关于springcloud:聊聊springcloud项目同时存在多个注册中心客户端采坑记

前言

前段时间业务部门有这么一个业务场景，他们本人微服务注册核心是用 eureka，他们有一些服务接口要调用兄弟部门的接口，他们定了一个服务调用计划，业务部门间接把他们服务注册到兄弟部门的注册核心，而后走 rpc 调用，兄弟部门注册核心是用 nacos。

一开始业务部门研发间接在在 pom.xml 这么引入

    <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>

        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>

而后我的项目启动报了如下错

Field registration in org.springframework.cloud.client.serviceregistry.ServiceRegistryAutoConfiguration$ServiceRegistryEndpointConfiguration required a single bean, but 2 were found:
    - nacosRegistration: defined by method 'nacosRegistration' in class path resource [com/alibaba/cloud/nacos/NacosDiscoveryAutoConfiguration.class]
    - eurekaRegistration: defined in BeanDefinition defined in class path resource [org/springframework/cloud/netflix/eureka/EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration.class]

业务部门是这么解决的，每次发版时，如果是要纳入兄弟部门的微服务，他们就先手动正文掉 eureka 的客户端依赖。

起初业务部门就向咱们部门提了一个需要，pom 引入多个注册核心客户端，我的项目也要能失常启动

需要剖析

从我的项目异样剖析

Field registration in org.springframework.cloud.client.serviceregistry.ServiceRegistryAutoConfiguration$ServiceRegistryEndpointConfiguration required a single bean, but 2 were found:
    - nacosRegistration: defined by method 'nacosRegistration' in class path resource [com/alibaba/cloud/nacos/NacosDiscoveryAutoConfiguration.class]
    - eurekaRegistration: defined in BeanDefinition defined in class path resource [org/springframework/cloud/netflix/eureka/EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration.class]

能够看出 springcloud 默认的服务注册是只反对单服务注册核心。因而咱们解决的计划要么扩大 springcloud 源码，让它反对多注册核心，要么就是通知 springcloud 当存在多种注册核心客户端时，抉择一种咱们想要的注册核心客户端

本文就选实现绝对容易的计划，当存在多种注册核心客户端时，咱们通知 springcloud，咱们想选的注册核心

实现计划

目前根本只有和 springboot 集成的开源我的项目，能够说大部分应用了主动拆卸，因而咱们的解决思路也是从主动拆卸搞起

前置常识

protected AutoConfigurationEntry getAutoConfigurationEntry(AutoConfigurationMetadata autoConfigurationMetadata,
            AnnotationMetadata annotationMetadata) {if (!isEnabled(annotationMetadata)) {return EMPTY_ENTRY;}
        AnnotationAttributes attributes = getAttributes(annotationMetadata);
        List<String> configurations = getCandidateConfigurations(annotationMetadata, attributes);
        configurations = removeDuplicates(configurations);
        Set<String> exclusions = getExclusions(annotationMetadata, attributes);
        checkExcludedClasses(configurations, exclusions);
        configurations.removeAll(exclusions);
        configurations = filter(configurations, autoConfigurationMetadata);
        fireAutoConfigurationImportEvents(configurations, exclusions);
        return new AutoConfigurationEntry(configurations, exclusions);
    }

    private List<String> filter(List<String> configurations, AutoConfigurationMetadata autoConfigurationMetadata) {long startTime = System.nanoTime();
        String[] candidates = StringUtils.toStringArray(configurations);
        boolean[] skip = new boolean[candidates.length];
        boolean skipped = false;
        for (AutoConfigurationImportFilter filter : getAutoConfigurationImportFilters()) {invokeAwareMethods(filter);
            boolean[] match = filter.match(candidates, autoConfigurationMetadata);
            for (int i = 0; i < match.length; i++) {if (!match[i]) {skip[i] = true;
                    candidates[i] = null;
                    skipped = true;
                }
            }
        }
        if (!skipped) {return configurations;}
        List<String> result = new ArrayList<>(candidates.length);
        for (int i = 0; i < candidates.length; i++) {if (!skip[i]) {result.add(candidates[i]);
            }
        }
        if (logger.isTraceEnabled()) {int numberFiltered = configurations.size() - result.size();
            logger.trace("Filtered" + numberFiltered + "auto configuration class in"
                    + TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startTime) + "ms");
        }
        return new ArrayList<>(result);
    }

