k8s资源之service

发布一个k8s部署视频：https://edu.csdn.net/course/detail/26967

课程内容：各种k8s部署方式。包括minikube部署，kubeadm部署，kubeasz部署，rancher部署，k3s部署。包括开发测试环境部署k8s，和生产环境部署k8s。
————————————————

•在k8s集群中，service是一个抽象概念，它通过一个虚拟的IP映射指定的端口，将代理客户端发来的请求转到后端一组pod中的一个上。这是个神马意思呢？pod中的容器经常在不停地销毁和重建，因此pod的IP会不停的改变，这时候客户端就没法访问到pod了，现在有了service作为客户端和pod的中间层，它在这里抽象出一个虚拟IP，然后集群内部都可以通过这个虚拟IP访问到具体的pod。

常用命令：

•kubectl get svc

•kubectl label svc ServiceName type=s1

•kubectl label svc ServiceName type-

•kubectl get svc -l type=s1

•kubectl describe svc ServiceName

•kubectl edit svc ServiceName

•Kubectl delete svc ServiceName

•Kubectl delete svc -l type=s1

•Kubectl delete svc –all –n namespace

•Kubectl annotate svc ServiceName type=s1

•Kubectl annotate svc ServiceName type-

•kubectl patch service nginx-clusterip-svc -p '{"metadata":{"labels":{"aa":"bb"}}}‘

•kubectl get svc nginx-clusterip-svc -o yaml

•kubectl get svc nginx-clusterip-svc -o json

•kubectl get svc -o wide

 

Service的工作方式：

•Userspace方式

•iptables模型

• ipvs模型

Userspace模式：

Client Pod要访问Server Pod时,它先将请求发给本机内核空间中的service规则，由它再将请求,转给监听在指定套接字上的kube-proxy，kube-proxy处理完请求，并分发请求到指定Server Pod后,再将请求递交给内核空间中的service,由service将请求转给指定的clinet Pod。
　　由于其需要来回在用户空间和内核空间交互通信，因此效率很差

iptables：

直接由内核中的iptables规则，接受Client Pod的请求，并处理完成后，直接转发给指定ServerPod

ipvs：

接有内核中的ipvs规则来接受Client Pod请求，并处理该请求,再有内核封包后，直接发给指定的Server Pod

以上不论哪种，kube-proxy都通过watch的方式监控着kube-APIServer写入etcd中关于Pod的最新状态信息,它一旦检查到一个Pod资源被删除了 或 新建，它将立即将这些变化，反应再iptables 或 ipvs规则中，以便iptables和ipvs在调度Clinet Pod请求到Server Pod时，不会出现Server Pod不存在的情况

启用方法：

以service方式启动kube-proxy

•–proxy-mode=userspace

•–proxy-mode=iptables

•–proxy-mode=ipvs

以pod方式启动kube-proxy

kubectl edit cm kube-proxy -n kube-system

mode: “ipvs” or iptables or userspace

之后重启各个节点上的kube-proxy pod

Service类型：

•ExternalName

•ClusterIP

•NodePort

•LoadBalancer

clusterip：

[root@master01 service]# cat nginx-clusterIp-svc.yaml 
apiVersion: v1
kind: Service
metadata:
  name: nginx-clusterip-svc
spec:
 selector:  
   app: nginx
 type: ClusterIP
 ports:
 -  name: http
    port: 8000      
    targetPort: 80

[root@master01 service]# cat nginx-clusterIp-svc-assign-address.yaml 
apiVersion: v1
kind: Service
metadata:
  name: nginx-clusterip-svc-with-ip
spec:
 selector:  
   app: nginx
 clusterIP: 10.68.100.100
 type: ClusterIP
 ports:
 -  name: http
    port: 8000      
    targetPort: 80

[root@master01 service]# cat nginx-clusterIp-svc-headless.yaml 
apiVersion: v1
kind: Service
metadata:
  name: nginx-clusterip-svc-headless
spec:
 selector:  
   app: nginx
 type: ClusterIP
 clusterIP: None
 ports:
 -  name: http
    port: 8000      
    targetPort: 80

