Make config/runtime.exs deep merge, closes #10365

Author: josevalim

lib/mix/lib/mix/cli.ex

@@ -146,7 +146,7 @@ defmodule Mix.CLI do
     path = Path.join(Mix.Utils.mix_config(), "config.exs")
 
     if File.regular?(path) do
-      Mix.Tasks.Loadconfig.load_imports(path)
+      Mix.Tasks.Loadconfig.load_compile(path)
     end
   end
 

lib/mix/lib/mix/tasks/app.config.ex

@@ -34,7 +34,7 @@ defmodule Mix.Tasks.App.Config do
     runtime = config[:config_path] |> Path.dirname() |> Path.join("runtime.exs")
 
     if File.exists?(runtime) do
-      Mix.Tasks.Loadconfig.load_file(runtime)
+      Mix.Tasks.Loadconfig.load_runtime(runtime)
     end
 
     if opts[:preload_modules] do

lib/mix/lib/mix/tasks/loadconfig.ex

@@ -29,34 +29,42 @@ defmodule Mix.Tasks.Loadconfig do
 
     case args do
       [] -> load_default()
-      [file] -> load_imports(file)
+      [file] -> load_compile(file)
     end
   end
 
   defp load_default do
     config = Mix.Project.config()
 
     if File.regular?(config[:config_path]) or config[:config_path] != "config/config.exs" do
-      load_imports(config[:config_path])
+      load_compile(config[:config_path])
     else
       []
     end
   end
 
   @doc false
-  def load_imports(file) do
+  # Loads compile-time configuration, they support imports, and are not deep merged.
+  def load_compile(file) do
     {config, files} = Config.Reader.read_imports!(file, env: Mix.env(), target: Mix.target())
     Mix.ProjectStack.loaded_config(persist_apps(config, file), files)
     config
   end
 
   @doc false
-  def load_file(file) do
+  # Loads runtime configuration, they do not support imports, and are deep merged.
+  def load_runtime(file) do
     config = Config.Reader.read!(file, env: Mix.env(), target: Mix.target(), imports: :disabled)
-    Mix.ProjectStack.loaded_config(persist_apps(config, file), [])
+    Mix.ProjectStack.loaded_config(persist_apps(hydrate_apps(config), file), [])
     config
   end
 
+  defp hydrate_apps(config) do
+    for {app, pairs} <- config do
+      hd(Config.Reader.merge([{app, Application.get_all_env(app)}], [{app, pairs}]))
+    end
+  end
+
   defp persist_apps(config, file) do
     Application.put_all_env(config, persistent: true)
     apps = Keyword.keys(config)

lib/mix/lib/mix/tasks/run.ex

@@ -154,7 +154,13 @@ defmodule Mix.Tasks.Run do
 
   defp process_config(opts) do
     for {:config, value} <- opts do
-      Mix.Tasks.Loadconfig.load_imports(value)
+      # TODO: Remove on v2.0.
+      IO.warn(
+        "the --config flag is deprecated. If you need to handle multiple configurations, " <>
+          "it is preferable to dynamically import them in your config files"
+      )
+
+      Mix.Tasks.Loadconfig.load_compile(value)
     end
 
     :ok

lib/mix/test/mix/tasks/app.config_test.exs

@@ -17,11 +17,13 @@ defmodule Mix.Tasks.App.ConfigTest do
       File.write!("config/config.exs", """
       import Config
       config :sample, from_compile: :compile, from_runtime: :compile
+      config :sample, :nested, from_compile: :compile, from_runtime: :compile
       """)
 
       File.write!("config/runtime.exs", """
       import Config
       config :sample, from_runtime: :runtime
+      config :sample, :nested, from_compile: :compile, from_runtime: :compile
       """)
 
       Mix.Task.run("loadconfig")
@@ -30,10 +32,12 @@ defmodule Mix.Tasks.App.ConfigTest do
       assert Application.get_all_env(:sample) |> Enum.sort() == [
                from_compile: :compile,
                from_env: :env,
-               from_runtime: :runtime
+               from_runtime: :runtime,
+               nested: [from_compile: :compile, from_runtime: :compile]
              ]
     end)
   after
+    Application.delete_env(:sample, :nested, persistent: true)
     Application.delete_env(:sample, :from_env, persistent: true)
     Application.delete_env(:sample, :from_compile, persistent: true)
     Application.delete_env(:sample, :from_runtime, persistent: true)

lib/mix/test/mix/tasks/release_test.exs

@@ -359,14 +359,23 @@ defmodule Mix.Tasks.ReleaseTest do
       config = [releases: [runtime_config: [reboot_system_after_config: true]]]
 
       Mix.Project.in_project(:release_test, ".", config, fn _ ->
+        File.write!("config/config.exs", """
+        #{File.read!("config/config.exs")}
+        config :release_test, :runtime, keep: :static, override: :static
+        """)
+
         File.write!("config/runtime.exs", """
         import Config
 
         if System.get_env("RELEASE_MODE") == nil do
           raise "file should not be loaded while assembling release"
         end
 
-        config :release_test, :runtime, {:was_set, config_env(), config_target()}
+        config :release_test, :runtime,
+          override: :runtime,
+          config_env: config_env(),
+          config_target: config_target()
+
         config :release_test, :encoding, {:runtime, :time_μs, :"£", "£", '£'}
         """)
 
@@ -401,7 +410,9 @@ defmodule Mix.Tasks.ReleaseTest do
                  release_mode: "embedded",
                  release_node: "runtime_config",
                  release_vsn: "0.1.0",
-                 runtime_config: {:ok, {:was_set, :dev, :host}},
+                 runtime_config:
+                   {:ok,
+                    [keep: :static, override: :runtime, config_env: :dev, config_target: :host]},
                  static_config: {:ok, :was_set},
                  sys_config_env: sys_config_env,
                  sys_config_init: sys_config_init

lib/mix/test/mix/tasks/run_test.exs

@@ -3,24 +3,10 @@ Code.require_file("../../test_helper.exs", __DIR__)
 defmodule Mix.Tasks.RunTest do
   use MixTest.Case
 
-  import ExUnit.CaptureIO
-
   setup do
     Mix.Project.push(MixTest.Case.Sample)
   end
 
-  test "loads configuration", context do
-    in_tmp(context.test, fn ->
-      config = fixture_path("configs/good_config.exs")
-      expr = "IO.puts(Application.get_env(:my_app, :key))"
-
-      assert capture_io(fn -> Mix.Task.run("run", ["--config", config, "--eval", expr]) end) ==
-               "value\n"
-    end)
-  after
-    Application.delete_env(:my_app, :key)
-  end
-
   test "run requires files before evaling commands", context do
     git_repo = fixture_path("git_repo/lib/git_repo.ex")