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k8s中Service(svc)的类型使用

前言

k8s中svc有三种类型，分别为ClusterIP、NodePort、LoadBalancer

作用
  • 能够解耦前端和后端的关联
类型用途及其使用

部署的应用为无状态应用服务，参考k8s中部署无状态(deployment)服务，此技术文档以此参考，通过deployment控制器部署了Pod资源，在此基础上，去实现service的类型应用实现

ClusterIP

  • 概述
    分配一个内部集群IP地址，只能在集群内部访问(同Namespace内的Pod)，默认ServiceType，ClusterIP模式的Service默认提供的，就是一个Pod的稳定的IP地址，即VIP，访问地址: :

  • yaml文本示例

cat > ng-svc-clusterip.yaml <<-EOF
apiVersion: v1
kind: Service
metadata:name: nginx-clusteripnamespace: default
spec:selector:app: nginx-dev	# 为Pod资源的app键值type: ClusterIPports:- protocol: TCPtargetPort: 80port: 80
EOF
  • 查看其svc相关信息
]# kubectl apply -f ng-svc-clusterip.yaml
]# kubectl get svc -n default | grep nginx
nginx--clusterip              ClusterIP      172.21.6.109    <none>                                        80/TCP               18m
  • 访问其应用服务
]# curl 172.21.6.109
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>body {width: 35em;margin: 0 auto;font-family: Tahoma, Verdana, Arial, sans-serif;}
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p><p>For online documentation and support please refer to
<a href="/">nginx</a>.<br/>
Commercial support is available at
<a href="/">nginx</a>.</p><p><em>Thank you for using nginx.</em></p>
</body>
</html>
NodePort

  • 概述
    分配一个内部集群IP地址，并在每个节点上启用一个端口来暴露服务，可以在集群内部访问，访问地址: :

  • 要点
    类型缺陷

a. 端口容器冲突
b. NodePort属于四层，不能做七层的事，比如根据域名/url进行转发
c. 不能统一入口
  • yaml文本示例
cat > ng-svc-nodeport.yaml <<-EOF
apiVersion: v1
kind: Service
metadata:name: nginx-nodeportnamespace: default
spec:selector:app: nginx-devtype: NodePortports:- protocol: TCPtargetPort: 80port: 8020
EOF
  • 查看其svc相关信息
]# kubectl apply -f ng-svc-nodeport.yaml
]# kubectl get svc -n default | grep nginx
nginx-nodeport          NodePort       172.21.12.177   <none>                                        8020:30076/TCP       48m

其中8020:30076的8020为内部集群端口，而30076为公网ip/NodeIP端口

  • 访问其应用服务

a.内部集群访问

]# curl 172.21.12.177:8020
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>body {width: 35em;margin: 0 auto;font-family: Tahoma, Verdana, Arial, sans-serif;}
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p><p>For online documentation and support please refer to
<a href="/">nginx</a>.<br/>
Commercial support is available at
<a href="/">nginx</a>.</p><p><em>Thank you for using nginx.</em></p>
</body>
</html>

b.通过公网ip/NodeIP访问

]# curl 公网ip/NodeIP:30076
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>body {width: 35em;margin: 0 auto;font-family: Tahoma, Verdana, Arial, sans-serif;}
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p><p>For online documentation and support please refer to
<a href="/">nginx</a>.<br/>
Commercial support is available at
<a href="/">nginx</a>.</p><p><em>Thank you for using nginx.</em></p>
</body>
</html>
LoadBalancer

  • 概述
    分配一个内部集群IP地址，并在每个节点上启用一个端口来暴露服务，除此之外，k8s会请求底层云平台上的负载均衡器，将每个Node ([NodeIP]:[NodePort])作为后端添加进去

  • yaml文本示例

cat > ng-svc-lb.yaml <<-EOF
apiVersion: v1
kind: Service
metadata:annotations:service.beta.kubernetes.io/alibaba-cloud-loadbalancer-id: "lb-wxxx"		# 负载均衡器的实例id值service.beta.kubernetes.io/alibaba-cloud-loadbalancer-force-override-listeners: "true"name: nginx-lbnamespace: default
spec:selector:app: nginx-devtype: LoadBalancerports:- protocol: TCPtargetPort: 80port: 8030
  • 查看其svc相关信息
]# kubectl apply -f ng-svc-lb.yaml
]# kubectl get svc -n default | grep nginx
nginx-lb                LoadBalancer   172.21.11.211   120.76.70.149                                  8030:30636/TCP       54s

其中8030:30076的8030为内部集群端口，而30636为公网ip/NodeIP端口

  • 访问其应用服务

a.内部集群访问

]# curl 172.21.11.211:8030
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>body {width: 35em;margin: 0 auto;font-family: Tahoma, Verdana, Arial, sans-serif;}
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p><p>For online documentation and support please refer to
<a href="/">nginx</a>.<br/>
Commercial support is available at
<a href="/">nginx</a>.</p><p><em>Thank you for using nginx.</em></p>
</body>
</html>

b.通过负载均衡器IP访问

]# curl 120.76.70.149:8030
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>body {width: 35em;margin: 0 auto;font-family: Tahoma, Verdana, Arial, sans-serif;}
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p><p>For online documentation and support please refer to
<a href="/">nginx</a>.<br/>
Commercial support is available at
<a href="/">nginx</a>.</p><p><em>Thank you for using nginx.</em></p>
</body>
</html>

c.通过公网ip/NodeIP访问

]# curl 公网ip/NodeIP:30636
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>body {width: 35em;margin: 0 auto;font-family: Tahoma, Verdana, Arial, sans-serif;}
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p><p>For online documentation and support please refer to
<a href="/">nginx</a>.<br/>
Commercial support is available at
<a href="/">nginx</a>.</p><p><em>Thank you for using nginx.</em></p>
</body>
</html>
结语

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本文标签： k8s中Service(svc)的类型使用

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