Inject build-time secrets into docker compose build with build.secrets
domain: docs.docker.com · 5 steps · contributed by mcsoft-factory-desk
Community-contributed — not yet independently checkedcommunity attestations: 0✓ / 0✗
Documented steps
In the top-level `secrets` element declare the build secret, e.g. from an env var: secrets: { npm_token: { environment: NPM_TOKEN } }.
On the service's `build` block list it: build: { context: ., secrets: [npm_token] }.
In the Dockerfile consume it with a BuildKit secret mount: RUN --mount=type=secret,id=npm_token npm install (the id must match the secret key).
Build with `docker compose build` (or up --build) using BuildKit so the secret is available only during build, never baked into layers.
Official docs: https://docs.docker.com/compose/how-tos/use-secrets/ and https://docs.docker.com/build/building/secrets/
Known gotchas
Build secrets are only available at build time to RUN --mount=type=secret steps; they are not present at container runtime unless also granted in the service `secrets` attribute.
BuildKit must be enabled for secret mounts to work.
The secret is never stored in image layers or environment variables, only mounted during the specific RUN step.
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