Kubernetes - Pod
A pod is a collection of containers and its storage inside a node of a Kubernetes cluster. It is possible to create a pod with multiple containers inside it. For example, keeping a database container and data container in the same pod.
Types of Pod
There are two types of Pods −
- Single container pod
- Multi container pod
Single Container Pod
They can be simply created with the kubctl run command, where you have a defined image on the Docker registry which we will pull while creating a pod.
$ kubectl run <name of pod> --image=<name of the image from registry>
Example − We will create a pod with a tomcat image which is available on the Docker hub.
$ kubectl run tomcat --image = tomcat:8.0
This can also be done by creating the yaml file and then running the kubectl create command.
apiVersion: v1 kind: Pod metadata: name: Tomcat spec: containers: - name: Tomcat image: tomcat: 8.0 ports: containerPort: 7500 imagePullPolicy: Always
Once the above yaml file is created, we will save the file with the name of tomcat.yml and run the create command to run the document.
$ kubectl create –f tomcat.yml
It will create a pod with the name of tomcat. We can use the describe command along with kubectl to describe the pod.
Multi Container Pod
Multi container pods are created using yaml mail with the definition of the containers.
apiVersion: v1 kind: Pod metadata: name: Tomcat spec: containers: - name: Tomcat image: tomcat: 8.0 ports: containerPort: 7500 imagePullPolicy: Always -name: Database Image: mongoDB Ports: containerPort: 7501 imagePullPolicy: Always
In the above code, we have created one pod with two containers inside it, one for tomcat and the other for MongoDB.