Caching multi-stage Docker builds in Cloud Build
Shows how to fix caching multi-stage Docker builds in Cloud Build. Use it when you hit this exact problem. Skip it when your error message or symptom looks different.
TL;DR
Context: Stack Overflow #52646303 (top answer, 61 votes): after switching to multi-stage Docker builds, intermediate layers stop being cached and every build is slow.
Steps
- Build and push each intermediate stage as its own tagged image, then reference all of them in --cache-from. Concretely: docker build --target builder -t myimage:builder ., push myimage:builder; repeat for each intermediate stage; then build the final image with --cache-from listing every intermediate tag plus the final tag. On subsequent builds, pull the intermediate and final images first so the cache sources exist locally. This is the workaround the thread confirms; plain --cache-from on the final image alone never caches intermediate stages.
When to use
You are seeing this: Build and push each intermediate stage as its own tagged image, then reference all of them in --cache-from. Use this skill when you run into "Caching multi-stage Docker builds in Cloud Build".
When not to use
If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.
Versions
No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.
Why this happens
The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.