这两个代码片段，一个是主动拆卸的代码片段，一个是过滤候选哪些不须要进行主动拆卸

计划一：利用 AutoConfigurationImportFilter + 自定义标识

实现的原理： 当自定的标识为 nacos，通过 AutoConfigurationImportFilter 排除 eureka 的主动拆卸；反之排除 nacos 的主动拆卸

1、外围实现

public class RegistrationCenterAutoConfigurationImportFilter implements AutoConfigurationImportFilter, EnvironmentAware {

    private Environment environment;

    /**
     * 因为 springboot 主动拆卸，默认会把 spring.factories 的配置的类先全副加载到候选汇合中，* 因而当咱们代码配置启用 nacos，则需把其余注册核心，比方 eureka 先从候选汇合排除
     * @param autoConfigurationClasses
     * @param autoConfigurationMetadata
     * @return
     */
    @Override
    public boolean[] match(String[] autoConfigurationClasses, AutoConfigurationMetadata autoConfigurationMetadata) {Set<String> activeProfiles = Arrays.stream(environment.getActiveProfiles()).collect(Collectors.toSet());

        if(activeProfiles.contains(RegistrationCenterConstants.ACTIVE_PROFILE_NACOS)){return excludeMissMatchRegistrationAutoConfiguration(autoConfigurationClasses, new String[]{RegistrationCenterConstants.EUREKA_AUTO_CONFIGURATION_CLASSES});

        }else if (activeProfiles.contains(RegistrationCenterConstants.ACTIVE_PROFILE_EUREKA)){return excludeMissMatchRegistrationAutoConfiguration(autoConfigurationClasses, new String[]{RegistrationCenterConstants.NACOS_DISCOVERY_AUTO_CONFIGURATION_CLASSES,RegistrationCenterConstants.NACOS_DISCOVERY_CLIENT_AUTO_CONFIGURATION_CLASSES,RegistrationCenterConstants.NACOS_DISCOVERY_ENDPOINT_AUTO_CONFIGURATION_CLASSES});
        }


        return new boolean[0];
    }

    private boolean[] excludeMissMatchRegistrationAutoConfiguration(String[] autoConfigurationClasses,String[] needExcludeRegistrationAutoConfigurationClasse) {Map<String,Boolean> needExcludeRegistrationAutoConfigurationClzMap = initNeedExcludeRegistrationAutoConfigurationClzMap(needExcludeRegistrationAutoConfigurationClasse);
        boolean[] match = new boolean[autoConfigurationClasses.length];
        for (int i = 0; i < autoConfigurationClasses.length; i++) {String autoConfigurationClz = autoConfigurationClasses[i];
            match[i] = !needExcludeRegistrationAutoConfigurationClzMap.containsKey(autoConfigurationClz);

        }

        return match;
    }

    private Map<String,Boolean> initNeedExcludeRegistrationAutoConfigurationClzMap(String[] needExcludeRegistrationAutoConfigurationClasse){Map<String,Boolean> needExcludeRegistrationAutoConfigurationClzMap = new HashMap<>();
        for (String needExcludeRegistrationAutoConfigurationClz : needExcludeRegistrationAutoConfigurationClasse) {needExcludeRegistrationAutoConfigurationClzMap.put(needExcludeRegistrationAutoConfigurationClz,false);
        }

        return needExcludeRegistrationAutoConfigurationClzMap;

    }

    @Override
    public void setEnvironment(Environment environment) {this.environment = environment;}


}

2、配置 spring.factories

org.springframework.boot.autoconfigure.AutoConfigurationImportFilter=\
com.github.lybgeek.registration.autoconfigure.filter.RegistrationCenterAutoConfigurationImportFilter

计划二：利用 application-${指定注册核心标识} + spring.profiles.active

1、在要激活的注册核心的文件禁用其余注册核心客户端

比方 appliication-nacos.yml 禁用 eureka

spring:
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848

# 禁用 eureka 客户端主动注册
eureka:
  client:
    enabled: false

2、激活想要注册的注册核心

spring:
  application:
    name: springboot-registration-client
  profiles:
    active: nacos

总结

这两种计划集体是比拟举荐计划二，因为改变最小。计划一比拟实用于没有提供是否须要激活注册核心开关的注册核心。其次如果咱们要排除某些开源主动拆卸的组件，也能够思考用计划一

demo 链接

https://github.com/lyb-geek/springboot-learning/tree/master/springboot-registrationcenter-switch