release-and-deployment.md

Release and Deployment

Release

The Erlang documentation describes releases as “complete systems” of one or more applications:

When you have written one or more applications, you might want to create a complete system with these applications and a subset of the Erlang/OTP applications. This is called a release.

What does that mean? Releases are packages of compiled Erlang/Elixir code (i.e. BEAM bytecode). On top of that, they contain metadata and utility scripts for launching and managing the application as a whole.

Releases may also contain the Erlang runtime (ERTS, short for Erlang Runtime System Application). Releases that include ERTS are almost completely self-contained. They have no external dependencies except for true essentials such as libc or openssl (if you're using the :crypto application).

Installing distillery

Add distillery to your application's dependencies. In the mix.exs file, add {:distillery, "~> 1.5"} to the dependencies. Then install it by running:

$ mix do deps.get, deps.compile

Creating release definition

$ mix release.init

Configuring phoenix

config :air_quality_rest_api, AirQualityRestAPI.Endpoint,
  load_from_system_env: true,
  url: [
    port: "${PORT}"
  ],
  check_origin: false,
  server: true,
  root: ".",
  cache_static_manifest: "priv/static/cache_manifest.json"

Building release

$ MIX_ENV=prod mix release --env=prod

The anatomy of a release

Let's analyze how release looks inside after bundling.

Testing release locally

$ PORT=8080 _build/prod/rel/learn-elixir-the-hard-way/bin/learn-elixir-the-hard-way foreground

Deployment

Configure runtime

Create a file called app.yaml at the root of the application directory, as it is present in this repository.

Deploy

Create new project, unless you already have one. Remember that, you need to enable billing in your project.

$ gcloud app deploy

When CLI will ask about region, I strongly recommend to use europe-west3 (which points into Frankfurt DC) as it is the closest one to us.

Review setup application

$ gcloud app browse

Cleanup

gcloud projects delete [YOUR_PROJECT_ID]

You can check [YOUR_PROJECT_ID] with command gcloud projects list.