Docker: How to save images & containers in a tar file and restore them on different machine ?
I. Playing with Docker Images
1. Take backup of an image
$ docker images REPOSITORY TAG IMAGE ID CREATED SIZE mariadb 10.1 5a34bfc8f676 2 weeks ago 375MB phpmyadmin/phpmyadmin latest 15ca549393be 5 weeks ago 166MB php 7.2.1-apache f99d319c7004 12 months ago 377MB ### Save the image $ docker save 15ca549393be > /tmp/phpmyadmin_image.tar ### Checkout the generated tar file $ file /tmp/phpmyadmin_image.tar /tmp/phpmyadmin_image.tar: POSIX tar archive $ ls -l /tmp/phpmyadmin_image.tar -rw-r--r-- 1 saket1447583 wheel 174096384 Jan 15 07:03 /tmp/phpmyadmin_image.tar $ du -sh /tmp/phpmyadmin_image.tar 166M /tmp/phpmyadmin_image.tar $
2. Remove image
$ docker rmi 5a34bfc8f676 15ca549393be f99d319c7004 Error response from daemon: conflict: unable to delete 5a34bfc8f676 (must be forced) - image is being used by stopped container 18d933aeca50 Error response from daemon: conflict: unable to delete 15ca549393be (must be forced) - image is being used by stopped container 82181b391f92 Error response from daemon: conflict: unable to delete f99d319c7004 (must be forced) - image is being used by stopped container 265e1f9c08a0 ### Remove them forcefully $ docker rmi 5a34bfc8f676 15ca549393be f99d319c7004 -f Untagged: mariadb:10.1 Untagged: mariadb@sha256:9a67b8153e9c7a7879011449d44e33a7a1c74c8fa8fd29484c6214c9929eb55e Deleted: sha256:5a34bfc8f676e93f8607e2d17658953655cb4ff7d00ac61b346ab6d29e641545 Untagged: phpmyadmin/phpmyadmin:latest Untagged: phpmyadmin/phpmyadmin@sha256:8811552a9939b920bb436c023d3df17e4d9bdec60eeb74eb84a21ecb7e7ab0a7 Deleted: sha256:15ca549393be8da6be36ef39a4b694226059c3b9d4481df1854f153218767977 Untagged: php:7.2.1-apache Untagged: php@sha256:3753d298b1af5b3975518175f29b611edf3b15b27204c917e8283b27df01c619 Deleted: sha256:f99d319c700441fbca80b85f96e8d6c63061d8c50e8c61e7138d101bcd712ab1 $ $ docker images ls --all REPOSITORY TAG IMAGE ID CREATED SIZE $
3. Restore image on same/different system
$ docker image load < phpmyadmin_image.tar
Loaded image ID: sha256:15ca549393be8da6be36ef39a4b694226059c3b9d4481df1854f153218767977
$ docker images --all
REPOSITORY TAG IMAGE ID CREATED SIZE
15ca549393be 5 weeks ago 166MB
$
Tip: Tagging an image
$ docker images --all
REPOSITORY TAG IMAGE ID CREATED SIZE
15ca549393be 5 weeks ago 166MB
$
$ docker image tag 15ca549393be phpmyadmin:1.7
$ docker images --all
REPOSITORY TAG IMAGE ID CREATED SIZE
phpmyadmin 1.7 15ca549393be 5 weeks ago 166MB
II. Playing with Docker Containers
Containers can also be saved and restored similar to images.
Just have a quick view how to do this.
### Save the container to tar file
$ docker export 265e1f9c08a0 > /tmp/container_php.tar
$ file /tmp/container_php.tar
/tmp/container_php.tar: POSIX tar archive
$ du -sh /tmp/container_php.tar
361M /tmp/container_php.tar
### Remove any existing containers & images
### and restore the saved container as image
$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
$ docker ps --all
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
$ docker import /tmp/container_php.tar
sha256:5622104ad36d16864149d7421bfdf185bba11bfc1776a976687a4ac20fe6da9a
$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
5622104ad36d 37 seconds ago 370M
It is recommended to commit the docker container in order to save the container changes into the image and then we can save/load it later.