Automatically inflect the list of applications (#5473)

Closes #5249

Author: josevalim

lib/mix/lib/mix/tasks/compile.app.ex

@@ -18,13 +18,16 @@ defmodule Mix.Tasks.Compile.App do
   function in your `mix.exs` with the following options:
 
     * `:applications` - all applications your application depends
-      on at runtime. For example, if your application depends on
-      Erlang's `:crypto`, it needs to be added to this list. Most
-      of your dependencies must be added as well (unless they're
-      a development or test dependency). Mix and other tools use this
-      list in order to properly boot your application dependencies
+      on at runtime. By default, this list is automatically inflected
+      from your dependencies. Any extra Erlang/Elixir dependency
+      must be specified in `:extra_applications`. Mix and other tools
+      use the application list in order to start your dependencies
       before starting the application itself.
 
+    * `:extra_applications` - a list of Erlang/Elixir applications
+      that you want started before your application. For example,
+      Elixir's `:logger` or Erlang's `:crypto`.
+
     * `:registered` - the name of all registered processes in the
       application. If your application defines a local GenServer
       with name `MyServer`, it is recommended to add `MyServer`
@@ -79,10 +82,10 @@ defmodule Mix.Tasks.Compile.App do
 
     if opts[:force] || Mix.Utils.stale?(sources, [target]) || modules_changed?(mods, target) do
       best_guess = [
-        vsn: to_charlist(version),
+        description: to_charlist(config[:description] || app),
         modules: mods,
-        applications: [],
         registered: [],
+        vsn: to_charlist(version),
       ]
 
       properties = if function_exported?(project, :application, 0) do
@@ -95,13 +98,7 @@ defmodule Mix.Tasks.Compile.App do
         best_guess
       end
 
-      properties = ensure_correct_properties(app, config, properties)
-
-      # Ensure we always prepend the standard application dependencies
-      properties = Keyword.update!(properties, :applications, fn apps ->
-        [:kernel, :stdlib] ++ language_app(config) ++ apps
-      end)
-
+      properties = ensure_correct_properties(properties, config)
       contents = :io_lib.format("~p.~n", [{:application, app, properties}])
 
       Mix.Project.ensure_structure()
@@ -152,13 +149,14 @@ defmodule Mix.Tasks.Compile.App do
     end
   end
 
-  defp ensure_correct_properties(app, config, properties) do
+  defp ensure_correct_properties(properties, config) do
     properties
-    |> Keyword.put_new(:description, to_charlist(config[:description] || app))
-    |> validate_properties
+    |> validate_properties!
+    |> Keyword.put_new_lazy(:applications, fn -> apps_from_prod_non_optional_deps(properties) end)
+    |> Keyword.update!(:applications, fn apps -> normalize_apps(apps, properties, config) end)
   end
 
-  defp validate_properties(properties) do
+  defp validate_properties!(properties) do
     Enum.each properties, fn
       {:description, value} ->
         unless is_list(value) do
@@ -188,13 +186,17 @@ defmodule Mix.Tasks.Compile.App do
         unless is_list(value) and Enum.all?(value, &is_atom(&1)) do
           Mix.raise "Application included applications (:included_applications) should be a list of atoms, got: #{inspect value}"
         end
+      {:extra_applications, value} ->
+        unless is_list(value) and Enum.all?(value, &is_atom(&1)) do
+          Mix.raise "Application extra applications (:extra_applications) should be a list of atoms, got: #{inspect value}"
+        end
       {:applications, value} ->
         unless is_list(value) and Enum.all?(value, &is_atom(&1)) do
-          Mix.raise "Application dependencies (:applications) should be a list of atoms, got: #{inspect value}"
+          Mix.raise "Application applications (:applications) should be a list of atoms, got: #{inspect value}"
         end
       {:env, value} ->
         unless Keyword.keyword?(value) do
-          Mix.raise "Application dependencies (:env) should be a keyword list, got: #{inspect value}"
+          Mix.raise "Application environment (:env) should be a keyword list, got: #{inspect value}"
         end
       {:start_phases, value} ->
         unless Keyword.keyword?(value) do
@@ -212,4 +214,20 @@ defmodule Mix.Tasks.Compile.App do
 
