Pod

The pod is a new concept introduced by Kubernetes. A pod is comprised of a group of related containers that represent a specific application. This is the most basic unit within Kubernetes; you don't have to keep thinking about containers because pods are what you should focus on here.

Let's consider an application called XYZ that stores its information in a database that exposes a REST API that is consumed by its UI, as shown in the following diagram:

The XYZ application with its dependencies

It's obvious that we need three separate services to make this application work. If we were dealing with Docker, we would say that we need three different containers, but from a Kubernetes perspective, all these three containers represent a single pod. This abstraction allows us to manage distributed applications more easily. In order to create a pod definition, you should create a .yaml file describing all the containers that are part of the pod. An example of the XYZ application that we mentioned earlier is described in the following code:

apiVersion: v1
kind: Pod
metadata:
    name: application-xyz
spec:
    containers:
        - name: nginx
          image: nginx
          ports:
            - containerPort: 80 

        - name: database
          image: mysql
          volumeMounts:
            - name: mysql-data
              mountPath: /path

        - name: api
          image: <your-api-image>

Once the file is created, you can execute the pod using the following Kubernetes command:

kubectl create -f <file-name.yaml>