Elixir learnings - 2020 week 9

Github actions

Github actions allows you to set up arbitrary tasks that can run based upon events in Github. You can use these actions to do all sorts of things. I wanted to use these actions to setup a continuous integration workflow for my application backend written in elixir for a personal project of mine.

Continuous integration with elixir

I found a useful community action that sets up your Github workflow container for elixir and erlang dependencies for you. There are a couple of things to note about the example that's provided in the elixir setup Github actions page. By default the Phoenix example in the setup instructions is failing on the current version of Github actions for Postgres 11.

You'll get the following error:

Failed to initialize, db service is unhealthy.

Thanks to this link I was able to find the fix. You need to add an env section with the username and password that you use for your test environment.

env:
  POSTGRES_USER: postgres
  POSTGRES_PASSWORD: postgres
  POSTGRES_DB: postgres

On top of that I added a check for formatting constraints

# Check for code style formatting that doesn't match code standards
- run: mix format --check-formatted

Which yields the following for the final code to run unit tests and formatting checks in Github actions.

# .github/workflows/continuous-integration.yml

name: Continuous integration

on: push

jobs:
  test:
    runs-on: ubuntu-latest

    services:
      db:
        image: postgres:11
        ports: ["5432:5432"]
        # Add this: This is required to fix the health status problem
        env:
          POSTGRES_USER: postgres
          POSTGRES_PASSWORD: postgres
          POSTGRES_DB: postgres
        options: >-
          --health-cmd pg_isready
          --health-interval 10s
          --health-timeout 5s
          --health-retries 5

    steps:
      - uses: actions/checkout@v2
      - uses: actions/setup-elixir@v1
        with:
          otp-version: 22.2
          elixir-version: 1.9.4
      - run: mix deps.get
      - run: mix test
      # Check for code style formatting that doesn't match code standards
      - run: mix format --check-formatted

Jetbrains

Autoformat with mix format

This isn't something I didn't necessarily know about, but it's something I always find myself configuring for each project. In Jetbrains products you can set up a file watcher to run an arbitrary script based upon a file change. You can use this to autoformat your files with mix format. To do so create the following configurations in your JetBrains product of choice. I use Intellij, but this should apply to any of the JetBrains products including WebStorm, PHPStorm, RubyMine, you name it.

File watchers

.exs autoformat

.ex autoformat

Sources

1. Github actions - setup elixir
2. Postgres service never comes up healthy in action
3. mix format docs