To understand the Docker container backup and recovery process we first need to understand the difference between docker image and docker container. A docker image contains an operating system with possibly one or more prefigured applications. Whereas, a docker container is a running instance created from an image.
Docker container backupWhen we need make a backup of a docker container we
commitits current state and save it as a docker image.
# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 78727078a04b debian:8 "/bin/bash" 13 seconds ago Up 11 seconds container1From the above output we see a running docker container named
container1with an ID
78727078a04b. We now use
commitcommand to take a snapshot of its current running state:
# docker commit -p 78727078a04b container1 e09f9ac65c8b3095927c14ca0594868f73831bde0800ce66415afeb91aea93cfWith do above command we have first paused a running container with
-poption, made a commit to save the entire snapshot as a docker image with a name
# docker images REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE container1 latest e09f9ac65c8b 39 seconds ago 125.1 MB
Now we have a container backup saved as an image waiting to be redeployed again. If we wish to redeploy our
container1image on another docker host system we may
pushthe image to some private docker repository:
# docker login # docker push container1or we can save it as a tar file and move it freely to any desired docker host system for a deployment:
# docker save -o ~/container1.tar container1 [root@localhost lubos]# ls -l ~/container1.tar -rw-r--r--. 1 root root 131017216 Jun 14 20:31 /root/container1.tar
Docker container recoveryThe above paragraphs explained how to backup a docker container. In this section we will discuss how recover from a docker backup.
In case that we have pushed our backed up docker container image to a private repository we can simply use docker
runcommand to start a new instance from the
container1image. If we have transferred our
container1.tarbackup file to another docker host system we first need to
loadbacked up tar file into a docker's local image repository:
# docker load -i /root/container1.tarConfirm that the image was loaded with:
# docker imagesNow we can use docker
runcommand to start a new instance from the above loaded