Docker

To quickly run with Docker, just use:

$ docker run -d -p 8080:8080 -v `pwd`/gitbucket-data:/gitbucket gitbucket/gitbucket

the Web UI will be reachable under http://localhost:8080/
the GitBucket Data (config, DB, Git repos, plug-ins) will be persisted to ~/gitbucket-data.
to access this Git repository over SSH (port 29418) too, one needs to enable it in the Web UI too: GitBucket > Administration > System Settings > SSH access

Other images

There are several existing Docker images for GitBucket:

Things to consider when creating/using a Docker image:

the GITBUCKET_HOME is usually mapped outside the Docker container (to be able to update without loosing data)
one might want to put a reverse proxy in front of GitBucket, such as Apache Httpd, NginX or Caddy
one can map the SSH port too, if this is desired (needs to be activated from the UI too)
don't forget about GitBucket plug-ins:
- they're mapped outside the container too,
- so when updating the Docker container they need quite often to be updated too.
- download the plug-ins working with latest GitBucket from: https://github.com/gitbucket-plugins/gitbucket-community.herokuapp.com/tree/master/plugins
if an external DB is desired (so not the built in H2), than docker-compose might help.
or use a UI like Portainer in order to manage your Docker.