Lab 3: Publishing a container

Docker registry

The container is now running on mesos-agent01, but what if we want to have it run on server02? It is possible to manually export/import the image from one host to another, but it is more practical to use a Docker registry.

A Docker registry is an image repository of Docker containers. You can ‘push’ a container into the public Docker Hub or maintain your own private Docker registry/repository. For the lab we have previously created a registry that lives at ‘registry:5000’ (running on mesos-agent01).

Note

We already setup docker to use this registry in the /etc/default/docker file (need to be root to access it)

Docker tag

Currently ‘mycontainer:5.6’ lives locally on server01. We need to apply a tag that will indicate where we want it to go, then me need to push/copy the image to that location.

Run

docker tag mycontainer:5.6 registry:5000/mycontainer:5.6
docker images

Note

Note that you have two tags with the same Image ID.

Now run:

docker push registry:5000/mycontainer:5.6

Open a terminal window to server02. You have the following shortcut on your desktop, use it.

Run

docker run --rm -p 8080:80 --name myapp mycontainer:5.6

Note that the command failed. The container does not exist on this host. Now run.

docker run --rm -p 8080:80 --name myapp registry:5000/mycontainer:5.6

Note

The option ‘–-rm’ specify that the container should be automatically removed with it exits

The container was found on the private registry and was started. Verify by visiting http://10.1.10.12:8080 in Chrome.

We are done with this container so we can delete it. Since we specified the ‘rm’ option, you just need to terminate the process. You can do so by doing

Ctrl+C

Make sure that it got removed with this command

docker ps -a

You can now close the agent02 terminal window. It will not be used for the rest of the lab.