通过命令`kubectl scale`可以进行手动扩缩容，使用参数`--replicas`指定需要增加或是减少 Pod 的数量到某个指定的数字。 下面通过一个实例来体会手动扩缩容的效果，在`/home/shiyanlou`目录下新建`nginx-deployment.yaml`文件，并向其中写入如下内容： ~~~txt apiVersion: apps/v1 kind: Deployment metadata: name: nginx-deployment spec: selector: matchLabels: app: nginx replicas: 3 template: metadata: labels: app: nginx spec: containers: - name: nginx image: nginx:1.7.9 ports: - containerPort: 80 ~~~ 执行创建： ~~~bash $ kubectl create -f nginx-deployment.yaml deployment.apps/nginx-deployment created ~~~ 现在我们预期会有 3 个 nginx-deployment Pod 副本运行中： ~~~bash $ kubectl get pods NAME READY STATUS RESTARTS AGE nginx-deployment-5754944d6c-hkz57 1/1 Running 0 55s nginx-deployment-5754944d6c-jvhwq 1/1 Running 0 55s nginx-deployment-5754944d6c-z7ccp 1/1 Running 0 55s ~~~ 首先，我们进行扩容，将 nginx-deployment Pod 副本数量从 3 个扩容到 5 个： ~~~bash # 执行扩容 $ kubectl scale deployment nginx-deployment --replicas 5 deployment.extensions/nginx-deployment scaled # 可以看到有两个新创建的 Pod $ kubectl get pods NAME READY STATUS RESTARTS AGE nginx-deployment-5754944d6c-gtrgm 1/1 Running 0 9s nginx-deployment-5754944d6c-hkz57 1/1 Running 0 4m24s nginx-deployment-5754944d6c-jvhwq 1/1 Running 0 4m24s nginx-deployment-5754944d6c-px8m4 1/1 Running 0 9s nginx-deployment-5754944d6c-z7ccp 1/1 Running 0 4m24s ~~~ 然后，我们进行缩容，将 nginx-deployment Pod 副本数量从 5 个缩容到 1 个： ~~~bash # 执行缩容 $ kubectl scale deployment nginx-deployment --replicas 1 deployment.extensions/nginx-deployment scaled # 从结果中可以看出，系统 kill 掉了一些运行中的 Pod，只保留了一个 Pod 来实现缩容 $ kubectl get pods NAME READY STATUS RESTARTS AGE nginx-deployment-5754944d6c-jvhwq 1/1 Running 0 9m2s ~~~