一、问题背景
在开发某个公共应用时，笔者发现该公共应用的数据是所有测试环境（假设存在 dev/dev2/dev3）通用的。
这就意味着只需部署一个应用，就能满足所有测试环境的需求；也意味着所有测试环境都需要调用该公共应用，而不同测试环境的应用注册在不同的 Nacos 命名空间。
二、两种解决方案
如果所有测试环境都需要调用该公共应用，有两种可行的方案。第一种，将该公共服务同时注册到不同的测试环境所对应的命名空间中。
第二种，将公共应用注册到单独的命名空间，不同的测试环境能够跨命名空间访问该应用。
三、详细的问题解决过程
先行交代笔者的版本号配置。Nacos 客户端版本号为 NACOS 1.4.1；Java 项目的 Nacos 版本号如下。
最初想法是将该公共应用同时注册到多个命名空间下。在查找资料的过程中，团队成员在 GitHub 上发现了一篇类似问题的博客分享：Registration Center: Can services in different namespaces be called from each other? #1176。
01 注册多个命名空间
从该博客中，我们看到其他程序员朋友也遇到了类似的公共服务的需求。在本篇文章中，笔者将进一步分享实现思路以及示例代码。
说明：以下代码内容来自用户 chuntaojun 的分享。
shareNamespace={namespaceId[:group]},{namespaceId[:group]} @RunWith(SpringRunner.class)
@SpringBootTest(classes = NamingApp.class, properties = {"server.servlet.context-path=/nacos"},
webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
public class SelectServiceInShareNamespace_ITCase {
private NamingService naming1;
private NamingService naming2;
@LocalServerPort
private int port;
@Before
public void init() throws Exception{
NamingBase.prepareServer(port);
if (naming1 == null) {
Properties properties = new Properties();
properties.setProperty(PropertyKeyConst.SERVER_ADDR, "127.0.0.1"+":"+port);
properties.setProperty(PropertyKeyConst.SHARE_NAMESPACE, "57425802-3058-4507-9a73-3229b9f00a36");
naming1 = NamingFactory.createNamingService(properties);
Properties properties2 = new Properties();
properties2.setProperty(PropertyKeyConst.SERVER_ADDR, "127.0.0.1"+":"+port);
properties2.setProperty(PropertyKeyConst.NAMESPACE, "57425802-3058-4507-9a73-3229b9f00a36");
naming2 = NamingFactory.createNamingService(properties2);
}
while (true) {
if (!"UP".equals(naming1.getServerStatus())) {
Thread.sleep(1000L);
continue;
}
break;
}
}
@Test
public void testSelectInstanceInShareNamespaceNoGroup() throws NacosException, InterruptedException {
String service1 = randomDomainName();
String service2 = randomDomainName();
naming1.registerInstance(service1, "127.0.0.1", 90);
naming2.registerInstance(service2, "127.0.0.2", 90);
Thread.sleep(1000);
List instances = naming1.getAllInstances(service2);
Assert.assertEquals(1, instances.size());
Assert.assertEquals(service2, NamingUtils.getServiceName(instances.get(0).getServiceName()));
}
@Test
public void testSelectInstanceInShareNamespaceWithGroup() throws NacosException, InterruptedException {
String service1 = randomDomainName();
String service2 = randomDomainName();
naming2.registerInstance(service1, groupName, "127.0.0.1", 90);
naming3.registerInstance(service2, "127.0.0.2", 90);
Thread.sleep(1000);
List instances = naming3.getAllInstances(service1);
Assert.assertEquals(1, instances.size());
Assert.assertEquals(service1, NamingUtils.getServiceName(instances.get(0).getServiceName()));
Assert.assertEquals(groupName, NamingUtils.getServiceName(NamingUtils.getGroupName(instances.get(0).getServiceName())));
}
} 进一步考虑后发现该解决方案可能不太契合当前遇到的问题。公司目前的开发测试环境有很多个，并且不确定以后会不会继续增加。
如果每增加一个环境，都需要修改一次公共服务的配置，并且重启一次公共服务，着实太麻烦了。倒不如反其道而行，让其他的服务器实现跨命名空间访问公共服务。
