1 前言

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Kubernetes有專門的ConfigMap和Secret來管理配置，但它也有一些局限性省撑，所以還是希望通過Spring Cloud Config來管理赌蔑。在Kubernetes上面的微服務(wù)系統(tǒng)會有所不同，我們來探索一下如何整合Spring Cloud Kubernetes來做配置管理竟秫。

整體方案與《使用Spring Cloud Config統(tǒng)一管理配置娃惯，別再到處放配置文件了》差不多，只是引入Spring Cloud Kubernetes來使用Kubernetes的服務(wù)發(fā)現(xiàn)肥败，而不使用Eureka等趾浅。

2 服務(wù)端

引入依賴：

<dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-config-server</artifactId>
  <version>2.2.0.RELEASE</version>
</dependency>
<dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-starter-kubernetes</artifactId>
</dependency>

服務(wù)端啟動類如下：

package com.pkslow.config;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.config.server.EnableConfigServer;

@SpringBootApplication
@EnableConfigServer
@EnableDiscoveryClient
public class ConfigServerK8s {
    public static void main(String[] args) {
        SpringApplication.run(ConfigServerK8s.class, args);
    }
}

服務(wù)端的application.properties配置如下：

server.port=8888
spring.application.name=config-server-k8s
spring.cloud.config.server.git.uri=https://github.com/pkslow/pkslow-config
spring.cloud.config.server.git.username=admin@pkslow.com
spring.cloud.config.server.git.password=***
spring.cloud.config.server.git.default-label=master
spring.cloud.config.server.git.search-paths=demo

這里的應(yīng)用名字為config-server-k8s，后續(xù)部署到k8s也是用這個名字馒稍。

k8s的資源定義文件如下：

apiVersion: apps/v1
kind: Deployment
metadata:
  name: config-server-k8s-deployment
spec:
  selector:
    matchLabels:
      app: config-server-k8s
  replicas: 1
  template:
    metadata:
      labels:
        app: config-server-k8s
    spec:
      containers:
        - name: config-server-k8s
          image: pkslow/config-server-k8s:1.0-SNAPSHOT
          ports:
            - containerPort: 8888

---
apiVersion: v1
kind: Service
metadata:
  labels:
    app: config-server-k8s
  name: config-server-k8s
spec:
  ports:
    - port: 8888
      name: config-server-k8s
      protocol: TCP
      targetPort: 8888
  selector:
    app: config-server-k8s
  type: ClusterIP
---
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: config-server-k8s
  annotations:
    kubernetes.io/ingress.class: nginx
spec:
  rules:
    - http:
        paths:
          - path: /
            backend:
              serviceName: config-server-k8s
              servicePort: 8888
      host: config-server-k8s.localhost

保持Service名字統(tǒng)一為config-server-k8s皿哨。

3 客戶端

引入依賴：

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-starter-kubernetes</artifactId>
</dependency>
<dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-starter-config</artifactId>
</dependency>
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-actuator</artifactId>
</dependency>

spring-cloud-starter-kubernetes為服務(wù)發(fā)現(xiàn)；

spring-cloud-starter-config作為配置客戶端纽谒；

spring-boot-starter-actuator提供EndPoint來刷新配置证膨。

啟動類為：

package com.pkslow.config;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@SpringBootApplication
@EnableDiscoveryClient
public class ConfigClientK8s {
    public static void main(String[] args) {
        SpringApplication.run(ConfigClientK8s.class, args);
    }
}

配置文件bootstrap.properties如下：

server.port=8080

# 服務(wù)名
spring.application.name=config-client-k8s

# 讀取配置時的profile
spring.profiles.active=dev
# 讀取配置時的代碼分支
spring.cloud.config.label=release

# 開放刷新接口
management.endpoints.web.exposure.include=*
management.endpoint.health.show-details=always

# 通過服務(wù)名找到配置服務(wù)器
spring.cloud.config.discovery.enabled=true
spring.cloud.config.discovery.service-id=config-server-k8s

展示配置結(jié)果的Web服務(wù)：

package com.pkslow.config;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.cloud.context.config.annotation.RefreshScope;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.HashMap;
import java.util.Map;

@RefreshScope
@RestController
public class PkslowController {
    @Value("${pkslow.age:0}")
    private Integer age;

    @Value("${pkslow.email:null}")
    private String email;

    @Value("${pkslow.webSite:null}")
    private String webSite;

    @GetMapping("/pkslow")
    public Map<String, String> getConfig() {
        Map<String, String> map = new HashMap<>();
        map.put("age", age.toString());
        map.put("email", email);
        map.put("webSite", webSite);
        return map;
    }
}

客戶端的k8s文件：

apiVersion: apps/v1
kind: Deployment
metadata:
  name: config-client-k8s-deployment
spec:
  selector:
    matchLabels:
      app: config-client-k8s
  replicas: 1
  template:
    metadata:
      labels:
        app: config-client-k8s
    spec:
      containers:
        - name: config-client-k8s
          image: pkslow/config-client-k8s:1.0-SNAPSHOT
          ports:
            - containerPort: 8080

