创建ReplicaSet

ReplicaSet的配置如下

apiVersion: apps/v1

kind: ReplicaSet

metadata:

name: myapp

namespace: default

spec:

replicas: 2

selector:

matchLabels:

app: myapp

release: canary

template:

metadata:

name: myapp-pod

labels:

app: myapp

release: canary

environment: qa

spec:

containers:

- name: myapp-container

image: ikubernetes/myapp:v1

ports:

- name: http

containerPort: 80

在这个ReplicaSet中，我们设置了两个label，app=myapp, release=canary , 创建rs后，查看

[root@master manifests]# kubectl create -f rs-demo.yaml --dry-run

replicaset.apps/myapp created (dry run)

[root@master manifests]# kubectl create -f rs-demo.yaml

replicaset.apps/myapp created

[root@master manifests]# kubectl get pods

NAME READY STATUS RESTARTS AGE

myapp-bj795 1/1 Running 0 18s

myapp-blmx8 1/1 Running 0 18s

[root@master manifests]# vim rs-demo.yaml

[root@master manifests]# kubectl get pods --show-labels

NAME READY STATUS RESTARTS AGE LABELS

myapp-b8sb5 1/1 Running 0 5m app=myapp,environment=qa,release=canary

myapp-blmx8 1/1 Running 0 8m app=myapp,environment=qa,release=canary

[root@master manifests]# kubectl get rs

NAME DESIRED CURRENT READY AGE

myapp 2 2 2 39s

实验

ReplicaSet会通过label app=myapp, release=canary 来筛选Pod，并且设定的符合该label的Pod副本应该为2个。

pod-demo.yaml文件的内容如下:

apiVersion: v1

kind: Pod

metadata:

name: pod-demo

namespace: default

labels:

app: myapp

tier: frontend

spec:

containers:

- name: myapp

image: ikubernetes/myapp:v1

ports:

- name: http

containerPort: 80

- name: https

containerPort: 443

- name: busybox

image: busybox:latest

#ImagePullPolicy: IfNotPresent

command:

- "/bin/sh"

- "-c"

- "sleep 3600"

此时，我们创建另一个pod

[root@master manifests]# kubectl create -f pod-demo.yaml

pod/pod-demo created

[root@master manifests]# kubectl get pods --show-labels

NAME READY STATUS RESTARTS AGE LABELS

myapp-b8sb5 1/1 Running 0 5m app=myapp,environment=qa,release=canary

myapp-blmx8 1/1 Running 0 7m app=myapp,environment=qa,release=canary

pod-demo 2/2 Running 0 11s app=myapp,tier=frontend

可以看到，pod-demo的label为 app=myapp,tier=frontend ，我们尝试给pod-demo添加一个label release=canary ，看下会出现什么效果。

[root@master manifests]# kubectl label pods pod-demo release=canary

pod/pod-demo labeled

[root@master manifests]# kubectl get pods --show-labels

NAME READY STATUS RESTARTS AGE LABELS

myapp-b8sb5 1/1 Running 0 5m app=myapp,environment=qa,release=canary

myapp-blmx8 1/1 Running 0 8m app=myapp,environment=qa,release=canary

pod-demo 2/2 Terminating 0 34s app=myapp,release=canary,tier=frontend

可以发现： pod-demo的状态已经为 Terminating。 说明ReplicaSet通过标签选择器获取到了三个副本，然后预期的副本数被设定为2，它随机杀掉了一个。

应该是随机的， 不过，我测试了几次，都是把新建的pod-demo杀掉了。