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‎kubernetes/10.md‎

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# Resolve Pod Deployment Issue
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A junior DevOps team member encountered difficulties deploying a stack on the Kubernetes cluster. The pod fails to start, presenting errors. Let's troubleshoot and rectify the issue promptly.
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- There is a pod named `webserver`, and the container within it is named `nginx-container`, its utilizing the `nginx:latest` image.
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- Additionally, there's a sidecar container named `sidecar-container` using the ubuntu:latest image.
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- Identify and address the issue to ensure the pod is in the `running` state and the application is accessible.
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> Note: The kubectl utility on jump_host is configured to interact with the Kubernetes cluster.
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## Steps
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1. Let's get the status of pods
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```sh
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kubectl get pod webserver
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```
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```shell
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kubectl get pod webserver
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NAME READY STATUS RESTARTS AGE
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webserver 1/2 ImagePullBackOff 0 10m
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```
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> we can see there is a problem with container image pulling
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2. Let's see in details
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```sh
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kubectl describe pod webserver
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```
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> We can see events details at the end:
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```shell
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Events:
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Type Reason Age From Message
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---- ------ ---- ---- -------
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Normal Scheduled 13m default-scheduler Successfully assigned default/webserver to kodekloud-control-plane
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Normal Pulling 13m kubelet Pulling image "ubuntu:latest"
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Normal Pulled 13m kubelet Successfully pulled image "ubuntu:latest" in 3.148272011s (3.148286457s including waiting)
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Normal Created 13m kubelet Created container sidecar-container
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Normal Started 13m kubelet Started container sidecar-container
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Normal Pulling 12m (x3 over 13m) kubelet Pulling image "nginx:latests"
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Warning Failed 12m (x3 over 13m) kubelet Failed to pull image "nginx:latests": rpc error: code = NotFound desc = failed to pull and unpack image "docker.io/library/nginx:latests": failed to resolve reference "docker.io/library/nginx:latests": docker.io/library/nginx:latests: not found
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Warning Failed 12m (x3 over 13m) kubelet Error: ErrImagePull
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Warning Failed 12m (x6 over 13m) kubelet Error: ImagePullBackOff
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Normal BackOff 3m32s (x43 over 13m) kubelet Back-off pulling image "nginx:latests"
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```
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> We see there are two container where nignx is getting failed to pull. It seems image tag issue.
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3. Let's create a `pod.yml` file from the `webserver` pod
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```sh
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kubectl get pod webserver -o yaml > pod.yml
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```
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4. Update the nginx container image tag
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```sh
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vi pod.yml
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```
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> let's change nginx container image: `nginx:latests` to `nginx:latest`
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```YAML
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apiVersion: v1
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kind: Pod
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metadata:
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annotations:
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kubectl.kubernetes.io/last-applied-configuration: |
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{"apiVersion":"v1","kind":"Pod","metadata":{"annotations":{},"labels":{"app":"web-app"},"name":"webserver","namespace":"default"},"spec":{"containers":[{"image":"nginx:latests","name":"nginx-container","volumeMounts":[{"mountPath":"/var/log/nginx","name":"shared-logs"}]},{"command":["sh","-c","while true; do cat /var/log/nginx/access.log /var/log/nginx/error.log; sleep 30; done"],"image":"ubuntu:latest","name":"sidecar-container","volumeMounts":[{"mountPath":"/var/log/nginx","name":"shared-logs"}]}],"volumes":[{"emptyDir":{},"name":"shared-logs"}]}}
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creationTimestamp: "2025-09-16T15:08:31Z"
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labels:
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app: web-app
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name: webserver
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namespace: default
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resourceVersion: "2169"
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uid: a9c988ea-ed2f-4f6d-92eb-ed282f273c6c
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spec:
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containers:
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- image: nginx:latest
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imagePullPolicy: IfNotPresent
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name: nginx-container
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resources: {}
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terminationMessagePath: /dev/termination-log
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terminationMessagePolicy: File
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volumeMounts:
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- mountPath: /var/log/nginx
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name: shared-logs
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- mountPath: /var/run/secrets/kubernetes.io/serviceaccount
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name: kube-api-access-cmx2n
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readOnly: true
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- command:
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- sh
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- -c
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- while true; do cat /var/log/nginx/access.log /var/log/nginx/error.log; sleep
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30; done
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image: ubuntu:latest
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imagePullPolicy: Always
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name: sidecar-container
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resources: {}
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terminationMessagePath: /dev/termination-log
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terminationMessagePolicy: File
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volumeMounts:
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- mountPath: /var/log/nginx
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name: shared-logs
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- mountPath: /var/run/secrets/kubernetes.io/serviceaccount
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name: kube-api-access-cmx2n
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readOnly: true
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dnsPolicy: ClusterFirst
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enableServiceLinks: true
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nodeName: kodekloud-control-plane
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preemptionPolicy: PreemptLowerPriority
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priority: 0
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restartPolicy: Always
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schedulerName: default-scheduler
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securityContext: {}
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serviceAccount: default
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serviceAccountName: default
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terminationGracePeriodSeconds: 30
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tolerations:
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- effect: NoExecute
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key: node.kubernetes.io/not-ready
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operator: Exists
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tolerationSeconds: 300
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- effect: NoExecute
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key: node.kubernetes.io/unreachable
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operator: Exists
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tolerationSeconds: 300
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volumes:
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- emptyDir: {}
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name: shared-logs
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- name: kube-api-access-cmx2n
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projected:
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defaultMode: 420
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sources:
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- serviceAccountToken:
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expirationSeconds: 3607
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path: token
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- configMap:
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items:
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- key: ca.crt
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path: ca.crt
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name: kube-root-ca.crt
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- downwardAPI:
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items:
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- fieldRef:
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apiVersion: v1
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fieldPath: metadata.namespace
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path: namespace
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status:
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conditions:
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- lastProbeTime: null
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lastTransitionTime: "2025-09-16T15:08:31Z"
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status: "True"
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type: Initialized
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- lastProbeTime: null
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lastTransitionTime: "2025-09-16T15:08:31Z"
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message: 'containers with unready status: [nginx-container]'
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reason: ContainersNotReady
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status: "False"
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type: Ready
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- lastProbeTime: null
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lastTransitionTime: "2025-09-16T15:08:31Z"
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message: 'containers with unready status: [nginx-container]'
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reason: ContainersNotReady
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status: "False"
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type: ContainersReady
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- lastProbeTime: null
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lastTransitionTime: "2025-09-16T15:08:31Z"
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status: "True"
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type: PodScheduled
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containerStatuses:
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- image: nginx:latests
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imageID: ""
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lastState: {}
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name: nginx-container
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ready: false
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restartCount: 0
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started: false
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state:
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waiting:
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message: Back-off pulling image "nginx:latests"
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reason: ImagePullBackOff
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- containerID: containerd://675404859dcc69803025764a26dafaf3d651c8827af1c6379ad10091f77b048d
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image: docker.io/library/ubuntu:latest
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imageID: docker.io/library/ubuntu@sha256:590e57acc18d58cd25d00254d4ca989bbfcd7d929ca6b521892c9c904c391f50
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lastState: {}
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name: sidecar-container
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ready: true
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restartCount: 0
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started: true
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state:
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running:
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startedAt: "2025-09-16T15:08:35Z"
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hostIP: 172.17.0.2
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phase: Pending
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podIP: 10.244.0.5
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podIPs:
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- ip: 10.244.0.5
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qosClass: BestEffort
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startTime: "2025-09-16T15:08:31Z"
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```
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5. lets re-create the pod
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```sh
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kubectl delete pod webserver
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kubectl apply -f pod.yml
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```
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6. We can verify:
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```sh
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kubectl get pod webserver
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```
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> we can see the pod is running
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7. Access webpage
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```sh
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curl localhost:8080
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```

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