---
apiVersion: v1
kind: Service
metadata:
  labels:
    app: config-client-k8s
  name: config-client-k8s
spec:
  ports:
    - port: 8080
      name: config-client-k8s
      protocol: TCP
      targetPort: 8080
  selector:
    app: config-client-k8s
  type: ClusterIP
---
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: config-client-k8s
  annotations:
    kubernetes.io/ingress.class: nginx
spec:
  rules:
    - http:
        paths:
          - path: /
            backend:
              serviceName: config-client-k8s
              servicePort: 8080
      host: config-client-k8s.localhost

注意Service名字為config-client-k8s。

4 部署與測試

總結(jié)一下鼓黔，服務(wù)端主要做了兩件事：

（1）提供配置服務(wù)央勒，從Github中讀取配置；

（2）把自己注冊到Kubernetes中去澳化，以讓客戶端發(fā)現(xiàn)并讀取配置崔步。

客戶端主要做了件事：

（1）作為配置客戶端，從服務(wù)端讀配置缎谷；

（2）把自己注冊到Kubernetes中去刷晋，讓服務(wù)端可以訪問；

（3）提供刷新配置的功能給外界調(diào)用慎陵。

根據(jù)客戶端的名字眼虱、配置的label和profile，客戶端便會讀取release分支的配置文件config-client-k8s-dev.properties的內(nèi)部席纽。

訪問http://config-client-k8s.localhost/pkslow結(jié)果如下：

如果修改了配置信息捏悬，客戶端不能及時生效，需要通過發(fā)送POST請求到http://config-client-k8s.localhost/actuator/refresh润梯，這點(diǎn)不再贅述过牙。

5 服務(wù)端統(tǒng)一刷新

如果改了大量配置甥厦，或者基礎(chǔ)配置，想讓所有客戶端生效怎么辦寇钉？總不能一個個去刷新刀疙？而且在客戶端有多個Pod需要LoadBalance的情況下，無法確保每個Java應(yīng)用都能刷新到扫倡。

所以讓服務(wù)去讀取所有相關(guān)的客戶端谦秧，并刷新。實(shí)現(xiàn)很簡單撵溃，直接新增一個RefreshController就可以了：

package com.pkslow.config;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

@RestController
public class RefreshController {
    @Autowired
    private DiscoveryClient discoveryClient;

    private RestTemplate rest = new RestTemplate();

    @GetMapping("/refresh")
    public Map<String, String> refresh() {

        Map<String, String> result = new HashMap<>();
        List<String> services = discoveryClient.getServices();
        result.put("Basic Info", "Total services in k8s:" + services.size());

        services.stream()
                .filter(s -> (!"config-server-k8s".equals(s)) && s.startsWith("config-client"))
                .forEach(service -> {
                    List<ServiceInstance> instances = discoveryClient.getInstances(service);

                    instances.forEach(instance -> {
                        String url = "http://" + instance.getHost() + ":" + instance.getPort() + "/actuator/refresh";

                        try {
                            HttpHeaders headers = new HttpHeaders();
                            headers.setContentType(MediaType.APPLICATION_JSON);
                            HttpEntity<String> entity = new HttpEntity<>(null, headers);
                            ResponseEntity<String> response = rest.postForEntity(url, entity, String.class);
                            result.put(service + " " + url, response.getStatusCode().getReasonPhrase());
                        } catch (Exception e) {
                            result.put(service + " " + url, e.getMessage());
                        }
                    });
                });

        return result;
    }
}

注意上面的過濾邏輯疚鲤，因?yàn)椴皇撬?code>Service都可以、都需要refresh缘挑，具體邏輯看業(yè)務(wù)集歇。

請求http://config-server-k8s.localhost/refresh結(jié)果如下（把客戶端的replicas設(shè)置成了3）：

{
  "config-client-k8s http://10.1.0.126:8080/actuator/refresh": "OK",
  "config-client-k8s http://10.1.0.125:8080/actuator/refresh": "OK",
  "Basic Info": "Total services in k8s:7",
  "config-client-k8s http://10.1.0.122:8080/actuator/refresh": "OK"
}

注：可能會遇到權(quán)限不足的問題，創(chuàng)建一個對應(yīng)的Kubernetes ServiceAccount即可语淘，不清楚可以參考：把Spring Cloud Data Flow部署在Kubernetes上诲宇，再跑個任務(wù)試試

客戶端其實(shí)不一定需要引入DiscoveryService，如果不通過Server的ServiceId來尋找地址惶翻，而是直接配置服務(wù)端地址spring.cloud.config.uri焕窝。但服務(wù)端是需要的，因?yàn)橐@取客戶端的信息來實(shí)現(xiàn)統(tǒng)一reload维贺。