[root@master01 service]# cat nginx-clusterIp-svc-with-externalip.yaml 
apiVersion: v1
kind: Service
metadata:
  name: nginx-clusterip-svc-with-externalip
spec:
 selector:  
   app: nginx
 type: ClusterIP
 externalIPs: 
 - 192.168.198.111
 ports:
 -  name: http
    port: 8000      
    targetPort: 80

exteranlName：

[root@master01 service]# cat nginx-exteranlName-svc.yaml 
apiVersion: v1
kind: Service
metadata:
  name: nginx-externalname-svc
spec:
 externalName: www.baidu.com
 type: ExternalName

[root@master01 service]# cat nginx-exteranlName-svc-with-externalips.yaml 
apiVersion: v1
kind: Service
metadata:
  name: nginx-externalname-svc-with-externalips
spec:
 externalName: www.baidu.com
 type: ExternalName
 externalIPs:
 - 192.168.198.16
 - 192.168.198.17

loadblancer：

[root@master01 service]# cat nginx-loadblancer-svc.yaml 
apiVersion: v1
kind: Service
metadata:
  name: nginx-loadblancer-svc
spec:
 selector:  
   app: nginx
 type: LoadBalancer
 loadBalancerIP: 1.2.3.4
 ports:
 -  name: http
    port: 8000      
    targetPort: 80

[root@master01 service]# cat nginx-loadblancer-svc-without-ip.yaml 
apiVersion: v1
kind: Service
metadata:
  name: nginx-loadblancer-withoutip-svc
spec:
 selector:  
   app: nginx
 type: LoadBalancer
 ports:
 -  name: http
    port: 8000      
    targetPort: 80

[root@master01 service]# cat nginx-loadblancer-svc-with-externalips.yaml 
apiVersion: v1
kind: Service
metadata:
  name: nginx-loadblancer-with-externalips
spec:
 selector:  
   app: nginx
 type: LoadBalancer
 externalIPs:
 - 192.168.198.13
 - 192.168.198.14
 ports:
 -  name: http
    port: 8000      
    targetPort: 80

nodePort：

[root@master01 service]# cat nginx-nodePort-svc.yaml 
apiVersion: v1
kind: Service
metadata:
  name: nginx-nodeport-svc
spec:
 selector:  
   app: nginx
 type: NodePort
 ports:
 -  name: http
    port: 8000      
    targetPort: 80

[root@master01 service]# cat nginx-nodePort-svc-with-port.yaml 
apiVersion: v1
kind: Service
metadata:
  name: nginx-nodeport-svc-with-port
spec:
 selector:  
   app: nginx
 type: NodePort
 ports:
 -  name: http
    port: 8000      
    targetPort: 80
    nodePort: 31000

[root@master01 service]# cat nginx-nodePort-svc-with-externalip.yaml 
apiVersion: v1
kind: Service
metadata:
  name: nginx-nodeport-svc-with-externalips
spec:
 selector:  
   app: nginx
 type: NodePort
 externalIPs:
 - 192.168.198.10
 - 192.168.198.11
 ports:
 -  name: http
    port: 8000      
    targetPort: 80

sessionaffinity：

[root@master01 service]# cat nginx-clusterIp-svc-sessionAffinity.yaml 
apiVersion: v1
kind: Service
metadata:
  name: nginx-clusterip-svc-with-sessionaffinity
spec:
 selector:  
   app: nginx
 type: ClusterIP
 sessionAffinity: ClientIP
 ports:
 -  name: http
    port: 8000      
    targetPort: 80

[root@master01 service]# cat nginx-nodePort-svc-with-sessionaffinity.yal 
apiVersion: v1
kind: Service
metadata:
  name: nginx-nodeport-svc-with-sessionaffinity
spec:
 selector:  
   app: nginx
 type: NodePort
 sessionAffinity: ClientIP
 ports:
 -  name: http
    port: 8000      
    targetPort: 80

[root@master01 service]# cat nginx-loadblancer-svc-with-sessionaffinity.yaml 
apiVersion: v1
kind: Service
metadata:
  name: nginx-loadblancer-with-sessionaffinity
spec:
 selector:  
   app: nginx
 type: LoadBalancer
 sessionAffinity: ClientIP
 ports:
 -  name: http
    port: 8000      
    targetPort: 80

