How to copy Docker images from one host to another without using a repository

Question

How do I transfer a Docker image from one machine to another one without using a repository, no matter private or public?

I create my own image in VirtualBox, and when it is finished I try to deploy to other machines to have real usage.

Since it is based on my own based image (like Red Hat Linux), it cannot be recreated from a Dockerfile. My dockerfile isn't easily portable.

Are there simple commands I can use? Or another solution?

Answer 1

You will need to save the Docker image as a tar file:

docker save -o <path for generated tar file> <image name>

Then copy your image to a new system with regular file transfer tools such as cp, scp or rsync(preferred for big files). After that you will have to load the image into Docker:

docker load -i <path to image tar file>

PS: You may need to sudo all commands.

EDIT: You should add filename (not just directory) with -o, for example:

docker save -o c:/myfile.tar centos:16