12 Container orchestration #

In addition to building and managing images, Podman makes it possible to work with pods. A pod is a group of one or more containers with shared resources, such as the network interface. A pod usually encapsulates an application composed of multiple containers into a single unit.

The podman pod can be used to create, delete, query, and inspect pods. To create a new pod, run the podman pod create command. This creates a pod with a random name. To list the existing pods, use the podman pod list command. To view a list of running pods, run podman ps -a --pod. The output of the command looks as follows (the STATUS and CREATED columns are omitted for brevity):

POD ID        NAME                # OF CONTAINERS   INFRA ID
399a120a09ff  suspicious_curie    1                 e57820093817

Notice that the command assigned a random name to the pod (suspicious_curie in this case). You can use the --name parameter to assign the desired name to a pod.

To examine the pod and its contents, run the podman ps -a --pod command and take a look at the output (the COMMAND, CREATED, STATUS, PORTS, and POD ID columns are omitted for brevity):

CONTAINER ID  IMAGE                 NAMES              PODNAME
e57820093817  k8s.gcr.io/pause:3.2  399a120a09ff-infra suspicious_curie

The created pod has an infra container identified by the k8s.gcr.io name. The purpose of this container is to reserve the namespaces associated with the pod and allow Podman to add other containers to the pod.

Using the podman run --pod command, you can run a container and add it to the desired pod. For example, the command below runs a container based on the suse/sle15 image and adds the container to the suspicious_curie pod:

podman run -d --pod suspicious_curie registry.suse.com/suse/sle15 sleep 1h

The command above adds a container that sleeps for 60 minutes and then exits. Run the podman ps -a --pod command again and you should see that the pod now has two containers.

Containers in a pod can be restarted, stopped, and started without affecting the overall status of the pod. For example, you can stop a container using the sudo podman stop CONTAINER_NAME command.

To stop the pod, use the podman pod stop command:

podman pod stop suspicious_curie