[root@master01 service]# cat nginx-exteranlName-svc-with-sessionaffinity.yaml 
apiVersion: v1
kind: Service
metadata:
  name: nginx-externalname-svc-with-sessionaffinity
spec:
 externalName: www.baidu.com
 type: ExternalName
 sessionAffinity: ClientIP

externalTrafficPolicy：

•LoadBalancer and Nodeport type services

如果服务需要将外部流量路由到 本地节点或者集群级别的端点，即service type 为LoadBalancer或NodePort，那么需要指明该参数。存在两种选项：”Cluster”（默认）和 “Local”。 “Cluster” 隐藏源 IP 地址，可能会导致第二跳（second hop）到其他节点，但是全局负载效果较好。”Local” 保留客户端源 IP 地址，避免 LoadBalancer 和 NodePort 类型服务的第二跳，但是可能会导致负载不平衡

root@master01 service]# cat nginx-nodePort-svc-externalTrafficPolicy.yaml 
apiVersion: v1
kind: Service
metadata:
  name: nginx-nodeport-svc-externaltrafficpolicy
spec:
 selector:  
   app: nginx
 type: NodePort
 externalTrafficPolicy: Local
 ports:
 -  name: http
    port: 8000      
    targetPort: 80

[root@master01 service]# cat nginx-loadblancer-svc-externalTrafficPolicy.yaml 
apiVersion: v1
kind: Service
metadata:
  name: nginx-loadblancer-svc-externaltrafficpolicy
spec:
 selector:  
   app: nginx
 type: LoadBalancer
 externalTrafficPolicy: Local
 ports:
 -  name: http
    port: 8000      
    targetPort: 80

healthCheckNodePort：

只有当类型被设置成 “LoadBalancer” 并且 externalTrafficPolicy 被设置成 “Local” 时，才会生效

ipFamily：

[root@master01 service]# cat nginx-clusterIp-svc-ipFamily.yaml 
apiVersion: v1
kind: Service
metadata:
  name: nginx-clusterip-svc-ipfamily
spec:
 selector:  
   app: nginx
 type: ClusterIP
 ipFamily: IPv6
 ports:
 -  name: http
    port: 8000      
    targetPort: 80

•To enable IPv4/IPv6 dual-stack, enable the IPv6DualStack feature gate for the relevant components of your cluster, and set dual-stack cluster network assignments:

•kube-controller-manager:

–--feature-gates="IPv6DualStack=true"

–--cluster-cidr=<IPv4 CIDR>,<IPv6 CIDR> eg. --cluster-cidr=10.244.0.0/16,fc00::/24

–--service-cluster-ip-range=<IPv4 CIDR>,<IPv6 CIDR>

–--node-cidr-mask-size-ipv4|--node-cidr-mask-size-ipv6 defaults to /24 for IPv4 and /64 for IPv6

•kubelet:

–--feature-gates="IPv6DualStack=true"

•kube-proxy:

–--proxy-mode=ipvs

–--cluster-cidrs=<IPv4 CIDR>,<IPv6 CIDR>

–--feature-gates="IPv6DualStack=true"

 

 

loadBalancerSourceRanges：

•This feature is currently supported on Google Compute Engine, Google Kubernetes Engine, AWS Elastic Kubernetes Service, Azure Kubernetes Service, and IBM Cloud Kubernetes Service.

 

sessionAffinityConfig：

[root@master01 service]# cat nginx-clusterIp-svc-sessionAffinityConfig.yaml 
apiVersion: v1
kind: Service
metadata:
  name: nginx-clusterip-svc-sessionaffinityconfig
spec:
 selector:  
   app: nginx
 type: ClusterIP
 sessionAffinity: ClientIP
 sessionAffinityConfig:
   clientIP:
     timeoutSeconds: 2
 ports:
 -  name: http
    port: 8000      
    targetPort: 80

 

 

 

 

 

 

 

来源：CSDN

作者：hxpjava1

链接：https://blog.csdn.net/hxpjava1/article/details/103663940