What Is a Pull-Through Cache?

A pull-through cache is a registry mode that proxies requests to an upstream registry, caching each image the first time it is pulled and serving subsequent pulls from the local copy. Unlike a fully replicated mirror, it only stores what has actually been requested. It transparently reduces repeat pulls of the same image.

Why it matters

In CI, where many jobs pull the same base images, a pull-through cache eliminates redundant downloads and dodges upstream rate limits. Latchkey managed runners can pair this with their dependency and Docker layer caching to cut build setup time.

Related guides