K8S基础 - 06Service

K8S基础 - 06Service

一、介绍

• node network, pod network, cluster network
• service: virtual IP, CoreDNS, kube-dns
• api-service <-- watch --> kube-proxy
• 工作模式： userspace, iptables, ipvs
  • userspace: 1.1-
  • iptables: 1.10-
  • ipvs: 1.11+
• 类型：ExternalName, ClusterIP, NodePort, LoadBalance

 

 

 

[root@k8s-master ~]# kubectl explain pod.spec

   hostIPC	<boolean>
     Use the host's ipc namespace. Optional: Default to false.

   hostNetwork	<boolean>
     Host networking requested for this pod. Use the host's network namespace.
     If this option is set, the ports that will be used must be specified.
     Default to false.

   hostPID	<boolean>
     Use the host's pid namespace. Optional: Default to false.

　　

二、 Service

2.1 创建ClusterIP Service

[root@k8s-master ~]# cat svc-redis.yml 
apiVersion: v1
kind: Service
metadata:
  name: redis-demo
  namespace: default
spec:
  selector:
    app: redis
    role: logstor
  clusterIP: 10.98.98.98
  type: ClusterIP
  ports:
  - port: 6379
    targetPort: 6379

　　

[root@k8s-master ~]# kubectl apply -f svc-redis.yml 
service/redis-demo created

[root@k8s-master ~]# kubectl get svc
NAME                   TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
redis                  ClusterIP   10.99.58.88      <none>        6379/TCP       3d22h
redis-demo             ClusterIP   10.98.98.98      <none>        6379/TCP       24s
[root@k8s-master ~]# kubectl describe svc redis-demo
Name:              redis-demo
Namespace:         default
Labels:            <none>
Annotations:       <none>
Selector:          app=redis,role=logstor
Type:              ClusterIP
IP:                10.98.98.98
Port:              <unset>  6379/TCP
TargetPort:        6379/TCP
Endpoints:         10.244.2.80:6379
Session Affinity:  None
Events:            <none>
[root@k8s-master ~]# telnet 10.98.98.98 6379
Trying 10.98.98.98...
Connected to 10.98.98.98.
Escape character is '^]'.
^]
telnet> quit
Connection closed.

　　

2.2 创建NodePort Service

[root@k8s-master pod-k8s]# cat svc-mynginx.yaml 
apiVersion: v1
kind: Service
metadata:
  name: svc-mynginx
spec:
  type: NodePort
  selector:
    app: mynginx
  ports:
  - name: http
    nodePort: 30089
    port: 80
    targetPort: 80

　　

[root@k8s-master pod-k8s]# kubectl get svc
NAME          TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
kubernetes    ClusterIP   10.96.0.1        <none>        443/TCP        17d
svc-mynginx   NodePort    10.109.228.159   <none>        80:30089/TCP   31h

　　

[root@k8s-master pod-k8s]# while true; do curl http://192.168.6.33:30089/hostname.html; sleep 1; done
mynginx-app-bddc44777-pl9vj
mynginx-app-bddc44777-fx6gj
mynginx-app-bddc44777-p9lkh
mynginx-app-bddc44777-fx6gj
mynginx-app-bddc44777-pl9vj
mynginx-app-bddc44777-fx6gj
mynginx-app-bddc44777-p9lkh
mynginx-app-bddc44777-p9lkh
mynginx-app-bddc44777-pl9vj

2.3 设置会话亲和性

默认 sessionAffinity: None

[root@k8s-master ~]# kubectl patch svc svc-mynginx -p '{"spec":{"sessionAffinity":"ClientIP"}}'
service/svc-mynginx patched
[root@k8s-master ~]# while true; do curl http://192.168.6.33:30089/hostname.html; sleep 1; done
mynginx-app-bddc44777-pl9vj
mynginx-app-bddc44777-pl9vj
mynginx-app-bddc44777-pl9vj
mynginx-app-bddc44777-pl9vj

 

资源记录：SVC_NAME.NS_NAME.DOMAIN.LTD. 

svc.cluster.local.

redis.default.svc.cluster.local.　　

 

三、无头service

3.1 创建Service 

[root@k8s-master pod-k8s]# cat svc-mynginx-headless.yaml 
apiVersion: v1
kind: Service
metadata:
  name: svc-mynginx-headless
  namespace: default
spec:
  selector:
    app: mynginx
  clusterIP: "None"             # 不能使用""
  ports:
  - port: 80
    targetPort: 80

　　

[root@k8s-master ~]# kubectl apply -f svc-mynginx-headless.yaml 
service/svc-mynginx-headless created
[root@k8s-master ~]# kubectl get svc
NAME                   TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
kubernetes             ClusterIP   10.96.0.1        <none>        443/TCP        17d
svc-mynginx            NodePort    10.109.228.159   <none>        80:30089/TCP   31h
svc-mynginx-headless   ClusterIP   None             <none>        80/TCP         3s

　　

3.2 解析service

# 正常解析地址为Service的ClusterIP
[root@k8s-master ~]# dig -t -A svc-mynginx.default.svc.cluster.local @10.96.0.10
;; ANSWER SECTION:
svc-mynginx.default.svc.cluster.local. 30 IN A	10.109.228.159

[root@k8s-master ~]# dig -t -A svc-mynginx-headless.default.svc.cluster.local @10.96.0.10
;; ANSWER SECTION:
svc-mynginx-headless.default.svc.cluster.local.	30 IN A	10.244.2.26
svc-mynginx-headless.default.svc.cluster.local.	30 IN A	10.244.3.34
svc-mynginx-headless.default.svc.cluster.local.	30 IN A	10.244.1.27
[root@k8s-master ~]# kubectl get pods -l app=mynginx -o wide
NAME                          READY   STATUS    RESTARTS   AGE   IP            NODE                    NOMINATED NODE   READINESS GATES
mynginx-app-bddc44777-fx6gj   1/1     Running   1          31h   10.244.1.27   k8s-node31.bearpx.com   <none>           <none>
mynginx-app-bddc44777-p9lkh   1/1     Running   1          31h   10.244.3.34   k8s-node32.bearpx.com   <none>           <none>
mynginx-app-bddc44777-pl9vj   1/1     Running   1          31h   10.244.2.26   k8s-node33.bearpx.com   <none>           <none>