What is the difference between docker save and docker export?

First, let’s explain docker save and docker export respectively:

docker save

docker’s command line interface The design is very elegant, and the help for many commands can be viewed directly by adding --help at the end.

The help of docker save is as follows:

>docker save --help
Usage:  docker save [OPTIONS] IMAGE [IMAGE...]
Save one or more images to a tar archive (streamed to STDOUT by default)
Options:
      --help            Print usage
  -o, --output string   Write to a file, instead of STDOUT

As can be seen from the command line help, docker save is a tool used to package and save one or more images.

For example, if we want to package postgres and mongo in the mirror library, we can execute:

docker save -o images.tar postgres:9.6 mongo:3.4

The packaged images.tar contains the two images of postgres:9.6 and mongo:3.4.

Although the command line parameters require the image to be specified, the container can actually be packaged, for example:

>docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS               NAMES
3623943d369f        postgres:9.6        "docker-entrypoint..."   3 hours ago         Up 3 hours          5432/tcp            postgres
>docker save -o b.tar postgres
>docker save -o c.tar postgres:9.6
>ls -al
-rwxrwxrwx 1 root root 277886464 8月  26 14:40 b.tar
-rwxrwxrwx 1 root root 277886464 8月  26 14:41 c.tar

As you can see from the above command, b.tar and c.tar are exactly the same . This shows that if docker save specifies a container, docker save will save the image behind the container.

Load the packaged image using docker load, for example:

docker load -i images.tar

The above command will load postgres:9.6 and mongo:3.4. If the local image library These two images already exist and will be overwritten.

The application scenario of docker save is if your application is a combination of multiple images arranged using docker-compose.yml, but the client server you want to deploy cannot connect to the external network. At this time, you can use docker save to package the used image, and then copy it to the client server and use docker load to load it.

docker export

As usual, check the help of docker export:

>docker export --help
Usage:  docker export [OPTIONS] CONTAINER
Export a container's filesystem as a tar archive
Options:
      --help            Print usage
  -o, --output string   Write to a file, instead of STDOUT

As can be seen from the help, docker export is used to convert container files The system is packaged. For example:

docker export -o postgres-export.tar postgres

docker export needs to specify the container, and cannot specify image or container like docker save.

Load the packaged container using docker import, for example:

docker import postgres-export.tar postgres:latest

As can be seen from the above command, docker import will become an image after importing the container, not Restore to a container.

Another point is that docker import can specify IMAGE[:TAG], which means we can specify a new name for the image. If an image with the same name already exists in the local image library, the name of the original image will be stripped and assigned to the new image. The original image will become a ghost and can only be operated through IMAGE ID.

The application scenario of docker export is mainly used to make a basic image. For example, you start a container from an ubuntu image, then install some software and make some settings, and then use docker export to save it as a basic image. Then, distribute this image to others for use, such as as a basic development environment.

The difference between docker save and docker export

• docker save saves the image (image), and docker export saves the container (container) ;

• docker load is used to load the image package, and docker import is used to load the container package, but both will be restored to the image;

• docker load cannot rename the loaded image, but docker import can specify a new name for the image.

Recommended tutorial: docker

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