02 跨命名空间访问
针对实际问题查找资料时，我们找到了类似的参考分享《重写 Nacos 服务发现逻辑动态修改远程服务IP地址》。
跟着博客思路看代码，笔者了解到服务发现的主要相关类是 NacosNamingService, NacosDiscoveryProperties, NacosDiscoveryAutoConfiguration。
然后，笔者将博客的示例代码复制过来，试着进行如下调试：
@Slf4j
@Configuration
@ConditionalOnNacosDiscoveryEnabled
@ConditionalOnProperty(
name = {"spring.profiles.active"},
havingValue = "dev"
)
@AutoConfigureBefore({NacosDiscoveryClientAutoConfiguration.class})
public class DevEnvironmentNacosDiscoveryClient {
@Bean
@ConditionalOnMissingBean
public NacosDiscoveryProperties nacosProperties() {
return new DevEnvironmentNacosDiscoveryProperties();
}
static class DevEnvironmentNacosDiscoveryProperties extends NacosDiscoveryProperties {
private NamingService namingService;
@Override
public NamingService namingServiceInstance() {
if (null != this.namingService) {
return this.namingService;
} else {
Properties properties = new Properties();
properties.put("serverAddr", super.getServerAddr());
properties.put("namespace", super.getNamespace());
properties.put("com.alibaba.nacos.naming.log.filename", super.getLogName());
if (super.getEndpoint().contains(":")) {
int index = super.getEndpoint().indexOf(":");
properties.put("endpoint", super.getEndpoint().substring(0, index));
properties.put("endpointPort", super.getEndpoint().substring(index + 1));
} else {
properties.put("endpoint", super.getEndpoint());
}
properties.put("accessKey", super.getAccessKey());
properties.put("secretKey", super.getSecretKey());
properties.put("clusterName", super.getClusterName());
properties.put("namingLoadCacheAtStart", super.getNamingLoadCacheAtStart());
try {
this.namingService = new DevEnvironmentNacosNamingService(properties);
} catch (Exception var3) {
log.error("create naming service error!properties={},e=,", this, var3);
return null;
}
return this.namingService;
}
}
}
static class DevEnvironmentNacosNamingService extends NacosNamingService {
public DevEnvironmentNacosNamingService(Properties properties) {
super(properties);
}
@Override
public List selectInstances(String serviceName, List clusters, boolean healthy) throws NacosException {
List instances = super.selectInstances(serviceName, clusters, healthy);
instances.stream().forEach(instance -> instance.setIp("10.101.232.24"));
return instances;
}
}
} 调试后发现博客提供的代码并不能满足笔者的需求，还得进一步深入探索。
但幸运的是，调试过程发现 Nacos 服务发现的关键类是 com.alibaba.cloud.nacos.discovery.NacosServiceDiscovery，其中的关键方法是 getInstances() 和 getServices()，即「返回指定服务 ID 的所有服务实例」和「获取所有服务的名称」。
也就是说，对 getInstances() 方法进行重写肯定能实现本次目标——跨命名空间访问公共服务。
/**
* Return all instances for the given service.
* @param serviceId id of service
* @return list of instances
* @throws NacosException nacosException
*/
public List getInstances(String serviceId) throws NacosException {
String group = discoveryProperties.getGroup();
List instances = discoveryProperties.namingServiceInstance()
.selectInstances(serviceId, group, true);
return hostToServiceInstanceList(instances, serviceId);
}
/**
* Return the names of all services.
