Overview
A significant percentage of GitHub Actions workflows use service containers to run databases, caches, and other dependencies alongside their jobs. Every time a workflow runs, these containers must be pulled from a registry and extracted before the job can begin. This adds seconds to minutes of overhead to every CI run. With Docker container caching, Blacksmith pre-hydrates commonly used containers directly onto the runners. When your workflow starts, the containers are already present and ready to go. The pull and extraction steps become a no-op, shaving valuable time off every job in your repository.Impact
The “Initialize Containers” step in GitHub Actions is where service containers are pulled and started. With Docker container caching, this step goes from taking over a minute to completing in about a second. Before: 1m 20s to initialize containers
How it works
Docker container caching uses sticky disks to persist container images across workflow runs. When a container is first pulled and extracted, it gets stored on a sticky disk associated with your repository. On subsequent runs, the container is already present on the runner and ready to start immediately.Availability
Docker container caching is currently in private beta. To enable this feature for your organization, please reach out to [email protected].Monitoring usage
You can monitor the storage usage for your Docker container sticky disk in the Sticky Disks page in the Blacksmith dashboard. Future updates will add more detailed information about exactly which container images are being cached.Pricing
Docker container caching is powered by sticky disks and is charged at the same rate of $0.50/GB/mo. For pricing details, please visit our pricing page.FAQ
What is the eviction policy?
What is the eviction policy?
Docker container caches are stored on a single sticky disk at the organization level and is automatically evicted after 7 days of inactivity. Each time a workflow uses a cached container, the “last used” timestamp is updated. As long as your workflows use the cached containers at least once within a 7-day window, they will remain available.