# 1. 创建 Pod 并实时观察
kubectl run lifecycle-pod --image=nginx:alpine --restart=Never

# 在另一个终端 watch
kubectl get pod lifecycle-pod -w
# 观察：Pending → ContainerCreating → Running

# 2. 查看详细信息
kubectl describe pod lifecycle-pod
# 重点关注 Events 部分

# 3. 进入容器看运行细节
kubectl exec lifecycle-pod -- cat /etc/nginx/conf.d/default.conf

# 4. 删除并观察终止过程（默认 30 秒优雅终止）
kubectl delete pod lifecycle-pod &
kubectl get pod lifecycle-pod -w
# 观察：Running → Terminating → 消失

# 5. 创建带较长 terminationGracePeriodSeconds 的 Pod
kubectl run graceful-pod --image=nginx:alpine --restart=Never \
  --overrides='{"spec":{"terminationGracePeriodSeconds":60}}'

# 验证
kubectl get pod graceful-pod -o jsonpath='{.spec.terminationGracePeriodSeconds}'
kubectl delete pod graceful-pod

# 创建 Sidecar Pod：主容器写日志，Sidecar 读取
cat <<'EOF' | kubectl apply -f -
apiVersion: v1
kind: Pod
metadata:
  name: sidecar-demo
spec:
  containers:
  - name: app
    image: busybox:1.36
    args:
    - /bin/sh
    - -c
    - |
      i=0
      while true; do
        echo "$(date): log entry $i" >> /var/log/app.log
        i=$((i+1))
        sleep 2
      done
    volumeMounts:
    - name: logs
      mountPath: /var/log

  - name: log-reader
    image: busybox:1.36
    args:
    - /bin/sh
    - -c
    - tail -f /var/log/app.log
    volumeMounts:
    - name: logs
      mountPath: /var/log

  volumes:
  - name: logs
    emptyDir: {}
EOF

# 验证 Sidecar 能读到主容器的日志
kubectl logs sidecar-demo -c log-reader --tail=10

# 查看两个容器的状态
kubectl get pod sidecar-demo
# READY 2/2

# 清理
kubectl delete pod sidecar-demo

# 第一步：创建需要等待的依赖 Service
kubectl create deploy backend --image=nginx:alpine --replicas=1
kubectl expose deploy backend --port=80

# 第二步：创建带 InitContainer 的 Pod
cat <<'EOF' | kubectl apply -f -
apiVersion: v1
kind: Pod
metadata:
  name: init-demo
spec:
  initContainers:
  - name: wait-for-backend
    image: busybox:1.36
    command:
    - sh
    - -c
    - |
      echo "Waiting for backend service..."
      until wget -q --spider http://backend-service.default.svc.cluster.local; do
        echo "Backend not ready yet..."
        sleep 2
      done
      echo "Backend is ready!"
  containers:
  - name: app
    image: busybox:1.36
    command:
    - sh
    - -c
    - echo "Main app started!" && sleep 3600
EOF

# 观察 InitContainer 执行
kubectl get pod init-demo -w
# 看到 STATUS 列：Init:0/1 → PodInitializing → Running

# 查看 InitContainer 日志
kubectl logs init-demo -c wait-for-backend

# 清理
kubectl delete pod init-demo
kubectl delete deploy backend
kubectl delete svc backend

cat <<'EOF' | kubectl apply -f -
apiVersion: v1
kind: Pod
metadata:
  name: liveness-demo
spec:
  containers:
  - name: unhealthy
    image: busybox:1.36
    command:
    - sh
    - -c
    - |
      touch /tmp/healthy
      # 30 秒后删除健康标志文件，模拟程序故障
      sleep 30
      rm /tmp/healthy
      sleep 3600
    livenessProbe:
      exec:
        command:
        - cat
        - /tmp/healthy
      initialDelaySeconds: 5
      periodSeconds: 5
      failureThreshold: 3
EOF

# 持续观察 Pod 状态
kubectl get pod liveness-demo -w

# 另一个终端查看事件
kubectl describe pod liveness-demo | grep -A5 "Events"

# 预期：约 30 + 5*3 = 45 秒后 Pod 被重启
kubectl get pod liveness-demo
# RESTARTS 列从 0 递增

# 清理
kubectl delete pod liveness-demo

cat <<'EOF' | kubectl apply -f -
apiVersion: apps/v1
kind: Deployment
metadata:
  name: readiness-demo
spec:
  replicas: 2
  selector:
    matchLabels:
      app: readiness-demo
  template:
    metadata:
      labels:
        app: readiness-demo
    spec:
      containers:
      - name: nginx
        image: nginx:alpine
        ports:
        - containerPort: 80
        readinessProbe:
          httpGet:
            path: /
            port: 80
          initialDelaySeconds: 3
          periodSeconds: 3
---
apiVersion: v1
kind: Service
metadata:
  name: readiness-svc
spec:
  selector:
    app: readiness-demo
  ports:
  - port: 80
    targetPort: 80
EOF

# 查看 Endpoint 变化
kubectl get endpoints readiness-svc -w
# Pod Ready 后 Endpoint 出现

# 模拟 Pod 不健康：修改 nginx 配置让 / 返回错误
# （略，比赛环境可能需要替代方案）

# 清理
kubectl delete deploy readiness-demo
kubectl delete svc readiness-svc

# 创建一个会立即退出的 Pod
kubectl run crash-demo --image=busybox:1.36 --restart=Always -- /bin/false

# 观察状态
kubectl get pod crash-demo
# STATUS: CrashLoopBackOff

# 查看上一次崩溃的日志
kubectl logs crash-demo --previous

# 查看事件
kubectl describe pod crash-demo | grep -A10 Events

# 进入容器调试（如果容器立即退出，无法 exec）
kubectl run debug-pod --image=busybox:1.36 --restart=Never -it --rm -- sh

# 清理
kubectl delete pod crash-demo

# 创建一个配置了错误端口的 readinessProbe
cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Pod
metadata:
  name: ready-fail
spec:
  containers:
  - name: nginx
    image: nginx:alpine
    readinessProbe:
      httpGet:
        path: /
        port: 8080    # 错误端口！nginx 在 80
      initialDelaySeconds: 3
      periodSeconds: 3
EOF

# 观察
kubectl get pod ready-fail
# STATUS: Running   READY: 0/1

kubectl describe pod ready-fail | grep -A5 Readiness
# Warning  Unhealthy  Readiness probe failed: dial tcp ...:8080: connect: connection refused

# 修复：正确配置端口 → 直接重建 Pod（探针不可变）
kubectl delete pod ready-fail