* @return list of service names
* @throws NacosException nacosException
*/
public List getServices() throws NacosException {
String group = discoveryProperties.getGroup();
ListView services = discoveryProperties.namingServiceInstance()
.getServicesOfServer(1, Integer.MAX_VALUE, group);
return services.getData();
} 03 最终解决思路及代码示例
具体的解决方案思路大致如下：
- 生成一个共享配置类
NacosShareProperties，用来配置共享公共服务的namespace和group； - 重写配置类
NacosDiscoveryProperties（新：NacosDiscoveryPropertiesV2），将新增的共享配置类作为属性放进该配置类，后续会用到； - 重写服务发现类
NacosServiceDiscovery（新：NacosServiceDiscoveryV2），这是最关键的逻辑； - 重写自动配置类
NacosDiscoveryAutoConfiguration，将自定义相关类比 Nacos 原生类更早的注入容器。
最终代码中用到了一些工具类，可以自行补充完整。
/**
*
* @description: 共享nacos属性
* @author: rookie0peng
* @date: 2022/8/29 15:22
*
*/
@Configuration
@ConfigurationProperties(prefix = "nacos.share")
public class NacosShareProperties {
private final Map> NAMESPACE_TO_GROUP_NAME_MAP = new ConcurrentHashMap<>();
/**
* 共享nacos实体列表
*/
private List entities;
public List getEntities() {
return entities;
}
public void setEntities(List entities) {
this.entities = entities;
}
public Map> getNamespaceGroupMap() {
safeStream(entities).filter(entity -> nonNull(entity) && nonNull(entity.getNamespace()))
.forEach(entity -> {
Set groupNames = NAMESPACE_TO_GROUP_NAME_MAP.computeIfAbsent(entity.getNamespace(), k -> new HashSet<>());
if (nonNull(entity.getGroupNames()))
groupNames.addAll(entity.getGroupNames());
});
return new HashMap<>(NAMESPACE_TO_GROUP_NAME_MAP);
}
@Override
public String toString() {
return "NacosShareProperties{" +
"entities=" + entities +
'}';
}
/**
* 共享nacos实体
*/
public static final class NacosShareEntity {
/**
* 命名空间
*/
private String namespace;
/**
* 分组
*/
private List groupNames;
public String getNamespace() {
return namespace;
}
public void setNamespace(String namespace) {
this.namespace = namespace;
}
public List getGroupNames() {
return groupNames;
}
public void setGroupNames(List groupNames) {
this.groupNames = groupNames;
}
@Override
public String toString() {
return "NacosShareEntity{" +
"namespace='" + namespace + '\'' +
", groupNames=" + groupNames +
'}';
}
}
} /**
* @description: naocs服务发现属性重写
* @author: rookie0peng
* @date: 2022/8/30 1:19
*/
public class NacosDiscoveryPropertiesV2 extends NacosDiscoveryProperties {
private static final Logger log = LoggerFactory.getLogger(NacosDiscoveryPropertiesV2.class);
private final NacosShareProperties nacosShareProperties;
private static final Map NAMESPACE_TO_NAMING_SERVICE_MAP = new ConcurrentHashMap<>();
public NacosDiscoveryPropertiesV2(NacosShareProperties nacosShareProperties) {
super();
this.nacosShareProperties = nacosShareProperties;
}
public Map shareNamingServiceInstances() {
if (!NAMESPACE_TO_NAMING_SERVICE_MAP.isEmpty()) {
return new HashMap<>(NAMESPACE_TO_NAMING_SERVICE_MAP);
}
List entities = Optional.ofNullable(nacosShareProperties)
.map(NacosShareProperties::getEntities).orElse(Collections.emptyList());
entities.stream().filter(entity -> nonNull(entity) && nonNull(entity.getNamespace()))
.filter(PredicateUtil.distinctByKey(NacosShareProperties.NacosShareEntity::getNamespace))
.forEach(entity -> {
try {
NamingService namingService = NacosFactory.createNamingService(getNacosProperties(entity.getNamespace()));
