Docker Build Cache Invalidation Limits for Remote Resource Updates

Docker utilizes a content-addressable storage system where layers are cached based on the instruction string and the state of the parent layer. This mechanism ensures efficiency during iterative builds by skipping unchanged steps.

A limitation arises when using RUN instructions to fetch external dependencies, such as apt-get update or curl commands. Because Docker evaluates the command string rather than the remote state of the resource, the build engine may report a cache hit even if the remote repository has been updated with new packages or security patches.

When relying on BuildKit for image construction, there is uncertainty regarding the most efficient way to trigger a refresh of these volatile layers without resorting to a global --no-cache flag, which invalidates the entire build pipeline.

• What are the documented methods for selectively invalidating a specific RUN layer based on external changes?
• How can build arguments be utilized to force a cache miss for a single stage in a multi-stage build?