Rolling Updates And Rolling Back Deployments in Kubernetes

Task:
There is a production deployment planned for next week. The Nautilus DevOps team wants to test the deployment update and rollback on Dev environment first so that they can identify the risks in advance. Below you can find more details about the plan they want to execute.

Create a namespace devops. Create a deployment called httpd-deploy under this new namespace, It should have one container called httpd, use httpd:2.4.27 image and 6 replicas. The deployment should use RollingUpdate strategy with maxSurge=1, and maxUnavailable=2.
Next upgrade the deployment to version httpd:2.4.43 using a rolling update.
Finally, once all pods are updated undo the update and roll back to the previous/original version.
Note: The kubectl utility on jump_host has been configured to work with the kubernetes cluster.

Step 1) Create a Name Space

thor@jump_host /$ kubectl create namespace devops

namespace/devops created

Step 2)  Create a deployment called httpd-deploy under this new namespace, It should have one container called httpd, use httpd:2.4.27 image and 6 replicas. The deployment should use RollingUpdate strategy with maxSurge=1, and maxUnavailable=2.

thor@jump_host ~$ cat deploy.yaml 

apiVersion: apps/v1

kind: Deployment

metadata:

  name: httpd-deploy

  namespace: devops

spec:

  replicas: 6

  strategy:

    type: RollingUpdate

    rollingUpdate:

      maxSurge: 1

      maxUnavailable: 2

  selector:

    matchLabels:

      app: devops

  template:

    metadata:

      labels:

        app: devops

    spec:

      containers:

      - image: httpd:2.4.27

        name: httpd

Step 3) Apply the changes

thor@jump_host ~$ kubectl apply -f deploy.yaml 

deployment.apps/httpd-deploy created

Step 4) Validate the deployment version 

thor@jump_host ~$ kubectl get deployments --namespace=devops  -o wide

NAMESPACE     NAME           READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES                     SELECTOR

devops        httpd-deploy   6/6     6            6           23s   httpd        httpd:2.4.27               app=devops

Step 5) Check the deployment Revision

kubectl rollout history deployment/httpd-deploy --namespace=devops

deployment.apps/httpd-deploy 

REVISION  CHANGE-CAUSE

1         <none>

Step 6) Upgrade the deployment to version httpd:2.4.43 using a rolling update.

thor@jump_host ~$ kubectl set image deployment/httpd-deploy httpd=httpd:2.4.43 --namespace=devops --record=true

deployment.apps/httpd-deploy image updated

Step 7) Validate the deployment 

thor@jump_host ~$ kubectl get deployments --namespace=devops  -o wide

NAME           READY   UP-TO-DATE   AVAILABLE   AGE    CONTAINERS   IMAGES         SELECTOR

httpd-deploy   6/6     6            6           114s   httpd        httpd:2.4.43   app=devops

Step 8) Undo the update and roll back to the previous/original version

thor@jump_host ~$ kubectl rollout undo deployment/httpd-deploy --to-revision=1 --namespace=devops

deployment.apps/httpd-deploy rolled back

Step 9) Validate the deployment version 

thor@jump_host ~$ kubectl get deployments --namespace=devops  -o wide

NAME           READY   UP-TO-DATE   AVAILABLE   AGE     CONTAINERS   IMAGES         SELECTOR

httpd-deploy   6/6     6            6           2m53s   httpd        httpd:2.4.27   app=devops