聊聊spring-cloud的ConsulServer

序

本文主要研究一下 spring cloud 的 ConsulServer

ConsulServer

spring-cloud-consul-discovery-2.1.2.RELEASE-sources.jar!/org/springframework/cloud/consul/discovery/ConsulServer.java

public class ConsulServer extends Server {

    private final MetaInfo metaInfo;

    private final HealthService service;

    private final Map<String, String> metadata;

    public ConsulServer(final HealthService healthService) {super(findHost(healthService), healthService.getService().getPort());
        this.service = healthService;
        this.metadata = ConsulServerUtils.getMetadata(this.service);
        this.metaInfo = new MetaInfo() {
            @Override
            public String getAppName() {return ConsulServer.this.service.getService().getService();}

            @Override
            public String getServerGroup() {return getMetadata().get("group");
            }

            @Override
            public String getServiceIdForDiscovery() {return null;}

            @Override
            public String getInstanceId() {return ConsulServer.this.service.getService().getId();}
        };

        setAlive(isPassingChecks());
    }

    @Override
    public MetaInfo getMetaInfo() {return this.metaInfo;}

    public HealthService getHealthService() {return this.service;}

    public Map<String, String> getMetadata() {return this.metadata;}

    public boolean isPassingChecks() {for (Check check : this.service.getChecks()) {if (check.getStatus() != Check.CheckStatus.PASSING) {return false;}
        }
        return true;
    }

}

• ConsulServer 继承了 com.netflix.loadbalancer.Server；其构造器会调用 isPassingChecks 方法来 setAlive，它通过 HealthService 来获取 checks 的状态

ConsulServerList

spring-cloud-consul-discovery-2.1.2.RELEASE-sources.jar!/org/springframework/cloud/consul/discovery/ConsulServerList.java

public class ConsulServerList extends AbstractServerList<ConsulServer> {

    private final ConsulClient client;

    private final ConsulDiscoveryProperties properties;

    private String serviceId;

    public ConsulServerList(ConsulClient client, ConsulDiscoveryProperties properties) {
        this.client = client;
        this.properties = properties;
    }

    protected ConsulClient getClient() {return this.client;}

    protected ConsulDiscoveryProperties getProperties() {return this.properties;}

    protected String getServiceId() {return this.serviceId;}

    @Override
    public void initWithNiwsConfig(IClientConfig clientConfig) {this.serviceId = clientConfig.getClientName();
    }

    @Override
    public List<ConsulServer> getInitialListOfServers() {return getServers();
    }

    @Override
    public List<ConsulServer> getUpdatedListOfServers() {return getServers();
    }

    private List<ConsulServer> getServers() {if (this.client == null) {return Collections.emptyList();
        }
        String tag = getTag(); // null is ok
        Response<List<HealthService>> response = this.client.getHealthServices(this.serviceId, tag, this.properties.isQueryPassing(),
                createQueryParamsForClientRequest(), this.properties.getAclToken());
        if (response.getValue() == null || response.getValue().isEmpty()) {return Collections.emptyList();
        }
        return transformResponse(response.getValue());
    }

    /**
     * Transforms the response from Consul in to a list of usable {@link ConsulServer}s.
     * @param healthServices the initial list of servers from Consul. Guaranteed to be
     * non-empty list
     * @return ConsulServer instances
     * @see ConsulServer#ConsulServer(HealthService)
     */
    protected List<ConsulServer> transformResponse(List<HealthService> healthServices) {List<ConsulServer> servers = new ArrayList<>();
        for (HealthService service : healthServices) {ConsulServer server = new ConsulServer(service);
            if (server.getMetadata()
                    .containsKey(this.properties.getDefaultZoneMetadataName())) {server.setZone(server.getMetadata()
                        .get(this.properties.getDefaultZoneMetadataName()));
            }
            servers.add(server);
        }
        return servers;
    }