     properties
   end
+
+  defp apps_from_prod_non_optional_deps(properties) do
+    included_applications = Keyword.get(properties, :included_applications, [])
+
+    for %{app: app, opts: opts, top_level: true} <- Mix.Dep.cached,
+        Keyword.get(opts, :app, true),
+        Keyword.get(opts, :runtime, true),
+        not Keyword.get(opts, :optional, false),
+        not app in included_applications,
+        do: app
+  end
+
+  defp normalize_apps(apps, properties, config) do
+    extra = Keyword.get(properties, :extra_applications, [])
+    Enum.uniq([:kernel, :stdlib] ++ language_app(config) ++ extra ++ apps)
+  end
 end

lib/mix/lib/mix/tasks/deps.ex

@@ -81,6 +81,10 @@ defmodule Mix.Tasks.Deps do
       try to infer the type of project but it can be overridden with this
       option by setting it to `:mix`, `:rebar`, `:rebar3` or `:make`
 
+    * `:runtime` - whether the dependency is part of runtime applications.
+      Defaults to `true` which automatically adds the application to the list
+      of apps that are started automatically and included in releases
+
   ### Git options (`:git`)
 
     * `:git`        - the Git repository URI

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

@@ -113,11 +113,11 @@ defmodule Mix.Tasks.New do
   end
 
   defp otp_app(_mod, false) do
-    "    [applications: [:logger]]"
+    "    [extra_applications: [:logger]]"
   end
 
   defp otp_app(mod, true) do
-    "    [applications: [:logger],\n     mod: {#{mod}.Application, []}]"
+    "    [extra_applications: [:logger],\n     mod: {#{mod}.Application, []}]"
   end
 
   defp cd_path(".") do
@@ -218,23 +218,14 @@ defmodule Mix.Tasks.New do
   <%= if @app do %>
   ## Installation
 
-  If [available in Hex](https://hex.pm/docs/publish), the package can be installed as:
+  If [available in Hex](https://hex.pm/docs/publish), the package can be installed
+  by adding `<%= @app %>` to your list of dependencies in `mix.exs`:
 
-    1. Add `<%= @app %>` to your list of dependencies in `mix.exs`:
-
-      ```elixir
-      def deps do
-        [{:<%= @app %>, "~> 0.1.0"}]
-      end
-      ```
-
-    2. Ensure `<%= @app %>` is started before your application:
-
-      ```elixir
-      def application do
-        [applications: [:<%= @app %>]]
-      end
-      ```
+  ```elixir
+  def deps do
+    [{:<%= @app %>, "~> 0.1.0"}]
+  end
+  ```
 
   Documentation can be generated with [ExDoc](https://github.com/elixir-lang/ex_doc)
   and published on [HexDocs](https://hexdocs.pm). Once published, the docs can
@@ -255,14 +246,14 @@ defmodule Mix.Tasks.New do
   # Where 3rd-party dependencies like ExDoc output generated docs.
   /doc
 
+  # Ignore .fetch files in case you like to edit your project deps locally.
+  /.fetch
+
   # If the VM crashes, it generates a dump, let's ignore it too.
   erl_crash.dump
 
   # Also ignore archive artifacts (built via "mix archive.build").
   *.ez
-
-  # Ignore .fetch files in case you like to edit your project deps locally.
-  /.fetch
   """
 
   embed_template :mixfile, """
@@ -282,6 +273,7 @@ defmodule Mix.Tasks.New do
     #
     # Type "mix help compile.app" for more information
     def application do
+      # Specify extra applications you'll use from Erlang/Elixir
   <%= @otp_app %>
     end
 
@@ -321,6 +313,7 @@ defmodule Mix.Tasks.New do
     #
     # Type "mix help compile.app" for more information
     def application do
+      # Specify extra applications you'll use from Erlang/Elixir
   <%= @otp_app %>
     end
 

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

@@ -34,10 +34,9 @@ defmodule Mix.Tasks.App.TreeTest do
     in_fixture "umbrella_dep/deps/umbrella", fn ->
       Mix.Project.in_project(:umbrella, ".", fn _ ->
         Mix.Task.run "app.tree", ["--format", "pretty"]
+        assert_received {:mix_shell, :info, ["├── elixir"]}
         assert_received {:mix_shell, :info, ["foo"]}
-        assert_received {:mix_shell, :info, ["└── elixir"]}
-        assert_received {:mix_shell, :info, ["bar"]}
-        assert_received {:mix_shell, :info, ["└── elixir"]}
+        assert_received {:mix_shell, :info, ["    └── elixir"]}
       end)
     end
   end

