Build an image from a Dockerfile - and survive the build doing it in CI.
docker build packages a build context and a Dockerfile into an image. In modern Docker it invokes BuildKit by default. This page covers the flags you use most and the build failures that break CI.
What it does
docker build sends a build context (a directory, usually the current one) to the daemon and executes each Dockerfile instruction to produce a layered image. The final argument is the context path, not the Dockerfile path.
--no-cache makes this build ignore every cached layer; it does not delete the cache, so the disk is unchanged and the next build without the flag reuses layers again. Reach for it when a build is producing a stale result you cannot explain - an apt or apk index frozen at whatever a RUN step saw days ago is the usual culprit - and pair it with --pull, which also re-resolves the base image tag. In CI it costs you the whole build every time, so it belongs on a scheduled or manual job rather than on every push.
Terminal
docker build --no-cache --pull -t myapp:ci . # ignore layers AND re-pull the base
docker builder prune -af # actually free the cache from disk
Common errors in CI
A frequent CI failure is "failed to compute cache key: ... not found" - the Dockerfile COPYs a path that is not in the build context (often because of .dockerignore or because CI runs from a different working directory). Fix by running build from the repo root with the correct context, e.g. docker build -f path/to/Dockerfile . , and confirm the file is not excluded by .dockerignore. A second is running out of disk: "no space left on device" mid-build - prune with docker system prune -af or use a larger runner.
Frequently asked questions
docker build: Usage, Options & Common CI Errors?
docker build packages a build context and a Dockerfile into an image. In modern Docker it invokes BuildKit by default. This page covers the flags you use most and the build failures that break CI.
What it does?
docker build sends a build context (a directory, usually the current one) to the daemon and executes each Dockerfile instruction to produce a layered image. The final argument is the context path, not the Dockerfile path.
Building without the cache?
--no-cache makes this build ignore every cached layer; it does not delete the cache, so the disk is unchanged and the next build without the flag reuses layers again. Reach for it when a build is producing a stale result you cannot explain - an apt or apk index frozen at whatever a RUN step saw days ago is the usual culprit - and pair it
Common errors in CI?
A frequent CI failure is "failed to compute cache key: ... not found" - the Dockerfile COPYs a path that is not in the build context (often because of .dockerignore or because CI runs from a different working directory). Fix by running build from the repo root with the correct context, e.g. docker build -f path/to/Dockerfile .
