How to fix DaemonSet pod not ready, readiness probe failing in Kubernetes

# Get DaemonSet YAML:
kubectl get daemonset -n <namespace> <name> -o yaml

# Look for readinessProbe and livenessProbe:
kubectl get daemonset -n <namespace> <name> -o yaml | grep -A 10 "readinessProbe\|livenessProbe"

# Check exact probe settings:
# - initialDelaySeconds
# - timeoutSeconds
# - periodSeconds
# - failureThreshold

# Check pod logs:
kubectl logs -n <namespace> <pod-name>

# Check probe endpoint directly:
kubectl exec -n <namespace> <pod-name> -- curl -v http://localhost:8080/health

# Check application startup time:
kubectl logs -n <namespace> <pod-name> | head -20

# Look for how long app takes to be ready

kubectl edit daemonset -n <namespace> <name>

readinessProbe:
  httpGet:
    path: /health
    port: 8080
  initialDelaySeconds: 60    # Increased from 10
  timeoutSeconds: 5
  periodSeconds: 10
  failureThreshold: 3

# Force rollout:
kubectl rollout restart daemonset -n <namespace> <name>

readinessProbe:
  httpGet:
    path: /health
    port: 8080
  initialDelaySeconds: 30
  timeoutSeconds: 10        # Increased from 1
  periodSeconds: 10
  failureThreshold: 5       # Increased from 3

# Get pod IP:
kubectl get pod -n <namespace> <pod-name> -o jsonpath='{.status.podIP}'

# Test endpoint from another pod:
kubectl run debug --rm -it --image=alpine -- sh
# Inside pod:
apk add curl
curl -v http://<pod-ip>:8080/health

# Or exec directly:
kubectl exec -n <namespace> <pod-name> -- curl -v http://localhost:8080/health

# Check response code - should be 200

# Check resource limits:
kubectl describe pod -n <namespace> <pod-name> | grep -A 3 "Limits\|Requests"

# Check if pod is hitting limits:
kubectl top pod -n <namespace> <pod-name>

# Check node for resource pressure:
kubectl describe node <node-name> | grep -A 5 "Allocated resources\|Conditions"

# If resources are tight, increase limits:
kubectl edit daemonset -n <namespace> <name>

# Check application logs for errors:
kubectl logs -n <namespace> <pod-name> --previous  # If pod crashed and restarted

# Common issues:
# - Missing environment variables
# - Database connection failures
# - Configuration loading errors
# - Port already in use

# Set/verify environment variables:
kubectl get daemonset -n <namespace> <name> -o yaml | grep -A 10 env:

# Check if port is already in use:
kubectl exec -n <namespace> <pod-name> -- netstat -tlnp | grep 8080

# Watch pod transitions:
kubectl get pods -n <namespace> -w | grep <pod-name>

# Check if pod becomes Ready:
kubectl get pods -n <namespace> <pod-name> -o wide

# Monitor probe results in events:
kubectl describe pod -n <namespace> <pod-name> | tail -20

# Once ready, verify all DaemonSet pods are ready:
kubectl get daemonset -n <namespace> <name>
# READY column should show N/N where N is number of nodes