kubectl kubectl apply do nothing

user_14248016 0
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I have existing deployments in k8s, I would like to update container, I updated docker image tag (new unique id) in deployment and run:

kubectl apply -f testdeploy.yml --namespace=myapp

Output is: deployment.apps/fakename configured

But nothing happens.

When I run kubectl get pods --namespace=myapp I can see only one old pod with old age.

Sometimes is working, sometimes not, why?

What is wrong?

kubernetes deployment
3 Answers

try describing the deployment and see the events

kubectl describe <deployment-name> --namespace=myapp

or

kubectl get events --namespace=myapp

to understand what is happening.

try checking whether new replicas has been created for changed deployment container image.

kubectl get rs -n myapp

check the number of replicas expected example when you do kubectl get rs:

NAME                                DESIRED   CURRENT   READY   AGE
<deployment-name>-58ffbb8b76         0         0         0       10s

maybe few more details would be helpful to understand why was nothing happening when you try to deploy.

kubernetes has nice documentation check this.

https://kubernetes.io/docs/tasks/debug-application-cluster/debug-application-introspection/

user_117797040

Try with adding ImagePullPolicy: Always as the below:

    spec:
      containers:
      - image: <YOUR_IMAGE>:<YOUR_TAG>
        imagePullPolicy: Always
user_108917500

You need to delete your deployment kubectl delete -f testdeploy.yml --namespace=myapp and then create it again kubectl apply -f testdeploy.yml --namespace=myapp it will fetch the new image, or you can edit your deployment file as shown below and introduce rollingupdate and then when you update your image you can simply type kubectl rollout restart deploy deployment_name_mentioned_in_manifest -n namespace this will provision a new pod while the old stays and fetch the new image, once that is done old pod will get deleted and the new pod will have the latest image.

Example with the manifest file below if i want to pull latest image i will type kubectl rollout restart deploy nginx -n test

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
  namespace: test
spec:
  replicas: 1
  selector:
    matchLabels:
      name: nginx
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable: 1
      maxSurge: 1
  template:
    metadata:
      labels:
        name: nginx
    spec:
      containers:
      - name:  nginx
        image: nginx:latest
        imagePullPolicy: Always
        ports:
        - containerPort: 80
          hostPort: 80
        - containerPort: 443
          hostPort: 443
        readinessProbe:
          tcpSocket:
            port: 443
            port: 80
          initialDelaySeconds: 5
          periodSeconds: 5
user_130276900
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