[Backup Docker] Saving Images and Containers as Tar Files for Sharing
Saving Images and Containers as Tar Files for Sharing
Imagine a scenario where you have built Docker images and containers that you would be interested to keep and share it with your other collaborators or colleagues. The below methods shall help you achieve it.
Four basic Docker CLI comes into action:
- The
docker export
- Export a container's filesystem as a tar archive - The
docker import
- Import the contents from a tarball to create a filesystem image - The
docker save
- Save one or more images to a tar archive (streamed to STDOUT by default) - The
docker load
- Load an image from a tar archive or STDIN
Tested Infrastructure
| Platform | Number of Instance | Reading Time |
| Play with Docker | 1 | 5 min |
Pre-requisite
- Create an account with DockerHub
- Open PWD Platform on your browser
- Click on Add New Instance on the left side of the screen to bring up Alpine OS instance on the right side
Create Nginx Container
$ docker run -d -p 80:80 nginx
Unable to find image 'nginx:latest' locally
latest: Pulling from library/nginx
a5a6f2f73cd8: Pull complete
1ba02017c4b2: Pull complete
33b176c904de: Pull complete
Digest: sha256:5d32f60db294b5deb55d078cd4feb410ad88e6fe77500c87d3970eca97f54dba
Status: Downloaded newer image for nginx:latest
df2caf9283e84a15bb2321a17aabe84e3e0762ec82fc180e2a4c15fcf0f96588
[node1] (local) [email protected] ~
Displaying Running Container
$ docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
df2caf9283e8 nginx "nginx -g 'daemon of..." 35 seconds ago Up 34 seconds 0.0.0.0:80->80/tcp vigorous_jang
$ docker export df2 > nginx.tar
You could commit this container as a new image locally, but you could also use the Docker import command:
$ docker import - mynginx < nginx.tar
sha256:aaaed50d250a671042e8dc383c6e05012e245f5eaf555d10c40be63f6028ee7b
$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
mynginx latest aaaed50d250a 25 seconds ago 107MB
nginx latest 568c4670fa80 2 weeks ago 109MB
If you wanted to share this image with one of your collaborators, you could upload the tar file on a web server and let your collaborator download it and use the import command on his Docker host.
If you would rather deal with images that you have already committed, you can use the load and save commands:
$ docker save -o mynginx1.tar nginx
$ ls -l
total 218756
-rw------- 1 root root 112844800 Dec 18 02:53 mynginx1.tar
-rw-r--r-- 1 root root 111158784 Dec 18 02:50 nginx.tar
$ docker rmi mynginx
Untagged: mynginx:latest
Deleted: sha256:aaaed50d250a671042e8dc383c6e05012e245f5eaf555d10c40be63f6028ee7b
Deleted: sha256:41135ad184eaac0f5c4f46e4768555738303d30ab161a7431d28a5ccf1778a0f
Now delete all images and containers running and try to run the below command to load Docker image into your system:
$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
$ docker load < mynginx1.tar
Loaded image: nginx:latest
[node1] (local) [email protected] ~$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
nginx latest 568c4670fa80 2 weeks ago 109MB
[node1] (local) [email protected] ~
$