Kubernetes 简明教程

Kubernetes - Service

服务可以定义为 pod 的逻辑集合。它可以定义为 pod 上的抽象，它提供一个单个 IP 地址和 DNS 名称，可以通过它访问 pod。使用服务，非常容易管理负载均衡配置。它帮助 pod 非常容易地扩展。

A service can be defined as a logical set of pods. It can be defined as an abstraction on the top of the pod which provides a single IP address and DNS name by which pods can be accessed. With Service, it is very easy to manage load balancing configuration. It helps pods to scale very easily.

在 Kubernetes 中，服务是一个 REST 对象，它的定义可以发布到 Kubernetes master 上的 Kubernetes apiServer 以创建一个新实例。

A service is a REST object in Kubernetes whose definition can be posted to Kubernetes apiServer on the Kubernetes master to create a new instance.

Service without Selector

apiVersion: v1
kind: Service
metadata:
   name: Tutorial_point_service
spec:
   ports:
   - port: 8080
   targetPort: 31999

上面的配置将创建一个名为 Tutorial_point_service 的服务。

The above configuration will create a service with the name Tutorial_point_service.

Service Config File with Selector

apiVersion: v1
kind: Service
metadata:
   name: Tutorial_point_service
spec:
   selector:
      application: "My Application" -------------------> (Selector)
   ports:
   - port: 8080
   targetPort: 31999

在这个示例中，我们有一个选择器；所以为了传输流量，我们需要手动创建一个端点。

In this example, we have a selector; so in order to transfer traffic, we need to create an endpoint manually.

apiVersion: v1
kind: Endpoints
metadata:
   name: Tutorial_point_service
subnets:
   address:
      "ip": "192.168.168.40" -------------------> (Selector)
   ports:
      - port: 8080

在上面的代码中，我们创建了一个端点，它将路由流量到定义为“192.168.168.40:8080”的端点。

In the above code, we have created an endpoint which will route the traffic to the endpoint defined as “192.168.168.40:8080”.

Multi-Port Service Creation

apiVersion: v1
kind: Service
metadata:
   name: Tutorial_point_service
spec:
   selector:
      application: “My Application” -------------------> (Selector)
   ClusterIP: 10.3.0.12
   ports:
      -name: http
      protocol: TCP
      port: 80
      targetPort: 31999
   -name:https
      Protocol: TCP
      Port: 443
      targetPort: 31998

Types of Services

ClusterIP − 这有助于在集群内限制服务。它在定义的 Kubernetes 集群内公开该服务。

ClusterIP − This helps in restricting the service within the cluster. It exposes the service within the defined Kubernetes cluster.

spec:
   type: NodePort
   ports:
   - port: 8080
      nodePort: 31999
      name: NodeportService

NodePort − 它将在已部署节点上的静态端口公开服务。一个服务， NodePort 服务将路由到的服务自动创建。使用 NodeIP:nodePort 可以从集群外访问该服务。

NodePort − It will expose the service on a static port on the deployed node. A ClusterIP service, to which NodePort service will route, is automatically created. The service can be accessed from outside the cluster using the NodeIP:nodePort.

spec:
   ports:
   - port: 8080
      nodePort: 31999
      name: NodeportService
      clusterIP: 10.20.30.40

Load Balancer − 它使用云服务商的负载均衡器。 NodePort 和 ClusterIP 服务自动创建，外部负载均衡器将路由到这些服务。

Load Balancer − It uses cloud providers’ load balancer. NodePort and ClusterIP services are created automatically to which the external load balancer will route.

一个完整服务 yaml 文件，其服务类型为节点端口。尝试自己创建一个。

A full service yaml file with service type as Node Port. Try to create one yourself.

apiVersion: v1
kind: Service
metadata:
   name: appname
   labels:
      k8s-app: appname
spec:
   type: NodePort
   ports:
   - port: 8080
      nodePort: 31999
      name: omninginx
   selector:
      k8s-app: appname
      component: nginx
      env: env_name