My Kubernetes pods are restarting frequently. Can any one assist me to figure out root cause of pods restart problem.

There are several reasons for pods can restart In a Kubernetes environment. Here are the common causes that might trigger a pod restart -

1. Container Crashes (Application Errors) : If the application crashes due to bug , unhandled exceptions, out of memory error etc. Kubernetes will attempt to restart the pod to recover. you can check log of pods using   command  kubectl logs <pod-name>
2. Resource (CPU or Memory) Limit Exceeded : If you set limit on CPU and Memory on configuration and pods exceed these limit it may be throttled or evicted, leading to a restart. if container uses more memory than the define limit in this case pods will kill and restart you can check logs using command kubectl describe pod <pod-name>
3. Liveness Probe Failures : Liveness probe is a mechanism that checks whether your application is healthy or not. If the liveness probe fails repeatedly (does not get 200 OK response or equivalent). Kubernetes will restart the pod, assuming pods in a bad state.
4. Node Issues (Node Failures or Reboots) : If the node where the pod is running fails, reboots, or gets drained (for upgrades or maintenance) the pod will be evicted and restarted on another node.
5. Eviction Due to Node Resource Pressure : When a node faces high resource pressure (memory, disk or CPU) Kubernetes may evict pods to free up resources. This typically happens when the node itself is running low on available memory or disk.
6. Deployment or StatefulSet Rolling Updates : During the deployment of new version of your application, Kubernetes may restart the pods as part of a rolling update. This is an intentional restart to roll out new configurations or application versions.
7. Failed Init Containers : Init container run before the main container. If an init container fails. It may cause the pod to be restarted.
8. Kubelet or Docker Issues : If the Kubelet (Kubernetes agent running on a node) or the container runtime (e.g., Docker) encounters issues, pods may be restarted. Sometimes upgrading or restarting the Kubelet or Docker can lead to pod restarts.
9. Configuration Changes (ConfigMap, Secret Updates) : If a pod is configured to reload ConfigMaps or Secrets and these configurations are updated. Kubernetes may restart the pod to apply the new configurations. It ensures that the pod runs with the latest configuration.
10. Kubernetes Scheduler Reassignment : Sometimes, the Kubernetes scheduler may reassign a pod to a different node due to scheduling changes, resource optimization or affinity/anti-affinity rules. It can trigger a pod restart.

How to Debug Pod Restarts :

• Check Pod Status : kubectl get pod <pod-name> -o wide
• Describe the Pod : Fetch detailed information about the pod's status, events and restart reasons 
  kubectl describe pod <pod-name>
• Check Logs : kubectl logs <pod-name>
• Check Node Status : 
  kubectl get nodes 
kubectl describe node <node-name>
• Check Resource Usage (CPU , Memory ) : kubectl top pod <pod-name>