ExtractDockerVersion takes a Docker version string in the format: 'Docker version 1.0.0, build abcdef0', extracts the major, minor and patch versions and returns these as a tuple.

IsDockerPresent tests for the presence of Docker by invoking DockerVersion to get the version of Docker if available, and then attempting to parse the version with ExtractDocker version.

IsDockerRunning tests whether Docker is running by invoking DockerInfo which will only return information if Docker is up.

RunAnonymousContainer shells out the command: 'docker run --rm {{extraDockerArgs}} -t {{image}} {{entrypointArgs}}'.

DockerInfo shells out the command 'docker -info', returning the information if the command is successful and panicking if not.

DockerPull shells out the command 'docker pull {{image}}' where image is the name of a Docker image to retrieve from the remote Docker repository.

DockerVersion shells out the command 'docker -v', returning the version information if the command is successful, and panicking if not.