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
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| 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}"
}
}
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| 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'
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添加路由配置
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| spring:
cloud:
kubernetes:
discovery:
catalogServicesWatchDelay: 5000
client:
master-url: https://kubernetes.docker.internal:6443
ca-cert-data: xxx
namespace: default
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| 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: '*'
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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
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| 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
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| kubectl apply -f api.yaml
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部署 Gateway
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| 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
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| kubectl apply -f gateway.yaml
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测试
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| http get localhost:30080/actuator/gateway/routes
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| http get localhost:30080/api/hello
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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
启动多个 API 服务实例
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| kubectl scale --replicas=2 deploy/api
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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
