CI Runner does not wait for Docker to start before using Docker executor
When the runner is configured to use the Docker executor, builds can fail if Docker is not running. When the runner's host boots, a race condition occurs between Docker and the CI runner if there are pending builds. If docker is unable to complete it's startup before the CI runner picks up a build, the build will fail with something like
gitlab-ci-multi-runner 0.7.2 (998cf5d) Using Docker executor with image ubuntu:14.04 ... Pulling docker image mysql:5.5 ... WARNING: Cannot pull the latest version of image mysql:5.5 : unexpected EOF WARNING: Locally found image will be used instead. Starting service mysql:5.5 ... ERROR: Build failed with: Post http://unix.sock/v1.18/containers/create?name=runner-841666bc-project-11111-concurrent-0-mysql: dial unix /var/run/docker.sock: no such file or directory
The fix for this should be that the runner will not begin a build if the Docker daemon is not running.