itsthenetwork/alpine-postgres-client repository overview

The entrypoint is /usr/bin/psql.

/usr/bin has other tools, use docker run -it --rm --entrypoint bash itsthenetwork/alpine-postgres-client to run the container interactively and use them instead.

If you are doing dumps or restores, map a volume: docker run -it --rm -v /tmp:/tmp --entrypoint bash itsthenetwork/alpine-postgres-client.