Jarle Aase

How to share a private docker image or container securely

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Some times it's required to copy a docker container between machines, or even developers. One option is to use a hosted repository and pay some money for this opportunity. Another option is to use a machine that has a reachable IP address and Docker to run a private and secure Docker Registry.

In this example we have a Linux VM somewhere on the network or Internet. That VM will accept ssh connections from us.

First we set up a ssh forwarding tunnel.

$ ssh -L 5000:localhost:5000 YOUR_VMS_IP_HERE

Run a Docker Registry container in your VM.

From a shell in your VM, run:

$ docker run -d -p 5000:5000 --restart=always --name registry registry

If we want to share a container with state, stop it and commit it. Lets say we want the image to have the name Dolly.

Back in a shell on your local machine, run:

$ docker commit DOCKER_IMAGE_ID_OR_NAME localhost:5000/Dolly

Alternatively, if we want to share a local image:

$ docker tag Dolly localhost:5000/Dolly

Then finally, push the image to the VM.

$ docker push localhost:5000/Dolly

Now you can set up a tunnel from your other machine (or the other developer(s) can do that) and just pull it or run it.

$ docker run localhost:5000/Dolly

And that's it.