docker-phoenix-dev

Creating a Dockerized Phoenix development environment.

Step a1: Clone the Project

The default values in this project will create a basic working environment.

• Review the contents of Dockerfile
• Review the contents of docker-compose, rename as necessary

Step a2: Build the image

$ docker-compose build 

Step a3: create "src" directory and command "mix" alias

The "src" directory will contain the Phoenix application.

$ mkdir src

Create a "mix" alias to run the Elixir commands. (Only if you have not previously added the alias function from the later steps)

$ alias mix="docker-compose run --rm phoenix mix"

The "src/" directory has been .gitignore'd, so review that file to make sure it matches your intentions

Step a4: Initialize and configure a new Phoenix application

This command will create a new Phoenix apllication called "hello" under the "./src" directory, which will be mounted inside the container under "/app" (the default working directory).

$ mix phx.new . --app hello

In the configuration file src/config/dev.exs change the database hostname and endpoint IP.

...
# Configure your database
...
hostname: "db",
...
config :hello, HelloWeb.Endpoint,
  # Binding to loopback ipv4 address prevents access from other machines.
  # Change to `ip: {0, 0, 0, 0}` to allow access from other machines.
  http: [ip: {0, 0, 0, 0}, port: 4000],
...

Initialize the database with Ecto

Aliasing: Add the appropriate .alias-mix-file to the src directory

$ cd src
$ mix ecto.create

If you copied an existing application, run the database migrations now.

$ mix ecto.migrate

Step a5: Start the application

$ cd ..
$ docker-compose up

Once started application will be available at http://localhost:4000

Acknowledgement

The above information is mostly from the following post: https://medium.com/swlh/use-docker-to-create-an-elixir-phoenix-development-environment-e1a81def1d2e

Aliasing

Setting that alias from earlier is going to get old pretty quickly, also you might not want your mix command to be aliased system wide.

Let's set things up so you can configure where it get's aliased.

Step b1: Add the following to your Terminal Profile file

These steps have been tested using ZSH and by editing the .zshrc file.

mixes()
{
  # Check if a file called .alias-docker-phoenix-mix exists in the current directory
  if [ -f ./.alias-docker-phoenix-mix ] ; then
      # Run the phoenix mix command in the phoenix Docker container
      docker-compose run --rm phoenix mix "$@"
  else
      # Run the usual mix command
      mix "$@"
  fi
}

alias mix=mixes

iexes()
{
  # Check if a file called .alias-docker-phoenix-mix exists in the current directory
  if [ -f ./.alias-docker-phoenix-mix ] ; then
      # Run the elixir iex command in the phoenix Docker container
      docker-compose run --rm phoenix iex "$@"
  else
      # Run the usual mix command
      iex "$@"
  fi
}

alias iex=iexes

Step b2: Create the .alias-docker-phoenix-mix file

Navigate to your project directory and create the file

touch .alias-docker-phoenix-mix

Step b3: Apply the new configuration and test

# Apply Configuration
source ~/.zshrc 

# Should run in the Docker container
mix help

Creating a new application

The above steps will prove that the Docker imaged Phoenix app works.

Now follow these steps to start creating your own application using this structure, please replace "new-project" with your actual-project:

Step c1: Create your project directory

mkdir new-project

Step c2: Configure Docker

Copy these files to your new project and confirm the contents:

• docker-compose.yml : Confirm the service, database images names and port numbers
• Dockerfile: Confirm the port numbers

Step c3: Add the alias-phoenix to your project directory

# From the project root
touch .alias-docker-new-project-mix

# Updating the functions in terminal profile
mixes()
{
  # Check if a file called .alias-docker-phoenix-mix exists in the current directory
  if [ -f ./.alias-docker-phoenix-mix ] ; then
      # Run the phoenix mix command in the phoenix Docker container
      docker-compose run --rm phoenix mix "$@"
  elif [ -f ./.alias-docker-new-project-mix ] ; then
      # Run the phoenix mix command in the new-project Docker container
      docker-compose run --rm new-project mix "$@"
  else
      # Run the usual mix command
      mix "$@"
  fi
}

iexes()
{
  # Check if a file called .alias-docker-phoenix-mix exists in the current directory
  if [ -f ./.alias-docker-phoenix-mix ] ; then
      # Run the elixir iex command in the phoenix Docker container
      docker-compose run --rm phoenix iex "$@"
  elif [ -f ./.alias-docker-new-project-mix ] ; then
      # Run the elixir iex command in the new-project Docker container
      docker-compose run --rm new-project iex "$@"      
  else
      # Run the usual mix command
      iex "$@"
  fi
}

alias iex=iexes

# Apply the new Configuration
source ~/.zshrc 

Step c4: Build and initialize the project

Work through Steps a2 - a5 replacing the project name where necessary and remembering you don't need the alias bit.