Kubernetes - Update Deployment

Step-00: Introduction¶

We can update deployments using two options
Set Image
Edit Deployment

Step-01: Updating Application version V1 to V2 using "Set Image" Option¶

Update Deployment¶

Observation: Please Check the container name in spec.container.name yaml output and make a note of it and replace in kubectl set image command

# Get Container Name from current deployment
kubectl get deployment my-first-deployment -o yaml

# Update Deployment - SHOULD WORK NOW
kubectl set image deployment/<Deployment-Name> <Container-Name>=<Container-Image> 
kubectl set image deployment/my-first-deployment kubenginx=stacksimplify/kubenginx:2.0.0

Verify Rollout Status (Deployment Status)¶

Observation: By default, rollout happens in a rolling update model, so no downtime.

# Verify Rollout Status 
kubectl rollout status deployment/my-first-deployment

# Verify Deployment
kubectl get deploy

Describe Deployment¶

Observation:
Verify the Events and understand that Kubernetes by default do "Rolling Update" for new application releases.

With that said, we will not have downtime for our application.

# Descibe Deployment
kubectl describe deployment my-first-deployment

Verify ReplicaSet¶

Observation: New ReplicaSet will be created for new version
```
# Verify ReplicaSet
kubectl get rs
```

Verify Pods¶

Observation: Pod template hash label of new replicaset should be present for PODs letting us know these pods belong to new ReplicaSet.
```
# List Pods
kubectl get po
```

Access the Application using Public IP¶

We should see Application Version:V2 whenever we access the application in browser

# Get Load Balancer IP
kubectl get svc

# Application URL
http://<External-IP-from-get-service-output>

Update Change-Cause for the Kubernetes Deployment - Rollout History¶

Observation: We have the rollout history, so we can switch back to older revisions using revision history available to us.

# Verify Rollout History
kubectl rollout history deployment/my-first-deployment

# Update REVISION CHANGE-CAUSE
kubectl annotate deployment/my-first-deployment kubernetes.io/change-cause="Deployment UPDATE - App Version 2.0.0 - SET IMAGE OPTION"

# Verify Rollout History
kubectl rollout history deployment/my-first-deployment

Step-02: Update the Application from V2 to V3 using "Edit Deployment" Option¶

Edit Deployment¶

# Edit Deployment
kubectl edit deployment/<Deployment-Name> 
kubectl edit deployment/my-first-deployment

# Change From 2.0.0
    spec:
      containers:
      - image: stacksimplify/kubenginx:2.0.0

# Change To 3.0.0
    spec:
      containers:
      - image: stacksimplify/kubenginx:3.0.0

Verify Rollout Status¶

Observation: Rollout happens in a rolling update model, so no downtime.

# Verify Rollout Status 
kubectl rollout status deployment/my-first-deployment

# Describe Deployment
kubectl describe deployment/my-first-deployment

Verify Replicasets¶

Observation: We should see 3 ReplicaSets now, as we have updated our application to 3rd version 3.0.0
```
# Verify ReplicaSet and Pods
kubectl get rs
kubectl get po
```

Access the Application using Public IP¶

We should see Application Version:V3 whenever we access the application in browser

# Get Load Balancer IP
kubectl get svc

# Application URL
http://<External-IP-from-get-service-output>

Update Change-Cause for the Kubernetes Deployment - Rollout History¶

Observation: We have the rollout history, so we can switch back to older revisions using revision history available to us.

# Verify Rollout History
kubectl rollout history deployment/my-first-deployment

# Update REVISION CHANGE-CAUSE
kubectl annotate deployment/my-first-deployment kubernetes.io/change-cause="Deployment UPDATE - App Version 3.0.0 - EDIT DEPLOYMENT OPTION"

# Verify Rollout History
kubectl rollout history deployment/my-first-deployment