act

Run GitHub Actions workflows locally with Docker-based runner emulation.

24|6|Updated Nov 15, 2025
One-click install
npx skills add https://github.com/vinnie357/claude-skills --skill act
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: act
Source: https://github.com/vinnie357/claude-skills/tree/main/github/skills/act
Command: npx skills add https://github.com/vinnie357/claude-skills --skill act

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes scripts (resource) components.

What problem does it solve?

This Skill enables developers to test and debug GitHub Actions workflows locally using act, eliminating the need for constant commits and remote pushes. It drastically speeds up the development cycle for CI/CD pipelines and custom actions.

Core Features & Use Cases

  • Local Workflow Execution: Run entire GitHub Actions workflows on your machine, simulating the GitHub runner environment with Docker.
  • Offline Debugging: Debug workflow failures, test event payloads, and manage secrets locally without consuming GitHub Actions minutes.
  • Iterative Development: Rapidly develop and validate new workflows or custom actions with features like watch mode and container reuse.
  • Use Case: Before pushing a new GitHub Actions workflow to a repository, use act to run it locally with a simulated pull_request event and custom secrets to ensure it functions as expected.

Quick Start

Install 'act' using mise, then run the default push event for your workflows: mise install act act

Frequently Asked Questions about act

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I test GitHub Actions workflows locally without pushing to GitHub?

Test GitHub Actions workflows locally using act, which runs workflows on your machine with Docker-based runner emulation. act reads your .github/workflows files, pulls required images, creates isolated containers, and executes steps—letting you validate behavior and debug failures before committing.

Can I debug GitHub Actions failures without consuming GitHub Actions minutes?

Yes. act enables offline debugging by running workflows locally with custom event payloads and secrets, eliminating the need for remote pushes and CI/CD minutes. You can test different events, validate syntax, and troubleshoot issues iteratively on your machine.

What do I need to run GitHub Actions workflows locally with act?

You need Docker installed to emulate GitHub runner environments. act pulls or builds required container images, then executes workflow steps in isolated containers. Install act via mise or your package manager, then run act in your repository directory.

How do I test custom GitHub Actions or new workflows before deploying them?

Use act to run workflows locally with simulated events like pull_request or push. Test with custom secrets and event payloads to validate your custom actions and workflow logic function as expected before pushing to the repository.

Does act support iterative workflow development and rapid testing cycles?

Yes. act supports watch mode and container reuse for rapid development cycles. Run workflows repeatedly with different configurations locally, eliminating commit-and-push delays and letting you validate changes instantly.

What's the difference between testing workflows locally with act versus on GitHub runners?

act simulates GitHub runner behavior using Docker on your machine, providing immediate feedback without GitHub Actions quotas or remote latency. Local testing accelerates CI/CD development, but full integration testing on actual GitHub runners remains a final validation step.