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Balkrishna Pandey
Balkrishna Pandey

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How to update a Kubernetes deployment?

#kubernetes #cka

Let's say you want to use the nginx:1.13 image instead of the nginx:latest image. You can update deployment using the following command:


kubectl set image deployments nginx nginx=nginx:1.13
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Verify it using the kubectl get pods -l app=frontend command. You will see some of the pods are in the Terminating state and some of them are in the ContainerCreating state.


kubectl get pods -l app=frontend

NAME           READY  STATUS       RESTARTS  AGE

nginx-54fd96d656-pkhc4  0/1   ContainerCreating  0     1s

nginx-54fd96d656-vgj7f  1/1   Running       0     9s

nginx-776567f984-sdrns  1/1   Running       0     11m

nginx-776567f984-vxdzw  1/1   Terminating     0     11m
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Sometimes later you will all the pods are updated,


kubectl get pods -l app=frontend
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Output:


NAME           READY  STATUS  RESTARTS  AGE

nginx-54fd96d656-pkhc4  1/1   Running  0     118s

nginx-54fd96d656-vgj7f  1/1   Running  0     2m6s
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Let's confirm the image version as follows,


kubectl describe po nginx-54fd96d656-pkhc4 | grep -i image
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You can see image version is nginx:1.13.


  Image:     nginx:1.13

  Image ID:    docker-pullable://nginx@sha256:b1d09e9718890e6ebbbd2bc319ef1611559e30ce1b6f56b2e3b479d9da51dc35

 Normal Pulling  92s  kubelet      Pulling image "nginx:1.13"

 Normal Pulled   91s  kubelet      Successfully pulled image "nginx:1.13" in 852.963655ms
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You can also update the nginx deployment using yaml file. In yaml file update your image: nginx:latest section with image: 1.13 and use the following command:


kubectl apply -f nginx-deployment.yaml
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This will update the deployment based on the changes you made in the nginx-deployment.yaml file.

How to rollback a deployment update?

You can rollback a deployment update using the following command:


kubectl rollout undo deployments nginx
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Output:


deployment.apps/nginx rolled back
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Now, you should see all the pods are running with nginx:latest image.


kubectl get pods -l app=frontend
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Output:


NAME           READY  STATUS       RESTARTS  AGE

nginx-54fd96d656-pkhc4  1/1   Running       0     5m5s

nginx-54fd96d656-vgj7f  1/1   Terminating     0     5m13s

nginx-776567f984-nkp9z  1/1   Running       0     2s

nginx-776567f984-w9bsl  0/1   ContainerCreating  0     0s
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Lets verify the image,


kubectl describe po nginx-776567f984-nkp9z | grep -i image
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Output:


  Image:     nginx:latest

  Image ID:    docker-pullable://nginx@sha256:2bcabc23b45489fb0885d69a06ba1d648aeda973fae7bb981bafbb884165e514

 Normal Pulling  94s  kubelet      Pulling image "nginx:latest"

 Normal Pulled   94s  kubelet      Successfully pulled image "nginx:latest" in 829.083943ms
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