import_config/1 now accepts wildcards

Author: José Valim

lib/mix/lib/mix/config.ex

@@ -110,14 +110,13 @@ defmodule Mix.Config do
 
   Or to import files from children in umbrella projects:
 
-      import_config "../apps/child/config/config.exs"
+      import_config "../apps/*/config/config.exs"
 
   """
   defmacro import_config(file) do
     quote do
       var!(config, Mix.Config) =
-        Mix.Config.merge(var!(config, Mix.Config),
-                         Mix.Config.read!(Path.expand(unquote(file), __DIR__)))
+        Mix.Config.read_wildcard!(Path.expand(unquote(file), __DIR__), var!(config, Mix.Config))
     end
   end
 
@@ -140,6 +139,17 @@ defmodule Mix.Config do
     end
   end
 
+  @doc """
+  Reads many configuration files given by wildcard into a single config.
+  """
+  def read_wildcard!(path, config) do
+    paths = case Path.wildcard(path) do
+      [] -> [path]
+      o  -> o
+    end
+    Enum.reduce(paths, config, &merge(&2, read!(&1)))
+  end
+
   @doc """
   Persists the given configuration by modifying
   the configured applications environment.

lib/mix/lib/mix/tasks/new.ex

@@ -314,13 +314,22 @@ defmodule Mix.Tasks.New do
   """
 
   embed_template :config_umbrella, ~S"""
+  # This file is responsible for configuring your application
+  # and its dependencies with the aid of the Mix.Config module.
+  use Mix.Config
+
+  # The configuration defined here will only affect the dependencies
+  # in the apps directory when commands are executed from the umbrella
+  # project. For this reason, it is preferred to configure each child
+  # application directly and import its configuration, as done below.
+  import_config "../apps/*/config/config.exs"
 
-  # Finally, note that configuration defined in children projects
-  # inside apps/ are not automatically available to the umbrella parent.
-  # They can, however, be easily imported:
+  # Sample configuration (overrides the imported configuration above):
   #
-  #     import_config "../apps/foo/config/config.exs"
-  #     import_config "../apps/bar/config/config.exs"
+  #     config :logger, :console,
+  #       level: :info,
+  #       format: "$date $time [$level] $metadata$message\n",
+  #       metadata: [:user_id]
   """
 
   embed_template :lib, """

lib/mix/test/mix/config_test.exs

@@ -38,6 +38,20 @@ defmodule Mix.ConfigTest do
     assert var!(config, Mix.Config) == [my_app: [key: :value]]
   end
 
+  test "import_config/1 with wildcards" do
+    use Mix.Config
+    import_config fixture_path("configs/good_*.exs")
+    assert var!(config, Mix.Config) == [my_app: [key: :value]]
+  end
+
+  test "import_config/1 with bad path" do
+    use Mix.Config
+
+    assert_raise Mix.Config.LoadError, ~r"could not load config", fn ->
+      import_config fixture_path("configs/unknown.exs")
+    end
+  end
+
   test "read!/1" do
     assert Mix.Config.read!(fixture_path("configs/good_config.exs")) ==
            [my_app: [key: :value]]