act-docker-setup

Use act to run GitHub Actions workflows on your local machine. Act simulates the GitHub Actions runner environment, letting you test workflows with Docker before committing. This catches errors early and speeds up development cycles without triggering CI/CD pipelines.

Act provides runner images in size categories—small, medium, and large—each optimized for different languages and dependencies. Select by project type and language requirements to balance speed and compatibility. Larger images include more tools but consume more disk space and memory.

Configure memory, CPU limits, and volume mounts in .actrc or per-workflow settings. Mount Docker sockets for container-in-container tasks, bind local directories as volumes, and set resource constraints to match your development machine. These settings optimize performance and enable integration testing.

Yes. Act supports Docker socket mounting and network configuration, enabling workflows that build, push, or run containers. Configure the Docker socket in your act setup to allow nested container operations within the act runner environment.

Slow workflows often stem from oversized runner images, memory constraints, or I/O bottlenecks. Troubleshoot by switching to smaller images, increasing allocated memory and CPU, checking volume mount performance, and monitoring container lifecycle. Act provides configuration options to diagnose and resolve these issues.

No. Act runs standard GitHub Actions workflow YAML without modification. Your workflows execute identically in act and on GitHub's servers, so local testing produces reliable results that match production behavior.