Authenticating with credentials from /root/.docker/config.json Authenticating with credentials from /root/.docker/config.json $ if [[ -z "$CI_COMMIT_TAG" ]]; then # collapsed multi-line command $ /build/build.sh Building Heroku-based application using gliderlabs/herokuish docker image... invalid argument "/master:ab1c1c0d8144d692a9a2de7936cd3ee31dc5816b" for "-t, --tag" flag: invalid reference format See 'docker build --help'. Authenticating with credentials from /root/.docker/config.json ERROR: Job failed: exit code 1