Problem Statement
What are self-hosted runners in GitHub Actions?
Explanation
Self-hosted runners are machines you manage that execute GitHub Actions workflows instead of using GitHub-hosted runners. Self-hosted runners provide control over hardware, software, network configuration, and can access internal resources. Use cases include specialized hardware requirements, proprietary software needs, faster build times with caching, or accessing on-premise resources.
Setup involves installing runner application on your machine (Linux, Windows, macOS), registering with GitHub (organization, repository, or enterprise level), and configuring runner settings. Runners can be added to groups for access control and targeting. Jobs target self-hosted runners using runs-on: self-hosted or custom labels: runs-on: [self-hosted, linux, x64].
Advantages include control over environment (install any tools, custom configurations), access to internal resources (databases, APIs behind firewall), cost savings for heavy usage (no minute charges), persistent caching between builds, and specialized hardware (GPU, high memory). Disadvantages include maintenance overhead (updates, security patches), availability management, and security considerations (runners have access to repository secrets).
Best practices for self-hosted runners: use dedicated machines (don't run on development workstations), implement automatic updates, monitor runner health, use runner groups for access control, consider ephemeral runners (fresh environment per job) for security, and implement proper network security. Understanding self-hosted runners enables optimizing workflow execution for specific organizational needs.
