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Elixir CI with GitHub Actions

Set up a continuous integration process for your Elixir project.

đź“…Date26 July 2020
🏷️
cidevopselixir

Prerequisites

Let’s set up a CI —Continuous Integration— process for an Elixir project using GitHub Actions.
I’ll use the JSON API we built in this tutorial.

It’s critical to have working tests on the project, otherwise what’s the point of setting CI on it, right?

So, make sure to:

  • Have a GitHub account, or create one.
  • Have a repository holding your project’s code.
  • Have tests set up in your project.

CI workflow

Let’s create a new workflow that’ll run our tests whenever we push code to main or make a pull request.

Add this to your project’s root as .github/workflows/ci.yml:

name: Elixir CI

on:
  push:
    branches: [ main ]
  pull_request:
    branches: [ main ]

jobs:
  test:
    name: Testing
    runs-on: ubuntu-latest

    services:
      db:
        image: postgres
        ports: ['5432:5432']
        env:
          POSTGRES_PASSWORD: postgres
        options: >-
          --health-cmd pg_isready
          --health-interval 10s
          --health-timeout 5s
          --health-retries 5

    steps:
    - uses: actions/checkout@v2

    - name: Set up Elixir
      uses: actions/setup-elixir@v1
      with:
        elixir-version: '1.10.4' # Define the elixir version [required]
        otp-version: '23.0.3' # Define the OTP version [required]

    - name: Restore dependencies cache
      uses: actions/cache@v2
      with:
        path: deps
        key: ${{ runner.os }}-mix-${{ hashFiles('**/mix.lock') }}
        restore-keys: ${{ runner.os }}-mix-

    - name: Output Elixir version
      run: elixir --version

    - name: Output PostgreSQL version
      run: psql --version

    #- name: Output Node.js version
    #  run: node --version

    - name: Install dependencies
      run: mix deps.get

    - name: Run tests
      run: mix test

Make some changes, commit and push to your repository.
Then go and check the Actions tab, there you’ll see the new Elixir CI workflow running!

Click on the Testing job item below Elixir CI and see how every step is run in order.

At the end you’ll see something like:

Tests pass

You can experiment and see how the CI fails by making a bad test, then pushing your code:

Tests fail

Workflow status badge

Add a workflow status badge to the README.md to show publicly the passing —or failing— status of our CI.

Example near the top of the file:

Workflow badge

Add it wherever you want.

For my user lobo-tuerto, on my repo my-phoenix-json-api, for the workflow Elixir CI the badge’s URL is:

https://github.com/lobo-tuerto/my-phoenix-json-api/workflows/Elixir%20CI/badge.svg

Add it to your README.md like this:

## MyApp

![Elixir CI][https://github.com/lobo-tuerto/my-phoenix-json-api/workflows/Elixir%20CI/badge.svg]

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