What is Kubernetes Node Lifecycle?

Question

Accepted Answer

**Node Lifecycle** — conditions and taints that affect Pod scheduling.

```yaml
# Node with taints
apiVersion: v1
kind: Node
metadata:
  name: gpu-node
spec:
  taints:
  - key: nvidia.com/gpu
    effect: NoSchedule
    value: "present"
  - key: node.kubernetes.io/not-ready
    effect: NoExecute
    value: "true"
    tolerationSeconds: 300
  unschedulable: false
  providerID: aws:///us-west-2a/i-1234567890abcdef0
```

```bash
# Check node conditions
kubectl get nodes -o custom-columns=
  NAME:.metadata.name,
  STATUS:.status.conditions[-1].type,
  READY:.status.conditions[-1].status,
  AGE:.metadata.creationTimestamp

# Detailed conditions
kubectl describe node node-1 | grep -A 10 "Conditions:"

# Taints and tolerations
kubectl describe node node-1 | grep -A 5 "Taints:"

# Cordon (mark unschedulable)
kubectl cordon node-1
kubectl uncordon node-1

# Drain (evict Pods, then cordon)
kubectl drain node-1 --ignore-daemonsets --delete-emptydir-data --force
kubectl drain node-1 --ignore-daemonsets --force --timeout=300s

# Label and annotate
kubectl label node node-1 disktype=ssd
kubectl annotate node node-1 node.alpha.kubernetes.io/ttl=0
```

**Conditions:**
- Ready: node is healthy.
- MemoryPressure: low memory.
- DiskPressure: low disk.
- PIDPressure: too many processes.
- NetworkUnavailable: no network.

**Taint Effects:**
- NoSchedule: don't schedule new Pods.
- PreferNoSchedule: try to avoid.
- NoExecute: evict existing Pods.

DevOps: What is Kubernetes Node Lifecycle?