Docker and CI/CD · Senior · Question 72 of 75

Why might `COPY . .` invalidate the cache on every CI run even if no code changed?

1The COPY instruction always uses timestamps for hashing
✓Correct answer: Files like .git or build output change and aren't ignored
3CI runners disable the cache for COPY instructions

Explanation

BuildKit hashes file contents and metadata in the context. A missing .dockerignore entry for .git, coverage or dist busts the layer each time.

Further reading

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