if (namingService != null) {
NAMESPACE_TO_NAMING_SERVICE_MAP.put(entity.getNamespace(), namingService);
}
} catch (Exception e) {
log.error("create naming service error! properties={}, e=", this, e);
}
});
return new HashMap<>(NAMESPACE_TO_NAMING_SERVICE_MAP);
}
private Properties getNacosProperties(String namespace) {
Properties properties = new Properties();
properties.put(SERVER_ADDR, getServerAddr());
properties.put(USERNAME, Objects.toString(getUsername(), ""));
properties.put(PASSWORD, Objects.toString(getPassword(), ""));
properties.put(NAMESPACE, namespace);
properties.put(UtilAndComs.NACOS_NAMING_LOG_NAME, getLogName());
String endpoint = getEndpoint();
if (endpoint.contains(":")) {
int index = endpoint.indexOf(":");
properties.put(ENDPOINT, endpoint.substring(0, index));
properties.put(ENDPOINT_PORT, endpoint.substring(index + 1));
}
else {
properties.put(ENDPOINT, endpoint);
}
properties.put(ACCESS_KEY, getAccessKey());
properties.put(SECRET_KEY, getSecretKey());
properties.put(CLUSTER_NAME, getClusterName());
properties.put(NAMING_LOAD_CACHE_AT_START, getNamingLoadCacheAtStart());
// enrichNacosDiscoveryProperties(properties);
return properties;
}
} /**
* @description: naocs服务发现重写
* @author: rookie0peng
* @date: 2022/8/30 1:10
*/
public class NacosServiceDiscoveryV2 extends NacosServiceDiscovery {
private final NacosDiscoveryPropertiesV2 discoveryProperties;
private final NacosShareProperties nacosShareProperties;
private final NacosServiceManager nacosServiceManager;
public NacosServiceDiscoveryV2(NacosDiscoveryPropertiesV2 discoveryProperties, NacosShareProperties nacosShareProperties, NacosServiceManager nacosServiceManager) {
super(discoveryProperties, nacosServiceManager);
this.discoveryProperties = discoveryProperties;
this.nacosShareProperties = nacosShareProperties;
this.nacosServiceManager = nacosServiceManager;
}
/**
* Return all instances for the given service.
* @param serviceId id of service
* @return list of instances
* @throws NacosException nacosException
*/
public List getInstances(String serviceId) throws NacosException {
String group = discoveryProperties.getGroup();
List instances = discoveryProperties.namingServiceInstance()
.selectInstances(serviceId, group, true);
if (isEmpty(instances)) {
Map> namespaceGroupMap = nacosShareProperties.getNamespaceGroupMap();
Map namespace2NamingServiceMap = discoveryProperties.shareNamingServiceInstances();
for (Map.Entry entry : namespace2NamingServiceMap.entrySet()) {
String namespace;
NamingService namingService;
if (isNull(namespace = entry.getKey()) || isNull(namingService = entry.getValue()))
continue;
Set groupNames = namespaceGroupMap.get(namespace);
List shareInstances;
if (isEmpty(groupNames)) {
shareInstances = namingService.selectInstances(serviceId, group, true);
if (nonEmpty(shareInstances))
break;
} else {
shareInstances = new ArrayList<>();
for (String groupName : groupNames) {
List subShareInstances = namingService.selectInstances(serviceId, groupName, true);
if (nonEmpty(subShareInstances)) {
shareInstances.addAll(subShareInstances);
}
}
}
if (nonEmpty(shareInstances)) {
instances = shareInstances;
break;
}
}
}
return hostToServiceInstanceList(instances, serviceId);
}
/**
* Return the names of all services.
