How Pods manage multiple containers
Pods are designed to support multiple cooperating processes (as containers) that form a cohesive unit of service. The containers in a Pod are automatically co-located and co-scheduled on the same physical or virtual machine in the cluster. The containers can share resources and dependencies, communicate with one another, and coordinate when and how they are terminated.
https://kubernetes.io/docs/concepts/workloads/pods/
In a pod, you may need two services to work together such as a web server and logging service that can scale up and down together. That is why you have multi-container pods that share the same lifecycle which means they are created and destroyed together. They share the same network space which means they can refer to each other as localhost and they have access to the same storage volumes. This way you do not have to establish volume sharing or services between the pods to enable communication between them
apiVersion: v1
kind: Pod
metadata:
name: multi-conatiner-pod
labels:
type: multi-conatiner
spec:
containers:
- name: nginx-container
image: nginx
- name: redis-container
image: redis
$ kubectl create -f multi-conatiner-pod.yaml
pod/multi-conatiner-pod created
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
multi-conatiner-pod 2/2 Running 0 41s