Rolling Update of an NGINX Deployment on Kubernetes
This article documents the process of performing a rolling update on a Kubernetes deployment to update the NGINX web server to version 1.18. The deployment, named nginx-deployment, was updated to reflect recent changes from the application development team.
1. Initiating the Rolling Update
To start the rolling update, the kubectl set image command was used. This command tells Kubernetes to update the nginx-container within the nginx-deployment to use the new nginx:1.18 image. Kubernetes then begins the rolling update process, which creates new pods with the updated image while gracefully terminating the old ones, ensuring the application remains available.
thor@jumphost ~$ kubectl set image deployment/nginx-deployment nginx-container=nginx:1.18
deployment.apps/nginx-deployment image updated
2. Verifying the Rollout Status
After initiating the update, the kubectl rollout status command was used to monitor the progress. The command confirms that the new pods have been successfully created and are ready to serve traffic.
thor@jumphost ~$ kubectl rollout status deployment/nginx-deployment
deployment "nginx-deployment" successfully rolled out
3. Checking for Pods in the Correct Namespace
Initially, a check for pods using the label app=nginx failed to show any resources. This is because the deployment's pods were located in the default namespace, while the initial command may have been looking in a different or unspecified namespace. To resolve this, kubectl get pods was run with the --all-namespaces flag. This command correctly located the pods and showed them running in the default namespace.
thor@jumphost ~$ kubectl get pods -l app=nginx
No resources found in default namespace.
thor@jumphost ~$ kubectl get pods --all-namespaces
NAMESPACE NAME READY STATUS RESTARTS AGE
default nginx-deployment-58cf54c7f6-hzwvn 1/1 Running 0 2m43s
default nginx-deployment-58cf54c7f6-w4wh4 1/1 Running 0 2m51s
default nginx-deployment-58cf54c7f6-wznkx 1/1 Running 0 2m41s
kube-system coredns-5d78c9869d-bn6v4 1/1 Running 0 13m
kube-system coredns-5d78c9869d-g75tz 1/1 Running 0 13m
kube-system etcd-kodekloud-control-plane 1/1 Running 0 13m
kube-system kindnet-grrg5 1/1 Running 0 13m
kube-system kube-apiserver-kodekloud-control-plane 1/1 Running 0 13m
kube-system kube-controller-manager-kodekloud-control-plane 1/1 Running 0 13m
kube-system kube-proxy-jtxjl 1/1 Running 0 13m
kube-system kube-scheduler-kodekloud-control-plane 1/1 Running 0 13m
local-path-storage local-path-provisioner-6bc4bddd6b-54lws 1/1 Running 0 13m
4. Final Verification
The last step was to confirm that the new pods were indeed using the correct nginx:1.18 image. This was done by using the kubectl describe pod command on one of the new pods, nginx-deployment-58cf54c7f6-hzwvn. The output clearly showed that the nginx-container's image had been updated to the desired version.
thor@jumphost ~$ kubectl describe pod nginx-deployment-58cf54c7f6-hzwvn
Name: nginx-deployment-58cf54c7f6-hzwvn
Namespace: default
Priority: 0
Service Account: default
Node: kodekloud-control-plane/172.17.0.2
Start Time: Tue, 23 Sep 2025 05:17:44 +0000
Labels: app=nginx-app
pod-template-hash=58cf54c7f6
Annotations: <none>
Status: Running
IP: 10.244.0.9
IPs:
IP: 10.244.0.9
Controlled By: ReplicaSet/nginx-deployment-58cf54c7f6
Containers:
nginx-container:
Container ID: containerd://df902a1d0ebdef8caad17cab31cddec1af4a4c5f6152b0933e6e460c8b7a9fbd
Image: nginx:1.18
Image ID: docker.io/library/nginx@sha256:e90ac5331fe095cea01b121a3627174b2e33e06e83720e9a934c7b8ccc9c55a0
Port: <none>
Host Port: <none>
State: Running
Started: Tue, 23 Sep 2025 05:17:45 +0000
Ready: True
Restart Count: 0
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-smr26 (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
kube-api-access-smr26:
Type: Projected (a volume that contains injected data from multiple sources)
TokenExpirationSeconds: 3607
ConfigMapName: kube-root-ca.crt
ConfigMapOptional: <nil>
DownwardAPI: true
QoS Class: BestEffort
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 7m41s default-scheduler Successfully assigned default/nginx-deployment-58cf54c7f6-hzwvn to kodekloud-control-plane
Normal Pulled 7m41s kubelet Container image "nginx:1.18" already present on machine
Normal Created 7m41s kubelet Created container nginx-container
Normal Started 7m40s kubelet Started container nginx-container
The output confirms the successful update and shows that the new pods are running and healthy. This completes the rolling update process for the NGINX application.
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