Spring Cloud Gateway 使用 Kubernetes 作为服务发现_spring cloud gateway kubernetes发现

Spring Cloud Gateway 使用 Kubernetes 作为服务发现

Spring Cloud Gateway 作为网关，通过用于执行一些通用逻辑后做请求转发，后端可能涉及到多个服务，每个服务又有多个实例，调用服务实例就需要动态的更新，可以通过注册中心来实现，如果部署在K8S集群中，可以直接使用K8S实现服务发现

应用

Gateway

添加依赖

• build.gradle

plugins {
    id 'org.springframework.boot' version '2.2.6.RELEASE'
    id 'io.spring.dependency-management' version '1.0.9.RELEASE'
    id 'java'
}

ext {
    set('springCloudVersion', "Hoxton.SR1")
    set('springKubernetesVersion', "1.1.2.RELEASE")
}

dependencies {
    implementation 'org.springframework.cloud:spring-cloud-starter-gateway'
    implementation 'org.springframework.cloud:spring-cloud-kubernetes-discovery'
    implementation 'org.springframework.boot:spring-boot-starter-actuator'
   
    testImplementation('org.springframework.boot:spring-boot-starter-test') {
        exclude group: 'org.junit.vintage', module: 'junit-vintage-engine'
    }
}

dependencyManagement {
    imports {
        mavenBom "org.springframework.cloud:spring-cloud-dependencies:${springCloudVersion}"
        mavenBom "org.springframework.cloud:spring-cloud-kubernetes-dependencies:${springKubernetesVersion}"
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27

• 如果是需要客户端实现负载均衡，依赖是

    implementation 'org.springframework.cloud:spring-cloud-starter-gateway'
    implementation 'org.springframework.cloud:spring-cloud-starter-kubernetes-all'
    implementation 'org.springframework.cloud:spring-cloud-starter-netflix-ribbon'
1
2
3

添加路由配置

• bootstrap.yaml

spring:
  cloud:
    kubernetes:
      discovery:
        catalogServicesWatchDelay: 5000
      client:
        master-url: https://kubernetes.docker.internal:6443
        ca-cert-data: xxx
        namespace: default
1
2
3
4
5
6
7
8
9

• applicaiton.yaml

spring:
  application.name: gateway
  cloud:
    gateway:
      discovery:
        locator:
          enabled: true
          url-expression: "'http://'+serviceId+':'+port"
          lower-case-service-id: true
          
management:
  endpoints:
    web:
      exposure:
        include: '*'          
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

配置 url-expression 目的是为了在转发的时候直接转发到 Kubernetes 中相应的 Service 上去，默认的表达式为 "'lb://'+serviceId"，这种适用于通过 Consul 或者 Eureka，最终是根据服务的IP和端口访问，spring-cloud-kubernetes没有实现com.netflix.loadbalancer.AbstractServerList，所以不会进行IP转换，最终是通过服务名称查找Service 实现调用，所以不需要负载均衡

• 如果是客户端实现负载均衡，则不需要指定"'http://'+serviceId+':'+port"

部署

通过 Gateway 调用后端的 API 应用，该应用提供 REST 接口

部署后端API应用

• api.yaml

apiVersion: v1
kind: Service
metadata:
  name: api
  namespace: default
  labels:
    app: api
spec:
  type: ClusterIP
  ports:
    - port: 8080
  selector:
    app: api

---

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: api
  name: api
  namespace: default
spec:
  replicas: 1
  selector:
    matchLabels:
      app: api
  template:
    metadata:
      labels:
        app: api
    spec:
      containers:
        - name: api
          image: registry.cn-qingdao.aliyuncs.com/hellowoodes/api:1.0.0
          imagePullPolicy: IfNotPresent
          ports:
            - containerPort: 8080
              name: http
              protocol: TCP
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41

• 部署 API 服务

kubectl apply -f api.yaml
1

部署 Gateway

• gateway.yaml

apiVersion: v1
kind: Service
metadata:
  name: gateway
  namespace: default
  labels:
    app: gateway
spec:
  type: NodePort
  ports:
    - port: 8080
      nodePort: 30080
  selector:
    app: gateway

---

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: gateway
  name: gateway
  namespace: default
spec:
  replicas: 1
  selector:
    matchLabels:
      app: gateway
  template:
    metadata:
      labels:
        app: gateway
    spec:
      containers:
        - name: gateway
          image: registry.cn-qingdao.aliyuncs.com/hellowoodes/api-gateway:1.0.6
          imagePullPolicy: IfNotPresent
          ports:
            - containerPort: 8080
              name: http
              protocol: TCP
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42

• 部署 gateway 服务

kubectl apply -f gateway.yaml
1

测试

• 查询所有路由

http get localhost:30080/actuator/gateway/routes
1

• 请求 API 服务接口

http get localhost:30080/api/hello
1

这里会根据 api这个path 查找名为 api的 Service，然后调用 http://api:8080/hello，这个接口返回hostname，也就是pod的名称

• 负载均衡

启动多个 API 服务实例

kubectl scale --replicas=2 deploy/api
1

待服务启动后多次调用http://localhost:30080/api/hello，返回的pod名称会变化，说明负载均衡生效

参考

• how-to-set-up-spring-cloud-gateway-application-so-it-can-use-the-service-discove
• spring-cloud-kubernetes-spring-cloud-gateway-unable-to-find-instance-for-k8s
• salaboy/s1p_gateway
• why use ribbon in k8s?How about clusterIp?
• spring-cloud-starter-consul-discovery depends on spring-cloud-starter-netflix-ribbon
• What’s causing: forbidden: User “system:anonymous” in some Cloud Providers