Server

• 如何加載

  • 核心接口是EnvironmentRepository，提供配置的讀取

  public interface EnvironmentRepository {
        Environment findOne(String application, String profile, String label);
    }
  

  • EnvironmentRepository有多種實(shí)現(xiàn)，基于JDBC、SVN、GIT等等
  • 默認(rèn)情況下，使用的是 MultipleJGitEnvironmentRepository(可以配置多個(gè)地址的GIT數(shù)據(jù)源)
  • ConfigServerAutoConfiguration -> EnvironmentRepositoryConfiguration -> DefaultRepositoryConfiguration

  @Configuration
    @ConditionalOnMissingBean(value = EnvironmentRepository.class)
    class DefaultRepositoryConfiguration {
        ...
        @Bean
        public MultipleJGitEnvironmentRepository defaultEnvironmentRepository(...) throws Exception {
            return gitEnvironmentRepositoryFactory.build(environmentProperties);
        }
    }
  

  • MultipleJGitEnvironmentRepository 代理遍歷每個(gè) JGitEnvironmentRepository， JGitEnvironmentRepository 下使用 NativeEnvironmentRepository 代理讀取本地文件。
  • AbstractScmEnvironmentRepository#findOne

  public synchronized Environment findOne(String application, String profile, String label) {
        NativeEnvironmentRepository delegate = new NativeEnvironmentRepository(getEnvironment(),
                new NativeEnvironmentProperties());
        Locations locations = getLocations(application, profile, label);
        delegate.setSearchLocations(locations.getLocations());
        Environment result = delegate.findOne(application, profile, "");
        ...
                getUri());
    }
  

• 其中g(shù)etLocations這部會(huì)從GIT遠(yuǎn)程倉庫同步到本地

• JGitEnvironmentRepository#getLocations -> JGitEnvironmentRepository.refresh

public String refresh(String label) {
       Git git = createGitClient();
       ...
       checkout(git, label);
       ...
       merge(git, label);
       ...
       resetHard(...)
       ...
}

• 配置文件加載優(yōu)先級順序（上面的覆蓋下面的）

• 具體的邏輯參考NativeEnvironmentRepository和ConfigFileApplicationListener

• 如何注入

  • ConfigServer本身也可以注入自己的讀取的配置，使得其他服務(wù)可以和ConfigServer配置在一起，比如Eureka
  • Config的自身注入在BootStrap階段
  • ConfigServerBootstrapConfiguration#LocalPropertySourceLocatorConfiguration

   @Configuration
    @ConditionalOnProperty("spring.cloud.config.server.bootstrap")
    public class ConfigServerBootstrapConfiguration {
        @Bean
        public EnvironmentRepositoryPropertySourceLocator environmentRepositoryPropertySourceLocator() {
            return new EnvironmentRepositoryPropertySourceLocator(this.repository, this.client.getName(),
                    this.client.getProfile(), getDefaultLabel());
        }
    }
  

  • EnvironmentRepositoryPropertySourceLocator會(huì)調(diào)用EnvironmentRepository獲取配置

  public class EnvironmentRepositoryPropertySourceLocator implements PropertySourceLocator{
        @Override
        public PropertySource<?> locate(Environment environment) {
            CompositePropertySource composite = new CompositePropertySource("configService");
            for (PropertySource source : environmentRepository.findOne(name, profiles, label)
                    .getPropertySources()) {
                composite.addPropertySource(...);
            }
            return composite;
        }
  }
  

  • PropertySourceBootstrapConfiguration#init負(fù)責(zé)所有BootStrap配置的加載，所有實(shí)現(xiàn)PropertySourceLocator接口的服務(wù)都會(huì)被調(diào)用

  CompositePropertySource composite = new CompositePropertySource(
                BOOTSTRAP_PROPERTY_SOURCE_NAME);
    for (PropertySourceLocator locator : this.propertySourceLocators) {
        PropertySource<?> source = locator.locate(environment);
        composite.addPropertySource(source);
    }
  

Client

• 2種高可用方式， Spring-Cloud-Config-Client配置存在兩種策略

  1. 通過ConfigServer獲取注冊中心地址和其他配置
  2. 通過注冊中心獲取ConfigServer地址，然后獲得其他配置

• 參考國內(nèi)比較成熟的分布式集中配置，比如百度Disconf，攜程Apollo等基本都是第1種策略，好處是唯一需要本地寫死的是配置中心的參數(shù).

• 但是Spring Cloud 1.X 并不支持ConfigServer集群的高可用配置。需要單獨(dú)將spring-cloud-starter-config升級到2.x（可以和其他1.x組件混用）

• 升級后就可以配多個(gè)地址了，如下：

spring:
  application:
    name: user
  cloud:
    config:
      fail-fast: true
      profile: dev
      label: master
      uri: http://localhost:8761/config, http://localhost:8762/config, http://localhost:8763/config

• 但是網(wǎng)上更多介紹的是第二種方案，這里也貼出來。配置項(xiàng)更多了，需要同時(shí)指定configserver和eureka

spring:
  application:
    name: user
  cloud:
    config:
      fail-fast: true
      profile: dev
      label: master
      discovery:
        enabled: true
        serviceId: dashboard
      
eureka:
  client:
    register-with-eureka: true
    fetch-registry: true
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/,http://localhost2:8762/eureka,http://localhost3:8763/eureka

• 啟動(dòng)過程和ConfigServer注入過程類似
• ConfigServiceBootstrapConfiguration -> ConfigServicePropertySourceLocator -> locate

public PropertySource<?> locate(Environment environment) {
    CompositePropertySource composite = new CompositePropertySource("configService");
    ...
    RestTemplate restTemplate = getSecureRestTemplate(properties);
    ...
    Environment result = getRemoteEnvironment(restTemplate...);
    ...
    for (PropertySource source : result.getPropertySources()) {
        ...
        composite.addPropertySource(source);
    }
    ...
}

• 該服務(wù)實(shí)現(xiàn)了PropertySourceLocator接口，在PropertySourceBootstrapConfiguration#init中會(huì)被注入到bootStrap的context中

• 方案2比方案1多一個(gè)環(huán)節(jié)，configServer 的 uri 是由注冊中心獲取的

• DiscoveryClientConfigServiceBootstrapConfiguration#refresh

@ConditionalOnProperty(value = "spring.cloud.config.discovery.enabled", matchIfMissing = false)
@Configuration
@EnableDiscoveryClient
public class DiscoveryClientConfigServiceBootstrapConfiguration {
    void refresh() {
        String serviceId = this.config.getDiscovery().getServiceId();
        List<ServiceInstance> serviceInstances = this.instanceProvider
                    .getConfigServerInstances(serviceId);
        for (int i = 0; i < serviceInstances.size(); i++) {
                ServiceInstance server = serviceInstances.get(i);
                String url = getHomePage(server);
                listOfUrls.add(url);
        }
        ...
        configClientProperties.setUri(listOfUrls);
    }
}