This image assumes you mount a host directory with an already checked out Git repository. It will determine whether or not there are any remote changes that need to be pulled down. The exit code of the container will be 0 when there are no changes and 1 when there are changes.
See for an example on how to use this container below:
Mount a host directory and issue the gitpoll
docker run -v $PWD:/mnt -i manorrock/gitpoll:2.12.0 gitpoll
Note the default work directory of this container is /mnt