Kubernetes 1.19.0——服务svc(1)

时间:2022-07-28
本文章向大家介绍Kubernetes 1.19.0——服务svc(1)，主要内容包括其使用实例、应用技巧、基本知识点总结和需要注意事项，具有一定的参考价值，需要的朋友可以参考一下。
创建一个deploy
[root@vms61 chap9-svc]# kubectl create deployment web1 --image=nginx --dry-run=client -o yaml > web1.yaml
[root@vms61 chap9-svc]# vi web1.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    app: web1
  name: web1
spec:
  replicas: 3
  selector:
    matchLabels:
      app: web1
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: web1
    spec:
      containers:
      - image: nginx
        imagePullPolicy: IfNotPresent
        name: nginx
        resources: {}
status: {}
[root@vms61 chap9-svc]# kubectl apply -f web1.yaml 
deployment.apps/web1 created
[root@vms61 chap9-svc]# kubectl get pods
NAME                    READY   STATUS    RESTARTS   AGE
web1-5bfb6d8dcc-jqrfl   1/1     Running   0          4s
web1-5bfb6d8dcc-nggqm   1/1     Running   0          4s
web1-5bfb6d8dcc-qrhtj   1/1     Running   0          4s
[root@vms61 chap9-svc]# kubectl get pods -o wide
NAME                    READY   STATUS    RESTARTS   AGE   IP              NODE    NOMINATED NODE   READINESS GATES
web1-5bfb6d8dcc-jqrfl   1/1     Running   0          55s   10.244.196.36   vms62   <none>           <none>
web1-5bfb6d8dcc-nggqm   1/1     Running   0          55s   10.244.196.37   vms62   <none>           <none>
web1-5bfb6d8dcc-qrhtj   1/1     Running   0          55s   10.244.116.8    vms63   <none>           <none>

每个pod的IP只能是集群内部可访问，集群里的pod——不管是哪个ns或在哪个节点，都是可以的

对deploy来创建的SVC，给pod指定标签是app1:web1和app2:web2

SVC定位的是app1:web1和app2:web2

注意这里如果指定了port为非80端口，curl的时候需要加上写明

[root@vms61 chap9-svc]# cat web1.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    aa: bb
  name: web1
spec:
  replicas: 3
  selector:
    matchLabels:
      app2: web2
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        app1: web1
        app2: web2
    spec:
      containers:
      - image: nginx
        imagePullPolicy: IfNotPresent
        name: nginx
        resources: {}
status: {}
[root@vms61 chap9-svc]# kubectl apply -f web1.yaml 
deployment.apps/web1 created
[root@vms61 chap9-svc]# kubectl expose --name=svc1 deployment web1 --port=80 --target-port=80
service/svc1 exposed
[root@vms61 chap9-svc]# kubectl get svc
NAME   TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)   AGE
svc1   ClusterIP   10.107.89.230   <none>        80/TCP    7s
[root@vms61 chap9-svc]# kubectl get pods -o wide
NAME                    READY   STATUS    RESTARTS   AGE   IP              NODE    NOMINATED NODE   READINESS GATES
web1-6464d54bd7-dt9qt   1/1     Running   0          70s   10.244.196.38   vms62   <none>           <none>
web1-6464d54bd7-vtkwz   1/1     Running   0          70s   10.244.116.6    vms63   <none>           <none>
web1-6464d54bd7-xfgth   1/1     Running   0          70s   10.244.196.40   vms62   <none>           <none>
[root@vms61 chap9-svc]# kubectl get pods --show-labels 
NAME                    READY   STATUS    RESTARTS   AGE   LABELS
web1-6464d54bd7-dt9qt   1/1     Running   0          79s   app1=web1,app2=web2,pod-template-hash=6464d54bd7
web1-6464d54bd7-vtkwz   1/1     Running   0          79s   app1=web1,app2=web2,pod-template-hash=6464d54bd7
web1-6464d54bd7-xfgth   1/1     Running   0          79s   app1=web1,app2=web2,pod-template-hash=6464d54bd7
而默认会使用后面定义的app2:web2
[root@vms61 chap9-svc]# kubectl get svc -o wide
NAME   TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)   AGE     SELECTOR
svc1   ClusterIP   10.107.89.230   <none>        80/TCP    8m33s   app2=web2
[root@vms61 chap9-svc]# kubectl describe svc svc1
Name:              svc1
Namespace:         chap9-svc
Labels:            aa=bb
Annotations:       <none>
Selector:          app2=web2
Type:              ClusterIP
IP:                10.107.89.230
Port:              <unset>  80/TCP
TargetPort:        80/TCP
Endpoints:         10.244.116.6:80,10.244.196.38:80,10.244.196.40:80
Session Affinity:  None
Events:            <none>
[root@vms61 chap9-svc]# kubectl get pods -o wide
NAME                    READY   STATUS    RESTARTS   AGE     IP              NODE    NOMINATED NODE   READINESS GATES
web1-6464d54bd7-dt9qt   1/1     Running   0          8m46s   10.244.196.38   vms62   <none>           <none>
web1-6464d54bd7-vtkwz   1/1     Running   0          8m46s   10.244.116.6    vms63   <none>           <none>
web1-6464d54bd7-xfgth   1/1     Running   0          8m46s   10.244.196.40   vms62   <none>           <none>

