ci(rocksdb): conditionally load mnesia_rocksdb in release

Otherwise, it might not be included in the release, since it's no
longer declared as a dependency on the mria app.

mix.exs

@@ -170,8 +170,13 @@ defmodule EMQXUmbrella.MixProject do
       hocon: :load,
       emqx: :load,
       emqx_conf: :load,
-      emqx_machine: :permanent,
-      mria: :load,
+      emqx_machine: :permanent
+    ] ++
+      if(enable_rocksdb?(),
+        do: [mnesia_rocksdb: :load],
+        else: []
+      ) ++
+      [
         mnesia: :load,
         ekka: :load,
         emqx_plugin_libs: :load,
@@ -616,6 +621,11 @@ defmodule EMQXUmbrella.MixProject do
     ]) or "1" == System.get_env("BUILD_WITH_QUIC")
   end
 
+  defp enable_rocksdb?() do
+    not build_without_rocksdb?() or
+      "1" == System.get_env("BUILD_WITH_QUIC")
+  end
+
   defp pkg_vsn() do
     %{edition_type: edition_type} = check_profile!()
     basedir = Path.dirname(__ENV__.file)
@@ -657,6 +667,12 @@ defmodule EMQXUmbrella.MixProject do
     String.downcase(opt) != "false"
   end
 
+  defp build_without_rocksdb?() do
+    opt = System.get_env("BUILD_WITHOUT_ROCKSDB", "false")
+
+    String.downcase(opt) != "false"
+  end
+
   defp from_rebar_to_eex_template(str) do
     # we must not consider surrounding space in the template var name
     # because some help strings contain informative variables that

rebar.config.erl

@@ -88,6 +88,10 @@ is_quicer_supported() ->
         is_win32() orelse is_centos_6()) orelse
         "1" == os:getenv("BUILD_WITH_QUIC").
 
+is_rocksdb_supported() ->
+    not (false =/= os:getenv("BUILD_WITHOUT_ROCKSDB")) orelse
+        "1" == os:getenv("BUILD_WITH_ROCKSDB").
+
 is_macos() ->
     {unix, darwin} =:= os:type().
 
@@ -318,7 +322,10 @@ relx_apps(ReleaseType, Edition) ->
         % started by emqx_machine
         {emqx, load},
         {emqx_conf, load},
-        emqx_machine,
+        emqx_machine
+    ] ++
+        [{mnesia_rocksdb, load} || is_rocksdb_supported()] ++
+        [
             {mnesia, load},
             {ekka, load},
             {emqx_plugin_libs, load},