* @return list of service names
* @throws NacosException nacosException
*/
public List getServices() throws NacosException {
String group = discoveryProperties.getGroup();
ListView services = discoveryProperties.namingServiceInstance()
.getServicesOfServer(1, Integer.MAX_VALUE, group);
return services.getData();
}
public static List hostToServiceInstanceList(
List instances, String serviceId) {
List result = new ArrayList<>(instances.size());
for (Instance instance : instances) {
ServiceInstance serviceInstance = hostToServiceInstance(instance, serviceId);
if (serviceInstance != null) {
result.add(serviceInstance);
}
}
return result;
}
public static ServiceInstance hostToServiceInstance(Instance instance,
String serviceId) {
if (instance == null || !instance.isEnabled() || !instance.isHealthy()) {
return null;
}
NacosServiceInstance nacosServiceInstance = new NacosServiceInstance();
nacosServiceInstance.setHost(instance.getIp());
nacosServiceInstance.setPort(instance.getPort());
nacosServiceInstance.setServiceId(serviceId);
Map metadata = new HashMap<>();
metadata.put("nacos.instanceId", instance.getInstanceId());
metadata.put("nacos.weight", instance.getWeight() + "");
metadata.put("nacos.healthy", instance.isHealthy() + "");
metadata.put("nacos.cluster", instance.getClusterName() + "");
metadata.putAll(instance.getMetadata());
nacosServiceInstance.setMetadata(metadata);
if (metadata.containsKey("secure")) {
boolean secure = Boolean.parseBoolean(metadata.get("secure"));
nacosServiceInstance.setSecure(secure);
}
return nacosServiceInstance;
}
private NamingService namingService() {
return nacosServiceManager
.getNamingService(discoveryProperties.getNacosProperties());
}
} /**
* @description: 重写nacos服务发现的自动配置
* @author: rookie0peng
* @date: 2022/8/30 1:08
*/
@Configuration(proxyBeanMethods = false)
@ConditionalOnDiscoveryEnabled
@ConditionalOnNacosDiscoveryEnabled
@AutoConfigureBefore({NacosDiscoveryAutoConfiguration.class})
public class NacosDiscoveryAutoConfigurationV2 {
@Bean
@ConditionalOnMissingBean
public NacosDiscoveryPropertiesV2 nacosProperties(NacosShareProperties nacosShareProperties) {
return new NacosDiscoveryPropertiesV2(nacosShareProperties);
}
@Bean
@ConditionalOnMissingBean
public NacosServiceDiscovery nacosServiceDiscovery(
NacosDiscoveryPropertiesV2 discoveryPropertiesV2, NacosShareProperties nacosShareProperties, NacosServiceManager nacosServiceManager
) {
return new NacosServiceDiscoveryV2(discoveryPropertiesV2, nacosShareProperties, nacosServiceManager);
}
}
本以为问题到这就结束了，但最后自测时发现程序根本不走 Nacos 的服务发现逻辑，而是执行 Ribbon 的负载均衡逻辑com.netflix.loadbalancer.AbstractLoadBalancerRule。
不过实现类是 com.alibaba.cloud.nacos.ribbon.NacosRule，继续基于 NacosRule 重写负载均衡。
/**
* @description: 共享nacos命名空间规则
* @author: rookie0peng
* @date: 2022/8/31 2:04
*/
public class ShareNacosNamespaceRule extends AbstractLoadBalancerRule {
private static final Logger LOGGER = LoggerFactory.getLogger(ShareNacosNamespaceRule.class);
@Autowired
private NacosDiscoveryPropertiesV2 nacosDiscoveryPropertiesV2;
@Autowired
private NacosShareProperties nacosShareProperties;
/**
* 重写choose方法
*
* @param key
* @return
*/
@SneakyThrows
@Override
public Server choose(Object key) {
try {
String clusterName = this.nacosDiscoveryPropertiesV2.getClusterName();
