How to save entire Docker content into tar file?

Question

I tried to install a Ubuntu machine using the Docker command

docker run -it --name mymachine ubuntu

In that Ubuntu machine, I have installed the following applications

1. Java
2. Unzip
3. SSH

And then I performed Docker commit operation docker commit mymachine copymachine. Now if I run this copy image in a new container means it working perfectly. But in my case, I'm trying to save that image file using the "save" command:

docker save copymachine > MachineInfo.tar

And then forwarding this tar file to my another machine and trying to load this image in that Docker using the following command

docker load MachineInfo.tar updatedmachine

If I try to run this image in a container and trying to access the application installed on the previous machine container.

But none of the applications were been showing in the newly created container.

Answer 1

Inlined with @ halfer comment, You need to perform simple export and import. Please perform the following steps.

1. Start the container

docker run -it --name mymachine ubuntu /bin/bash

2. Update and install the jdk

apt update
apt install default-jre

3. Validate that java is up and accessible

java -version

4. Export the image to tar from another command line. First, do a docker ps and note down the container id of the container in which you have installed java, lets say it is 4719ab149ee2. Export the container into a tar using the command.

docker export 4719ab149ee2  > mymachine.tar

5. Stop the container.

docker stop <container_id>

6. Remove the ubuntu image from your local registry by executing the following commands.

docker images
dokcer image rm <image_id>

7. Now import the image from the tar file using the command.

C:\Users\ameena>docker import - mymachine <  mymachine.tar

8. Now check that image has been imported into your local registry by executing the command.

docker images

9. Now create a container from this image using the command.

docker run -it --name mymachinefromimage mymachine:latest /bin/bash

10. Now check that java is present by using the command.

java --version

Note: Step 5,6,7,8,9 are validation steps.