What Is a Docker Action?

A Docker action is an action whose logic runs inside a container image built from a Dockerfile or pulled from a registry. The image carries its own dependencies, so the action runs the same regardless of what is installed on the runner. It trades startup cost for strong isolation and a self-contained environment.

Why it matters

Docker actions let an author ship an exact environment without polluting the runner or relying on preinstalled tools. The cost is image pull and container startup time, and a restriction to runner OSes that support the container. They suit actions with heavy or unusual dependencies.

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