CONFIG_SECTION_END pairs
+%%
+%% NOTE: this feature is so far not used in opensource
+%% edition due to backward-compatibility reasons.
+
+-mode(compile).
+
+-define(BASE, <<"emqx">>).
+
+main(_) ->
+    {ok, Bin} = file:read_file("etc/emqx.conf"),
+    Lines = binary:split(Bin, <<"\n">>, [global]),
+    Sections0 = parse_sections(Lines),
+    Sections = lists:filter(fun({<<"modules">>, _}) -> false;
+                               (_) -> true
+                            end, Sections0),
+    ok = dump_sections(Sections).
+
+parse_sections(Lines) ->
+    {ok, P} = re:compile("#+\s*CONFIG_SECTION_(BGN|END)\s*=\s*([^\s-]+)\s*="),
+    Parser =
+        fun(Line) ->
+                case re:run(Line, P, [{capture, all_but_first, binary}]) of
+                    {match, [<<"BGN">>, Name]} -> {section_bgn, Name};
+                    {match, [<<"END">>, Name]} -> {section_end, Name};
+                    nomatch -> continue
+                end
+        end,
+    parse_sections(Lines, Parser, ?BASE, #{?BASE => []}).
+
+parse_sections([], _Parse, _Section, Sections) ->
+    lists:map(fun({N, Lines}) -> {N, lists:reverse(Lines)} end,
+              maps:to_list(Sections));
+parse_sections([Line | Lines], Parse, Section, Sections) ->
+    case Parse(Line) of
+        {section_bgn, Name} ->
+            ?BASE = Section, %% assert
+            true = (Name =/= ?BASE), %% assert
+            false = maps:is_key(Name, Sections), %% assert
+            Include = iolist_to_binary(["include {{ platform_etc_dir }}/", Name, ".conf"]),
+            Base = maps:get(?BASE, Sections),
+            NewSections = Sections#{?BASE := [Include | Base], Name => []},
+            parse_sections(Lines, Parse, Name, NewSections);
+        {section_end, Name} ->
+            true = (Name =:= Section), %% assert
+            parse_sections(Lines, Parse, ?BASE, Sections);
+        continue ->
+            Acc = maps:get(Section, Sections),
+            parse_sections(Lines, Parse, Section, Sections#{Section => [Line | Acc]})
+    end.
+
+dump_sections([]) -> ok;
+dump_sections([{Name, Lines0} | Rest]) ->
+    Filename = filename:join(["etc", iolist_to_binary([Name, ".conf.seg"])]),
+    Lines = [[L, "\n"] || L <- Lines0],
+    ok = file:write_file(Filename, Lines),
+    dump_sections(Rest).