k8s_diagnosis

k8s diagnosis

TEST for data persistence:
==========================
kubectl exec nodehelloworld.example.com -- touch /app/test.txt
        Then kill the pod and redeploy it
        Then run: kubectl exec nodehelloworld.example.com -- ls /app
          If persistence works then test.txt would still be there.


kubectl get service

NAME                     TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)          AGE
hello-minikube           NodePort    10.0.0.175   <none>        8080:31094/TCP   33d
kubernetes               ClusterIP   10.0.0.1     <none>        443/TCP          33d
nodehelloworld-service   NodePort    10.0.0.247   <none>        3000:32330/TCP   2h

kubectl describe service nodehelloworld-service

Name:                     nodehelloworld-service
Namespace:                default
Labels:                   app=helloworld
Annotations:              <none>
Selector:                 app=helloworld
Type:                     NodePort
IP:                       10.0.0.247
Port:                     <unset>  3000/TCP
TargetPort:               3000/TCP
NodePort:                 <unset>  32330/TCP
Endpoints:                172.17.0.5:3000
Session Affinity:         None
External Traffic Policy:  Cluster
Events:                   <none>

Can connect to the endpoint from another pod
  ---Endpoints:                172.17.0.5:3000
   OR
Use the nodeport because it is a static port
  ---NodePort:                 <unset>  32330/TCP

LAUNCH another pod with busybox:

kubectl run -i --tty busybox --image=busybox --restart=Never -- sh

      If you don't see a command prompt, try pressing enter.
      / #

Then you can execute commands into the cluster...
      kubectl run -i --tty busybox --image=busybox --restart=Never -- sh
      If you don't see a command prompt, try pressing enter.
      / # ls
      RESULTS: bin   dev   etc   home  proc  root  sys   tmp   usr   var
      /  #

      / # curl
      sh: curl: not found
      / #

      to kill the subybox pod:  kubectl delete pod -l run=busybox

      kubectl run -i --tty busybox --image=busybox --restart=Never -- sh
      If you don't see a command prompt, try pressing enter.
      / # telnet 172.17.0.5 3000
      GET /

      Stuck no results...


ONE ANSWER
Edward — Instructor  · 3 months ago
Hi Mohan,

Check firewall logs if possible, check your systemd logs if you're using systemd,
check flannel logs (probably also in systemd). There's not really a list of commands
 or procedure for things like this, you'll just have to keep debugging every single
  component until you find what's blocking it. If you're on a enterprise network,
  it's probably something blocking ports between the instances. Make sure you have
  port 8285 udp open for network encapsulation.

-Edward