If you want to backup your jenkins_home
folder, after you start it with docker:
docker run -p 8080:8080 -p 50000:50000 --name jenkins jenkins/jenkins
Backup the jenkins home folder locally via docker <container name>:<folder path> <out_dir>
docker cp jenkins:/var/jenkins_home ./jenkins_home
Now when you re-run jenkins again, reuse this as a persistent volume:
docker run -v jenkins_home:/var/jenkins_home -p 8080:8080 -p 50000:50000 --name jenkins jenkins/jenkins