Matrix Builds in GitHub Actions

1. Introduction

Matrix builds allow you to run a set of jobs in parallel, each with different configurations. This feature is particularly useful for testing across multiple environments, dependencies, or configurations quickly.

2. Key Concepts

Matrix Strategy

A matrix strategy enables you to define multiple configurations for a job by specifying different parameters in your workflow file.

Jobs

Jobs are defined in the workflow and can run in parallel or sequentially based on dependencies.

3. Configuration Steps

Follow these steps to set up matrix builds in your GitHub Actions workflow:

Define a workflow file in your repository.

Specify the matrix strategy under the job configuration.

Use the matrix variables in the steps of your job.

Example Workflow

yaml
name: CI

on: [push]

jobs:
  build:
    runs-on: ubuntu-latest
    strategy:
      matrix:
        node-version: [12, 14, 16]

    steps:
      - name: Checkout code
        uses: actions/checkout@v2

      - name: Set up Node.js
        uses: actions/setup-node@v2
        with:
          node-version: ${{ matrix.node-version }}

      - name: Install dependencies
        run: npm install

      - name: Run tests
        run: npm test

4. Best Practices

Always ensure that your jobs are independent. If jobs depend on each other, consider using the needs keyword.

Keep matrix configurations simple to avoid long build times.
Use caching strategies to speed up builds.
Limit the number of matrix combinations to prevent overload.

5. FAQ

What is a matrix build?

A matrix build allows you to run multiple jobs in parallel with varying configurations defined in a matrix strategy.

Can I use matrix builds for deployment?

Yes, matrix builds can be utilized for deployments, enabling you to deploy across different environments simultaneously.

How do I limit the number of matrix combinations?

You can limit combinations by specifying only the necessary parameters in your matrix strategy.