lib/mix/test/mix/tasks/compile.app_test.exs

@@ -11,7 +11,30 @@ defmodule Mix.Tasks.Compile.AppTest do
 
     def application do
       [maxT: :infinity,
-       applications: [:example_app]]
+       applications: [:example_app],
+       extra_applications: [:logger]]
+    end
+  end
+
+  defmodule CustomDeps do
+    def project do
+      [app: :custom_deps, version: "0.2.0", deps: deps()]
+    end
+
+    def application do
+      [extra_applications: [:logger], included_applications: [:ok9]]
+    end
+
+    def deps do
+      [{:ok1, path: "../ok"},
+       {:ok2, path: "../ok", only: :prod},
+       {:ok3, path: "../ok", only: :dev},
+       {:ok4, path: "../ok", runtime: true},
+       {:ok5, path: "../ok", runtime: false},
+       {:ok6, path: "../ok", optional: true},
+       {:ok7, path: "../ok", optional: false},
+       {:ok8, path: "../ok", app: false},
+       {:ok9, path: "../ok"}]
     end
   end
 
@@ -48,7 +71,7 @@ defmodule Mix.Tasks.Compile.AppTest do
     end
   end
 
-  test "use custom application settings" do
+  test "uses custom application settings" do
     Mix.Project.push CustomProject
 
     in_fixture "no_mixfile", fn ->
@@ -57,11 +80,22 @@ defmodule Mix.Tasks.Compile.AppTest do
       contents = File.read!("_build/dev/lib/custom_project/ebin/custom_project.app")
       assert contents =~ "0.2.0"
       assert contents =~ "{maxT,infinity}"
-      assert contents =~ "{applications,[kernel,stdlib,elixir,example_app]}"
+      assert contents =~ "{applications,[kernel,stdlib,elixir,logger,example_app]}"
       assert contents =~ "Some UTF-8 description (uma descrição em UTF-8)"
     end
   end
 
+  test "automatically inflects applications" do
+    Mix.Project.push CustomDeps
+
+    in_fixture "no_mixfile", fn ->
+      Mix.Tasks.Compile.Elixir.run([])
+      Mix.Tasks.Compile.App.run([])
+      contents = File.read!("_build/dev/lib/custom_deps/ebin/custom_deps.app")
+      assert contents =~ "{applications,[kernel,stdlib,elixir,logger,ok1,ok3,ok4,ok7]}"
+    end
+  end
+
   test "application properties validation" do
     Mix.Project.push InvalidProject
 
@@ -90,26 +124,32 @@ defmodule Mix.Tasks.Compile.AppTest do
         Mix.Tasks.Compile.App.run([])
       end
 
+      Process.put(:application, [extra_applications: ["invalid"]])
+      message = "Application extra applications (:extra_applications) should be a list of atoms, got: [\"invalid\"]"
+      assert_raise Mix.Error, message, fn ->
+        Mix.Tasks.Compile.App.run([])
+      end
+
       Process.put(:application, [included_applications: ["invalid"]])
       message = "Application included applications (:included_applications) should be a list of atoms, got: [\"invalid\"]"
       assert_raise Mix.Error, message, fn ->
         Mix.Tasks.Compile.App.run([])
       end
 
       Process.put(:application, [applications: ["invalid"]])
-      message = "Application dependencies (:applications) should be a list of atoms, got: [\"invalid\"]"
+      message = "Application applications (:applications) should be a list of atoms, got: [\"invalid\"]"
       assert_raise Mix.Error, message, fn ->
         Mix.Tasks.Compile.App.run([])
       end
 
       Process.put(:application, [applications: nil])
-      message = "Application dependencies (:applications) should be a list of atoms, got: nil"
+      message = "Application applications (:applications) should be a list of atoms, got: nil"
       assert_raise Mix.Error, message, fn ->
         Mix.Tasks.Compile.App.run([])
       end
 
       Process.put(:application, [env: [:invalid]])
-      message = "Application dependencies (:env) should be a keyword list, got: [:invalid]"
+      message = "Application environment (:env) should be a keyword list, got: [:invalid]"
       assert_raise Mix.Error, message, fn ->
         Mix.Tasks.Compile.App.run([])
       end

lib/mix/test/mix/tasks/escript_test.exs

@@ -45,6 +45,10 @@ defmodule Mix.Tasks.EscriptTest do
        escript: [main_module: :escripttest],
        deps: [{:ok, path: fixture_path("deps_status/deps/ok")}]]
     end
+
+    def application do
+      [applications: []]
+    end
   end
 
   defmodule EscriptWithUnknownMainModule do