Containers and pods

Let’s clear up some terminology before getting into the detail.

We sometimes use the terms container and pod to mean the same thing. However, a pod is actually a thin wrapper around one or more containers and is a mandatory requirement for any container that wants to run on Kubernetes. This means containers must be wrapped in a pod if they want to run on Kubernetes. The following extremely simple YAML file defines a pod with a single container.

1  apiVersion: v1
2  kind: Pod
3  metadata:
4    name: kcna-pod
5    labels:
6      project: kcna-book
7  spec:
8    containers:     <<==== Container is defined below here
9      - name: kcna-container
10       image: <container-image-goes-here>

Lines 1-7 give the pod and name and a label. Lines 8-10 show the container definition embedded within the overall pod definition. As the container is embedded within the pod definition, we say the pod “wraps the container”.

As well as...