4.3 使用 ReplicaSet 而不是 ReplicationController

ReplicaSet 是新一代 ReplicationController (将被弃用).

4.3.1 比较 ReplicaSet 和 ReplicationController

• 行为完全相同
• ReplicaSet 的 pod 选择器表达能力更强

4.3.2 定义 ReplicaSet

模拟:

apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: hello-rs
spec:
  replicas: 3
  selector:
    matchLabels:
      app: rs
  template:
    metadata:
      labels:
        app: rs
    spec:
      containers:
        - image: jdxj/study_kubernetes:v0.3.0
          name: test-study-k8s
          ports:
            - containerPort: 8080
              protocol: TCP

API 版本的属性:

• API 组 (apps)
• 实际的 API 版本 (v1beta2)

4.3.3 创建和检查 ReplicaSet

查看:

$ kubectl get rs
NAME       DESIRED   CURRENT   READY   AGE
hello-rs   3         3         3       108s

$ kubectl describe rs
Name:         hello-rs
Namespace:    default
Selector:     app=rs
Labels:       <none>
Annotations:  <none>
Replicas:     3 current / 3 desired
Pods Status:  3 Running / 0 Waiting / 0 Succeeded / 0 Failed
Pod Template:
  Labels:  app=rs
  Containers:
   test-study-k8s:
    Image:        jdxj/study_kubernetes:v0.3.0
    Port:         8080/TCP
    Host Port:    0/TCP
    Environment:  <none>
    Mounts:       <none>
  Volumes:        <none>
Events:
  Type    Reason            Age    From                   Message
  ----    ------            ----   ----                   -------
  Normal  SuccessfulCreate  2m18s  replicaset-controller  Created pod: hello-rs-kzss2
  Normal  SuccessfulCreate  2m18s  replicaset-controller  Created pod: hello-rs-5p6g6
  Normal  SuccessfulCreate  2m18s  replicaset-controller  Created pod: hello-rs-s8tlp

4.3.4 使用 ReplicaSet 的更富表达力的标签选择器

matchExpressions 选择器:

组成:

• key
• operator
• values

运算符:

多个表达式之间是 “与” 的关系.

4.3.5 ReplicaSet 小结

删除 ReplicaSet:

• 会删除 pod

$ kubectl delete rs kubia