Simple dockerfile to host your own gitblit instance with Docker.
docker build -t gitblit .
docker run --rm -it --name gitblit -v /path/to/my/repos:/git -p 10080:8080 gitblit
Now you can open your gitblit instance at http://localhost:10080.
The gitblit instance is meant as a plain viewer for your repositories. It also does not update your repositories, so you have to keep an external script updating all repositories in the mounted directory.