Docker and CI/CD · Middle · Question 48 of 75

Why are Docker builds on fresh CI runners often slow, and what helps?

✓Correct answer: There's no local cache; export it with --cache-to and reuse it
2CI runners don't support BuildKit, so builds use the old engine
3Images are always rebuilt from scratch by docker push

Explanation

Each job starts on a clean machine. Cache backends (registry, type=gha) store layers between runs so unchanged steps are reused.

Further reading

Test yourself

Take the Docker and CI/CD · Middle quiz: questions and options are shuffled, and you get a review of your mistakes at the end.