merging release default config on app start

lib/pleroma/config/holder.ex

@@ -3,14 +3,38 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Pleroma.Config.Holder do
-  @config Pleroma.Config.Loader.load_and_merge()
+  @config Pleroma.Config.Loader.default_config()
 
-  @spec config() :: keyword()
-  def config, do: @config
+  @spec to_ets() :: true
+  def to_ets do
+    :ets.new(:default_config, [:named_table, :protected])
 
-  @spec config(atom()) :: any()
-  def config(group), do: @config[group]
+    default_config =
+      if System.get_env("RELEASE_NAME") do
+        release_config =
+          [:code.root_dir(), "releases", System.get_env("RELEASE_VSN"), "releases.exs"]
+          |> Path.join()
+          |> Pleroma.Config.Loader.read()
 
-  @spec config(atom(), atom()) :: any()
-  def config(group, key), do: @config[group][key]
+        Pleroma.Config.Loader.merge(@config, release_config)
+      else
+        @config
+      end
+
+    :ets.insert(:default_config, {:config, default_config})
+  end
+
+  @spec default_config() :: keyword()
+  def default_config, do: from_ets()
+
+  @spec default_config(atom()) :: keyword()
+  def default_config(group), do: Keyword.get(from_ets(), group)
+
+  @spec default_config(atom(), atom()) :: keyword()
+  def default_config(group, key), do: get_in(from_ets(), [group, key])
+
+  defp from_ets do
+    [{:config, default_config}] = :ets.lookup(:default_config, :config)
+    default_config
+  end
 end

lib/pleroma/config/loader.ex

@@ -13,32 +13,22 @@ defmodule Pleroma.Config.Loader do
   ]
 
   if Code.ensure_loaded?(Config.Reader) do
-    @spec load(Path.t()) :: keyword()
-    def load(path), do: Config.Reader.read!(path)
-
-    defp do_merge(conf1, conf2), do: Config.Reader.merge(conf1, conf2)
+    @reader Config.Reader
   else
     # support for Elixir less than 1.9
-    @spec load(Path.t()) :: keyword()
-    def load(path) do
-      path
-      |> Mix.Config.eval!()
-      |> elem(0)
-    end
-
-    defp do_merge(conf1, conf2), do: Mix.Config.merge(conf1, conf2)
+    @reader Mix.Config
   end
 
-  @spec load_and_merge() :: keyword()
-  def load_and_merge do
-    all_paths =
-      if Pleroma.Config.get(:release),
-        do: ["config/config.exs", "config/releases.exs"],
-        else: ["config/config.exs"]
+  @spec read(Path.t()) :: keyword()
+  def read(path), do: @reader.read!(path)
 
-    all_paths
-    |> Enum.map(&load(&1))
-    |> Enum.reduce([], &do_merge(&2, &1))
+  @spec merge(keyword(), keyword()) :: keyword()
+  def merge(c1, c2), do: @reader.merge(c1, c2)
+
+  @spec default_config() :: keyword()
+  def default_config do
+    "config/config.exs"
+    |> read()
     |> filter()
   end
 

lib/pleroma/config/transfer_task.ex

@@ -83,7 +83,7 @@ defmodule Pleroma.Config.TransferTask do
       key = ConfigDB.from_string(setting.key)
       group = ConfigDB.from_string(setting.group)
 
-      default = Pleroma.Config.Holder.config(group, key)
+      default = Pleroma.Config.Holder.default_config(group, key)
       value = ConfigDB.from_binary(setting.value)
 
       merged_value =