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。
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]}
复制代码@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<Instance> 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<Instance> 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())));
}
}
复制代码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<Instance> selectInstances(String serviceName, List<String> clusters, boolean healthy) throws NacosException {
List<Instance> instances = super.selectInstances(serviceName, clusters, healthy);
instances.stream().forEach(instance -> instance.setIp("10.101.232.24"));
return instances;
}
}
}
复制代码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<ServiceInstance> getInstances(String serviceId) throws NacosException {
String group = discoveryProperties.getGroup();
List<Instance> 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<String> getServices() throws NacosException {
String group = discoveryProperties.getGroup();
ListView<String> services = discoveryProperties.namingServiceInstance()
.getServicesOfServer(1, Integer.MAX_VALUE, group);
return services.getData();
}
复制代码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。
/**
* <pre>
* @description: 共享nacos属性
* @author: rookie0peng
* @date: 2022/8/29 15:22
* </pre>
*/
@Configuration
@ConfigurationProperties(prefix = "nacos.share")
public class NacosShareProperties {
private final Map<String, Set<String>> NAMESPACE_TO_GROUP_NAME_MAP = new ConcurrentHashMap<>();
/**
* 共享nacos实体列表
*/
private List<NacosShareEntity> entities;
public List<NacosShareEntity> getEntities() {
return entities;
}
public void setEntities(List<NacosShareEntity> entities) {
this.entities = entities;
}
public Map<String, Set<String>> getNamespaceGroupMap() {
safeStream(entities).filter(entity -> nonNull(entity) && nonNull(entity.getNamespace()))
.forEach(entity -> {
Set<String> 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<String> groupNames;
public String getNamespace() {
return namespace;
}
public void setNamespace(String namespace) {
this.namespace = namespace;
}
public List<String> getGroupNames() {
return groupNames;
}
public void setGroupNames(List<String> groupNames) {
this.groupNames = groupNames;
}
@Override
public String toString() {
return "NacosShareEntity{" +
"namespace='" + namespace + ''' +
", groupNames=" + groupNames +
'}';
}
}
}
复制代码/**
* @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<String, NamingService> NAMESPACE_TO_NAMING_SERVICE_MAP = new ConcurrentHashMap<>();
public NacosDiscoveryPropertiesV2(NacosShareProperties nacosShareProperties) {
super();
this.nacosShareProperties = nacosShareProperties;
}
public Map<String, NamingService> shareNamingServiceInstances() {
if (!NAMESPACE_TO_NAMING_SERVICE_MAP.isEmpty()) {
return new HashMap<>(NAMESPACE_TO_NAMING_SERVICE_MAP);
}
List<NacosShareProperties.NacosShareEntity> 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;
}
}
复制代码/**
* @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<ServiceInstance> getInstances(String serviceId) throws NacosException {
String group = discoveryProperties.getGroup();
List<Instance> instances = discoveryProperties.namingServiceInstance()
.selectInstances(serviceId, group, true);
if (isEmpty(instances)) {
Map<String, Set<String>> namespaceGroupMap = nacosShareProperties.getNamespaceGroupMap();
Map<String, NamingService> namespace2NamingServiceMap = discoveryProperties.shareNamingServiceInstances();
for (Map.Entry<String, NamingService> entry : namespace2NamingServiceMap.entrySet()) {
String namespace;
NamingService namingService;
if (isNull(namespace = entry.getKey()) || isNull(namingService = entry.getValue()))
continue;
Set<String> groupNames = namespaceGroupMap.get(namespace);
List<Instance> shareInstances;
if (isEmpty(groupNames)) {
shareInstances = namingService.selectInstances(serviceId, group, true);
if (nonEmpty(shareInstances))
break;
} else {
shareInstances = new ArrayList<>();
for (String groupName : groupNames) {
List<Instance> 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<String> getServices() throws NacosException {
String group = discoveryProperties.getGroup();
ListView<String> services = discoveryProperties.namingServiceInstance()
.getServicesOfServer(1, Integer.MAX_VALUE, group);
return services.getData();
}
public static List<ServiceInstance> hostToServiceInstanceList(
List<Instance> instances, String serviceId) {
List<ServiceInstance> 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<String, String> 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());
}
}
复制代码/**
* @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);
}
}
复制代码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<Instance> instances = namingService.selectInstances(name, true);
if (CollectionUtils.isEmpty(instances)) {
LOGGER.warn("no instance in service {}, then to get share service's instance", name);
List<Instance> shareNamingService = this.getShareNamingService(name);
if (nonEmpty(shareNamingService))
instances = shareNamingService;
else
return null;
}
List<Instance> instancesToChoose = instances;
if (org.apache.commons.lang3.StringUtils.isNotBlank(clusterName)) {
List<Instance> 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<Instance> getShareNamingService(String serviceId) throws NacosException {
List<Instance> instances = Collections.emptyList();
Map<String, Set<String>> namespaceGroupMap = nacosShareProperties.getNamespaceGroupMap();
Map<String, NamingService> namespace2NamingServiceMap = nacosDiscoveryPropertiesV2.shareNamingServiceInstances();
for (Map.Entry<String, NamingService> entry : namespace2NamingServiceMap.entrySet()) {
String namespace;
NamingService namingService;
if (isNull(namespace = entry.getKey()) || isNull(namingService = entry.getValue()))
continue;
Set<String> groupNames = namespaceGroupMap.get(namespace);
List<Instance> shareInstances;
if (isEmpty(groupNames)) {
shareInstances = namingService.selectInstances(serviceId, true);
if (nonEmpty(shareInstances))
break;
} else {
shareInstances = new ArrayList<>();
for (String groupName : groupNames) {
List<Instance> subShareInstances = namingService.selectInstances(serviceId, groupName, true);
if (nonEmpty(subShareInstances)) {
shareInstances.addAll(subShareInstances);
}
}
}
if (nonEmpty(shareInstances)) {
instances = shareInstances;
break;
}
}
return instances;
}
}
复制代码至此问题得以解决。
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
复制代码注意：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 天左右。
但该功能仍然存在共享服务缓存等可优化空间，留待后续实现。
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