Add Elixir sample (#8)

* Add Elixir sample

* Change Dockerfile to add files to /app

* Change README.md link to "Google App Engine"

* Add /cover, /doc, /.fetch, erl_crash.dump to .dockerignore

elixir/.dockerignore

@@ -0,0 +1,17 @@
+# The directory Mix will write compiled artifacts to.
+/_build
+
+# If you run "mix test --cover", coverage assets end up here.
+/cover
+
+# The directory Mix downloads your dependencies sources to.
+/deps
+
+# 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

elixir/.gitignore

@@ -0,0 +1,23 @@
+# The directory Mix will write compiled artifacts to.
+/_build
+
+# If you run "mix test --cover", coverage assets end up here.
+/cover
+
+# The directory Mix downloads your dependencies sources to.
+/deps
+
+# 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 mix.lock to always fetch latest dependencies
+mix.lock

elixir/Dockerfile

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+# Use the latest Elixir image from Docker Hub
+FROM elixir
+
+# Add current Mix project
+ADD . /app
+WORKDIR /app
+
+# Install package managers
+RUN mix local.hex --force
+RUN mix local.rebar --force
+
+# Fetch dependencies
+RUN mix deps.get
+
+# Compile and run the app
+ENTRYPOINT ["mix", "run", "--no-halt"]

elixir/README.md

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+# Elixir Custom Runtime for App Engine
+
+Simple sample of an [Elixir](http://elixir-lang.org) (Plug + Cowboy) app that runs on [Google App Engine](https://cloud.google.com/appengine).
+
+## Run locally
+
+    $ mix deps.get
+    $ mix run --no-halt
+
+## Deploy
+
+    $ gcloud app deploy

elixir/app.yaml

@@ -0,0 +1,2 @@
+runtime: custom
+env: flex

elixir/config/config.exs

@@ -0,0 +1 @@
+use Mix.Config

elixir/lib/my_app.ex

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+defmodule MyApp do
+  use Application
+
+  def start(_type, _args) do
+    Plug.Adapters.Cowboy.http(MyApp.Router, [], [port: 8080])
+  end
+end

elixir/lib/my_app/router.ex

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+defmodule MyApp.Router do
+  import Plug.Conn
+
+  def init(opts), do: opts
+
+  def call(%Plug.Conn{request_path: "/_ah/health"} = conn, _opts) do
+    send_resp(conn, 200, "👌")
+  end
+  def call(conn, _opts) do
+    send_resp(conn, 200, "Elixir running on Google App Engine!")
+  end
+end

elixir/mix.exs

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+defmodule MyApp.Mixfile do
+  use Mix.Project
+
+  def project do
+    [app: :my_app,
+     version: "0.1.0",
+     elixir: "~> 1.4",
+     build_embedded: Mix.env == :prod,
+     start_permanent: Mix.env == :prod,
+     deps: deps()]
+  end
+
+  def application do
+    [mod: {MyApp, []}]
+  end
+
+  defp deps do
+    [{:plug, "~> 1.0"},
+     {:cowboy, "~> 1.0"}]
+  end
+end