docker login Command Reference
Authenticate the Docker CLI to a registry.
docker login stores credentials for a registry so subsequent pull and push commands are authorized. The registry argument defaults to Docker Hub; pass a host for any other registry. In CI, feed the secret over stdin rather than as a -p argument.
Common flags
-u, --username- registry username-p, --password- password (avoid in CI; visible in process list)--password-stdin- read the password from stdin (safe for CI)- Positional registry host, e.g. ghcr.io (omit for Docker Hub)
Example
shell
echo "${{ secrets.DOCKERHUB_TOKEN }}" | docker login -u "${{ secrets.DOCKERHUB_USER }}" --password-stdin
echo "${{ secrets.GITHUB_TOKEN }}" | docker login ghcr.io -u "${{ github.actor }}" --password-stdinIn CI
Always use --password-stdin. Passing -p PASSWORD puts the secret in the process argument list and can leak into logs or ps output; the CLI warns about exactly this. Pipe the token in with echo or printf so it never appears as an argument.
Key takeaways
- --password-stdin keeps the secret out of the process list and shell history.
- The registry host argument is required for anything other than Docker Hub.
- Login is per-registry; authenticate each registry you push to or pull from.
Frequently asked questions
docker login Command Reference?
docker login stores credentials for a registry so subsequent pull and push commands are authorized. The registry argument defaults to Docker Hub; pass a host for any other registry. In CI, feed the secret over stdin rather than as a -p argument.
In CI?
Always use --password-stdin. Passing -p PASSWORD puts the secret in the process argument list and can leak into logs or ps output; the CLI warns about exactly this. Pipe the token in with echo or printf so it never appears as an argument.
Related guides
docker logout Command ReferenceReference for docker logout in CI: remove stored registry credentials at the end of a job so cached auth does
docker push Command ReferenceReference for docker push in CI: publish a tagged image or all tags to a registry, with notes on
docker pull Command ReferenceReference for docker pull in CI: fetch an image or all tags from a registry, pin by digest, and pull for a