Sergio Chin-Sue schinsue

Deploying Elixir and Phoenix applications using Docker and Exrm

Goal

By the end of this quick guide, you will know how to compile a Phoenix app release using Exrm and run it inside a Docker container. I've found only a couple of articles that discuss getting an Elixir app up and running inside a Docker container, and even those only touched on some parts of the process. The idea is that this guide will give you a full end-to-end example of how to get all the pieces and parts working together so that you are able to deploy your Phoenix application inside a Docker container.

Assumptions

You already have a working Elixir environment with the Phoenix Framework installed
You have at least basic working knowledge of Docker, and have installed the Docker tools onto your local environment

Squashing Git Commits

The easy and flexible way

This method avoids merge conflicts if you have periodically pulled master into your branch. It also gives you the opportunity to squash into more than 1 commit, or to re-arrange your code into completely different commits (e.g. if you ended up working on three different features but the commits were not consecutive).

Note: You cannot use this method if you intend to open a pull request to merge your feature branch. This method requires committing directly to master.

Switch to the master branch and make sure you are up to date:

Elixir + Phoenix Framework + Guardian + JWT + Comeonin

Preparing environment

We need to generate secret key for development environment.

mix phoenix.gen.secret
# ednkXywWll1d2svDEpbA39R5kfkc9l96j0+u7A8MgKM+pbwbeDsuYB8MP2WUW1hf

Let's generate User model and controller.

Example of .formatter.exs file

[
  inputs: ["mix.exs", "{config,lib,test}/**/*.{ex,exs}"],
  locals_without_parens: [
    # Kernel
    inspect: 1,
    inspect: 2,

    # Phoenix

	# app deps
	sudo yum install git

	# erlang deps
	sudo yum groupinstall "Development Tools"
	sudo yum install ncurses-devel

	# erlang
	wget http://www.erlang.org/download/otp_src_18.1.tar.gz
	tar -zxvf otp_src_18.1.tar.gz

	# How to use it:
	#
	# Plug it at the end of your :browser pipeline in your Phoenix app router.ex
	# Make sure it is plugged before your session-based authentication and authorization Plugs.
	#
	# pipeline :browser do
	# plug :accepts, ["html"]
	# plug :fetch_session
	# plug :fetch_flash
	# plug :put_secure_browser_headers

	import "phoenix_html"
	import "bootstrap"
	import "jquery"
	import "toastr"

	// ...

	defmodule Boydm.Utilities.Map do

	#============================================================================
	# similar to List.meyers_difference, the below code compares two maps
	# and generates a list of actions that can be applied to the first map
	# to transform it into the second map.

	#--------------------------------------------------------
	def difference(map_1, map_2) when is_map(map_1) and is_map(map_2) do
	# remove any keys from map_1 that are simply not present (at all) in map_2