act

Overview

Act runs GitHub Actions workflows locally using Docker. Test and debug CI pipelines without pushing to GitHub. Supports most GitHub Actions features.

Instructions

Step 1: Install

brew install act

Step 2: Run Workflows

act                          # run push event
act pull_request             # run PR event
act -j test                  # run specific job
act -W .github/workflows/ci.yml  # specific workflow
act --secret-file .env.secrets   # with secrets

Step 3: Configuration

# .actrc — Default settings
-P ubuntu-latest=catthehacker/ubuntu:act-latest
--env-file .env

Step 4: Debug

act -n    # dry run
act -v    # verbose
act -l    # list workflows

Guidelines

• First run downloads Docker images (~1-3GB).
• Not all GitHub Actions features work locally (e.g., OIDC tokens).
• Use micro images for faster runs.
• Great for iterating on CI without waiting for GitHub runners.