TASK_145_Kubernetes_Shared_Volumes.md

---

Start:         2023-07-06 21:33:15 Finished:   2023-07-06 21:51:49

---

• Requirements
• Steps
• Resources

---

TASK 145: Kubernetes Shared Volumes

Requirements

We are working on an application that will be deployed on multiple containers within a pod on Kubernetes cluster. There is a requirement to share a volume among the containers to save some temporary data. The Nautilus DevOps team is developing a similar template to replicate the scenario. Below you can find more details about it.

• Create a pod named volume-share-devops.

• For the first container:

  • use image ubuntu with latest tag only and remember to mention the tag i.e ubuntu:latest,

  • container should be named as volume-container-devops-1, and

  • run a sleep command for it so that it remains in running state.

  • Volume volume-share should be mounted at path /tmp/media.

• For the second container,

  • use image ubuntu with the latest tag only and remember to mention the tag i.e ubuntu:latest,

  • container should be named as volume-container-devops-2, and

  • again run a sleep command for it so that it remains in running state.

  • Volume volume-share should be mounted at path /tmp/cluster.

  • Volume name should be volume-share of type emptyDir.

• After creating the pod:

  • exec into the first container i.e volume-container-devops-1, and

  • just for testing create a file media.txt with any content under the mounted path of first container i.e /tmp/media.

  • The file media.txt should be present under the mounted path /tmp/cluster on the second container volume-container-devops-2 as well, since they are using a shared volume.

Note: The kubectl utility on jump_host has been configured to work with the kubernetes cluster.

---

Steps

Check the existing resources.

thor@jump_host ~$ kubectl get all  

NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   27m  

Create the deploy.yml based on the requirements.

apiVersion: v1
kind: Pod
metadata:
  name: volume-share-devops
  labels:
    name: devops
spec:
  volumes:
    - name: volume-share
      emptyDir: {}
  containers:
    - name: volume-container-devops-1
      image: ubuntu:latest
      command: ["/bin/bash", "-c", "sleep 10000"]
      volumeMounts:
        - name: volume-share
          mountPath: /tmp/media
    - name: volume-container-devops-2
      image: ubuntu:latest
      command: ["/bin/bash", "-c", "sleep 10000"]
      volumeMounts:
        - name: volume-share
          mountPath: /tmp/cluster

Apply. Then verify.

kubectl apply -f .

thor@jump_host ~$ kubectl get all  
NAME                      READY   STATUS    RESTARTS   AGE
pod/volume-share-devops   2/2     Running   0          16s

NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   35m

Use exec to create the specified file inside the first container and verify.

kubectl exec -it volume-share-devops -c volume-container-devops-1  -- touch /tmp/media/media.txt  

thor@jump_host ~$ kubectl exec -it volume-share-devops -c volume-container-devops-1  -- ls -la /tmp/media 

total 8
drwxrwxrwx 2 root root 4096 Jul  6 13:49 .
drwxrwxrwt 1 root root 4096 Jul  6 13:48 ..
-rw-r--r-- 1 root root    0 Jul  6 13:49 media.txt 

Since both containers share the same volume, the same file should also be accesible from the second container.

thor@jump_host ~$ kubectl exec -it volume-share-devops -c volume-container-devops-2  -- ls -la /tmp/cluster/
total 8
drwxrwxrwx 2 root root 4096 Jul  6 13:49 .
drwxrwxrwt 1 root root 4096 Jul  6 13:48 ..
-rw-r--r-- 1 root root    0 Jul  6 13:49 media.txt

---

Resources