Contrary to what is possible in Docker Swarm, you cannot run containers directly in a Kubernetes cluster. In a Kubernetes cluster, you can only run pods. Pods are the atomic units of deployment in Kubernetes. A pod is an abstraction of one or many co-located containers that share the same Kernel namespaces, such as the network namespace. No equivalent exists in Docker SwarmKit. The fact that more than one container can be co-located and share the same network namespace is a very powerful concept. The following diagram illustrates two pods:
In the preceding diagram, we have two pods, Pod 1 and Pod 2. The first pod contains two containers, while the second one only contains a single container. Each pod gets an IP address assigned by Kubernetes that is unique in the whole Kubernetes cluster. In our case, these are the...