那如果想使用app1: web1来定位呢？当然可以

通过如下命令即可，请自行测试

kubectl expose --name=svc1 deployment web1 --port=80 --target-port=80 --selector=app1=web1

添加一些测试数据后访问svc的IP，直接转发至后端
[root@vms61 chap9-svc]# kubectl get pods -o wide
NAME                    READY   STATUS    RESTARTS   AGE   IP              NODE    NOMINATED NODE   READINESS GATES
web1-6464d54bd7-dt9qt   1/1     Running   0          13m   10.244.196.38   vms62   <none>           <none>
web1-6464d54bd7-vtkwz   1/1     Running   0          13m   10.244.116.6    vms63   <none>           <none>
web1-6464d54bd7-xfgth   1/1     Running   0          13m   10.244.196.40   vms62   <none>           <none>
[root@vms61 chap9-svc]# kubectl exec -it web1-6464d54bd7-dt9qt -- bash
root@web1-6464d54bd7-dt9qt:/# echo 11111 > /usr/share/nginx/html/index.html 
root@web1-6464d54bd7-dt9qt:/# exit
exit
[root@vms61 chap9-svc]# kubectl exec -it web1-6464d54bd7-vtkwz -- bash
root@web1-6464d54bd7-vtkwz:/# echo 22222 > /usr/share/nginx/html/index.html
root@web1-6464d54bd7-vtkwz:/# exit
exit
[root@vms61 chap9-svc]# kubectl exec -it web1-6464d54bd7-xfgth -- bash
root@web1-6464d54bd7-xfgth:/# echo 33333 > /usr/share/nginx/html/index.html
root@web1-6464d54bd7-xfgth:/# exit
exit
[root@vms61 chap9-svc]# kubectl get svc
NAME   TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)   AGE
svc1   ClusterIP   10.107.89.230   <none>        80/TCP    14m
[root@vms61 chap9-svc]# curl -s 10.107.89.230
33333
[root@vms61 chap9-svc]# curl -s 10.107.89.230
22222
[root@vms61 chap9-svc]# curl -s 10.107.89.230
11111
[root@vms61 chap9-svc]# curl -s 10.107.89.230
11111
[root@vms61 chap9-svc]# curl -s 10.107.89.230
33333
[root@vms61 chap9-svc]# curl -s 10.107.89.230
11111
[root@vms61 chap9-svc]# curl -s 10.107.89.230
33333
[root@vms61 chap9-svc]# curl -s 10.107.89.230
33333
[root@vms61 chap9-svc]# curl -s 10.107.89.230
33333
[root@vms61 chap9-svc]# curl -s 10.107.89.230
11111
[root@vms61 chap9-svc]# curl -s 10.107.89.230
22222
[root@vms61 chap9-svc]# curl -s 10.107.89.230
22222

如果我现在有一个服务svc1，找出此服务后端到底有多少个pod

根据selector这个下的标签来定位（不是labels）

[root@vms61 chap9-svc]# kubectl describe svc svc1
Name:              svc1
Namespace:         chap9-svc
Labels:            aa=bb
Annotations:       <none>
Selector:          app2=web2
Type:              ClusterIP
IP:                10.105.180.153
Port:              <unset>  80/TCP
TargetPort:        80/TCP
Endpoints:         10.244.116.6:80,10.244.196.38:80,10.244.196.40:80
Session Affinity:  None
Events:            <none>
[root@vms61 chap9-svc]# kubectl get pods -l app2=web2
NAME                    READY   STATUS    RESTARTS   AGE
web1-6464d54bd7-dt9qt   1/1     Running   0          27m
web1-6464d54bd7-vtkwz   1/1     Running   0          27m
web1-6464d54bd7-xfgth   1/1     Running   0          27m

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