    /**
     * This method will create the {@link QueryParams} to use when retrieving the services
     * from Consul. By default {@link QueryParams#DEFAULT} is used. In case a datacenter
     * is specified for the current serviceId {@link QueryParams#datacenter} is set.
     * @return an instance of {@link QueryParams}
     */
    protected QueryParams createQueryParamsForClientRequest() {String datacenter = getDatacenter();
        if (datacenter != null) {return new QueryParams(datacenter);
        }
        return QueryParams.DEFAULT;
    }

    protected String getTag() {return this.properties.getQueryTagForService(this.serviceId);
    }

    protected String getDatacenter() {return this.properties.getDatacenters().get(this.serviceId);
    }

    @Override
    public String toString() {final StringBuilder sb = new StringBuilder("ConsulServerList{");
        sb.append("serviceId='").append(this.serviceId).append('\'');
        sb.append(", tag=").append(getTag());
        sb.append('}');
        return sb.toString();}

}

• ConsulServerList 继承了 com.netflix.loadbalancer.AbstractServerList；其 getInitialListOfServers 及 getUpdatedListOfServers 方法都会调用 getServers 方法；它通过 ConsulClient.getHealthServices 来获取指定 serviceId 的 HealthService 列表，然后通过 transformResponse 方法包装为 ConsulServer 列表

ConsulRibbonClientConfiguration

spring-cloud-consul-discovery-2.1.2.RELEASE-sources.jar!/org/springframework/cloud/consul/discovery/ConsulRibbonClientConfiguration.java

@Configuration
public class ConsulRibbonClientConfiguration {

    protected static final String VALUE_NOT_SET = "__not__set__";

    protected static final String DEFAULT_NAMESPACE = "ribbon";

    @Autowired
    private ConsulClient client;

    @Value("${ribbon.client.name}")
    private String serviceId = "client";

    public ConsulRibbonClientConfiguration() {}

    public ConsulRibbonClientConfiguration(String serviceId) {this.serviceId = serviceId;}

    @Bean
    @ConditionalOnMissingBean
    public ServerList<?> ribbonServerList(IClientConfig config,
            ConsulDiscoveryProperties properties) {ConsulServerList serverList = new ConsulServerList(this.client, properties);
        serverList.initWithNiwsConfig(config);
        return serverList;
    }

    @Bean
    @ConditionalOnMissingBean
    public ServerListFilter<Server> ribbonServerListFilter() {return new HealthServiceServerListFilter();
    }

    @Bean
    @ConditionalOnMissingBean
    public IPing ribbonPing() {return new ConsulPing();
    }

    @Bean
    @ConditionalOnMissingBean
    public ConsulServerIntrospector serverIntrospector() {return new ConsulServerIntrospector();
    }

    @PostConstruct
    public void preprocess() {setProp(this.serviceId, DeploymentContextBasedVipAddresses.key(), this.serviceId);
        setProp(this.serviceId, EnableZoneAffinity.key(), "true");
    }

    protected void setProp(String serviceId, String suffix, String value) {
        // how to set the namespace properly?
        String key = getKey(serviceId, suffix);
        DynamicStringProperty property = getProperty(key);
        if (property.get().equals(VALUE_NOT_SET)) {ConfigurationManager.getConfigInstance().setProperty(key, value);
        }
    }

    protected DynamicStringProperty getProperty(String key) {return DynamicPropertyFactory.getInstance().getStringProperty(key, VALUE_NOT_SET);
    }

    protected String getKey(String serviceId, String suffix) {return serviceId + "." + DEFAULT_NAMESPACE + "." + suffix;}

}

• ConsulRibbonClientConfiguration 注入了 ribbonServerList，其创建的是 ConsulServerList

小结

• ConsulServer 继承了 com.netflix.loadbalancer.Server；其构造器会调用 isPassingChecks 方法来 setAlive，它通过 HealthService 来获取 checks 的状态
• ConsulServerList 继承了 com.netflix.loadbalancer.AbstractServerList；其 getInitialListOfServers 及 getUpdatedListOfServers 方法都会调用 getServers 方法；它通过 ConsulClient.getHealthServices 来获取指定 serviceId 的 HealthService 列表，然后通过 transformResponse 方法包装为 ConsulServer 列表
• ConsulRibbonClientConfiguration 注入了 ribbonServerList，其创建的是 ConsulServerList

doc

• ConsulServer