How to debug when Kubernetes nodes are in 'Not Ready' state

Question

I initialized the master node and add 2 worker nodes, but only master and one of the worker node show up when I run the following command:

kubectl get nodes
         


        

Answer 1

Steps to debug:-

In case you face any issue in kubernetes, first step is to check if kubernetes self applications are running fine or not.

Command to check:- kubectl get pods -n kube-system

If you see any pod is crashing, check it's logs

if getting NotReady state error, verify network pod logs.

if not able to resolve with above, follow below steps:-

1. kubectl get nodes # Check which node is not in ready state

2. kubectl describe node nodename #nodename which is not in readystate

3. ssh to that node

4. execute systemctl status kubelet # Make sure kubelet is running

5. systemctl status docker # Make sure docker service is running

6. journalctl -u kubelet # To Check logs in depth

Most probably you will get to know about error here, After fixing it reset kubelet with below commands:-

6. systemctl daemon-reload
7. systemctl restart kubelet

In case you still didn't get the root cause, check below things:-

8. Make sure your node has enough space and memory. Check for /var directory space especially. command to check: -df -kh, free -m

9. Verify cpu utilization with top command. and make sure any process is not taking an unexpected memory.