apk add --no-cache: Usage, Options & Common CI Errors

--no-cache installs Alpine packages while leaving no package index behind in the image.

apk add --no-cache is the canonical one-liner for Alpine Docker images: it fetches a fresh index, installs, and discards the index in a single step - no separate apk update and no cache to clean up.

What it does

Without --no-cache, apk caches the package index under /var/cache/apk, which you then have to delete to keep the image small. --no-cache fetches the index, uses it for this install, and does not write it to disk - equivalent to apk update + install + rm of the cache, but in one atomic step.

Common usage

apk add --no-cache curl                       # the standard idiom
RUN apk add --no-cache python3 py3-pip         # in a Dockerfile
apk add --no-cache --virtual .build gcc musl-dev && apk del .build

Common errors in CI

If you omit --no-cache and forget to clean up, the image carries the /var/cache/apk index for no benefit. The reverse trap: a script that runs apk add (no flag) without a prior apk update on a base whose index is stale fails with "no such package" - --no-cache avoids that because it always pulls a current index. Pinning an exact version under --no-cache can still hit "unsatisfiable constraints" once Alpine prunes that version from the repo.

Options

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