DynamicServerListLoadBalancer loadBalancer = (DynamicServerListLoadBalancer) getLoadBalancer();
String name = loadBalancer.getName();
NamingService namingService = nacosDiscoveryPropertiesV2
.namingServiceInstance();
List instances = namingService.selectInstances(name, true);
if (CollectionUtils.isEmpty(instances)) {
LOGGER.warn("no instance in service {}, then to get share service's instance", name);
List shareNamingService = this.getShareNamingService(name);
if (nonEmpty(shareNamingService))
instances = shareNamingService;
else
return null;
}
List instancesToChoose = instances;
if (org.apache.commons.lang3.StringUtils.isNotBlank(clusterName)) {
List sameClusterInstances = instances.stream()
.filter(instance -> Objects.equals(clusterName,
instance.getClusterName()))
.collect(Collectors.toList());
if (!CollectionUtils.isEmpty(sameClusterInstances)) {
instancesToChoose = sameClusterInstances;
}
else {
LOGGER.warn(
"A cross-cluster call occurs，name = {}, clusterName = {}, instance = {}",
name, clusterName, instances);
}
}
Instance instance = ExtendBalancer.getHostByRandomWeight2(instancesToChoose);
return new NacosServer(instance);
}
catch (Exception e) {
LOGGER.warn("NacosRule error", e);
return null;
}
}
@Override
public void initWithNiwsConfig(IClientConfig iClientConfig) {
}
private List getShareNamingService(String serviceId) throws NacosException {
List instances = Collections.emptyList();
Map> namespaceGroupMap = nacosShareProperties.getNamespaceGroupMap();
Map namespace2NamingServiceMap = nacosDiscoveryPropertiesV2.shareNamingServiceInstances();
for (Map.Entry entry : namespace2NamingServiceMap.entrySet()) {
String namespace;
NamingService namingService;
if (isNull(namespace = entry.getKey()) || isNull(namingService = entry.getValue()))
continue;
Set groupNames = namespaceGroupMap.get(namespace);
List shareInstances;
if (isEmpty(groupNames)) {
shareInstances = namingService.selectInstances(serviceId, true);
if (nonEmpty(shareInstances))
break;
} else {
shareInstances = new ArrayList<>();
for (String groupName : groupNames) {
List subShareInstances = namingService.selectInstances(serviceId, groupName, true);
if (nonEmpty(subShareInstances)) {
shareInstances.addAll(subShareInstances);
}
}
}
if (nonEmpty(shareInstances)) {
instances = shareInstances;
break;
}
}
return instances;
}
} 至此问题得以解决。
在 Nacos 上配置好共享 namespace 和 group 后，就能够进行跨命名空间访问了。
# nacos共享命名空间配置 示例
nacos.share.entities[0].namespace=e6ed2017-3ed6-4d9b-824a-db626424fc7b
nacos.share.entities[0].groupNames[0]=DEFAULT_GROUP
# 指定服务使用共享的负载均衡规则，service-id是注册到nacos上的服务id，ShareNacosNamespaceRule需要写全限定名
service-id.ribbon.NFLoadBalancerRuleClassName=***.***.***.ShareNacosNamespaceRule
注意：如果 Java 项目的 nacos discovery 版本用的是 2021.1，则不需要重写 Ribbon 的负载均衡类，因为该版本的 Nacos 不依赖 Ribbon。
2.2.1.RELEASE 版本的 nacos discovery 依赖 Ribbon.
2021.1 版本的 nacos discovery 不依赖 Ribbon。
四、总结
为了达到共享命名空间的预期，构思、查找资料、实现逻辑、调试，前后一共花费 4 天时间。成就感满满的同时，笔者也发现该功能仍存在共享服务缓存等可优化空间，留待后续实现。
五、参考文献
[1] Registration Center: Can services in different namespaces be called from each other? [EB/OL]. https://github.com/alibaba/na..., 2019-05-07/2022-11-29.
[2] 重写Nacos服务发现逻辑动态修改远程服务IP地址 [EB/OL]. https://www.cnblogs.com/chang..., 2021-04-08/2022-11-29.
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