nacos 注册中心之服务地址的查询

作者：周杰伦本人

2022 年 7 月 19 日
本文字数：4151 字
阅读完需：约 14 分钟

nacos 注册中心之服务地址的查询

nacos 的服务端给我们提供了获取注册中心中服务地址的查询 api，对应的 Open API 如下：

发送 get 请求

http://127.0.0.1:848/nacos/v1/ns/instance/list?serviceName=example

下载 nacos 服务端的源码，我们找到 InstanceController 类，有关实例的接口都在这个类中，我们从调用的 api 找到对应的 Controller 层

查询服务地址的方法是对应 InstanceController 的 list 方法：

InstanceController 的 list()方法

@GetMapping("/list")public JSONObject list(HttpServletRequest request) throws Exception {
    String namespaceId = WebUtils.optional(request, CommonParams.NAMESPACE_ID,        Constants.DEFAULT_NAMESPACE_ID);
    String serviceName = WebUtils.required(request, CommonParams.SERVICE_NAME);    String agent = WebUtils.getUserAgent(request);    String clusters = WebUtils.optional(request, "clusters", StringUtils.EMPTY);    String clientIP = WebUtils.optional(request, "clientIP", StringUtils.EMPTY);    Integer udpPort = Integer.parseInt(WebUtils.optional(request, "udpPort", "0"));    String env = WebUtils.optional(request, "env", StringUtils.EMPTY);    boolean isCheck = Boolean.parseBoolean(WebUtils.optional(request, "isCheck", "false"));
    String app = WebUtils.optional(request, "app", StringUtils.EMPTY);
    String tenant = WebUtils.optional(request, "tid", StringUtils.EMPTY);
    boolean healthyOnly = Boolean.parseBoolean(WebUtils.optional(request, "healthyOnly", "false"));
    return doSrvIPXT(namespaceId, serviceName, agent, clusters, clientIP, udpPort, env, isCheck, app, tenant,        healthyOnly);}

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解析请求参数，包括 namespaceId、服务名、代理、集群、客户端 ip 等等信息
通过 doSrvIPXT()方法返回服务列表数据

我们看一下 doSrvIPXT()方法中做了什么

doSrvIPXT()方法

doSrvIPXT()方法的主要功能是获取服务信息和所有的节点内容

public JSONObject doSrvIPXT(String namespaceId, String serviceName, String agent, String clusters, String clientIP,                            int udpPort,                            String env, boolean isCheck, String app, String tid, boolean healthyOnly)    throws Exception {
    ClientInfo clientInfo = new ClientInfo(agent);    JSONObject result = new JSONObject();    Service service = serviceManager.getService(namespaceId, serviceName);
    if (service == null) {        if (Loggers.SRV_LOG.isDebugEnabled()) {            Loggers.SRV_LOG.debug("no instance to serve for service: {}", serviceName);        }        result.put("name", serviceName);        result.put("clusters", clusters);        result.put("hosts", new JSONArray());        return result;    }
    checkIfDisabled(service);
    long cacheMillis = switchDomain.getDefaultCacheMillis();
    // now try to enable the push    try {        if (udpPort > 0 && pushService.canEnablePush(agent)) {            pushService.addClient(namespaceId, serviceName,                clusters,                agent,                new InetSocketAddress(clientIP, udpPort),                pushDataSource,                tid,                app);            cacheMillis = switchDomain.getPushCacheMillis(serviceName);        }    } catch (Exception e) {        Loggers.SRV_LOG.error("[NACOS-API] failed to added push client", e);        cacheMillis = switchDomain.getDefaultCacheMillis();    }
    List<Instance> srvedIPs;
    srvedIPs = service.srvIPs(Arrays.asList(StringUtils.split(clusters, ",")));
    // filter ips using selector:    if (service.getSelector() != null && StringUtils.isNotBlank(clientIP)) {        srvedIPs = service.getSelector().select(clientIP, srvedIPs);    }
    if (CollectionUtils.isEmpty(srvedIPs)) {
        if (Loggers.SRV_LOG.isDebugEnabled()) {            Loggers.SRV_LOG.debug("no instance to serve for service: {}", serviceName);        }
        if (clientInfo.type == ClientInfo.ClientType.JAVA &&            clientInfo.version.compareTo(VersionUtil.parseVersion("1.0.0")) >= 0) {            result.put("dom", serviceName);        } else {            result.put("dom", NamingUtils.getServiceName(serviceName));        }
        result.put("hosts", new JSONArray());        result.put("name", serviceName);        result.put("cacheMillis", cacheMillis);        result.put("lastRefTime", System.currentTimeMillis());        result.put("checksum", service.getChecksum());        result.put("useSpecifiedURL", false);        result.put("clusters", clusters);        result.put("env", env);        result.put("metadata", service.getMetadata());        return result;    }
    Map<Boolean, List<Instance>> ipMap = new HashMap<>(2);    ipMap.put(Boolean.TRUE, new ArrayList<>());    ipMap.put(Boolean.FALSE, new ArrayList<>());
    for (Instance ip : srvedIPs) {        ipMap.get(ip.isHealthy()).add(ip);    }
    if (isCheck) {        result.put("reachProtectThreshold", false);    }
    double threshold = service.getProtectThreshold();
    if ((float) ipMap.get(Boolean.TRUE).size() / srvedIPs.size() <= threshold) {
        Loggers.SRV_LOG.warn("protect threshold reached, return all ips, service: {}", serviceName);        if (isCheck) {            result.put("reachProtectThreshold", true);        }
        ipMap.get(Boolean.TRUE).addAll(ipMap.get(Boolean.FALSE));        ipMap.get(Boolean.FALSE).clear();    }
    if (isCheck) {        result.put("protectThreshold", service.getProtectThreshold());        result.put("reachLocalSiteCallThreshold", false);
        return new JSONObject();    }
    JSONArray hosts = new JSONArray();
    for (Map.Entry<Boolean, List<Instance>> entry : ipMap.entrySet()) {        List<Instance> ips = entry.getValue();
        if (healthyOnly && !entry.getKey()) {            continue;        }
        for (Instance instance : ips) {
            // remove disabled instance:            if (!instance.isEnabled()) {                continue;            }
            JSONObject ipObj = new JSONObject();
            ipObj.put("ip", instance.getIp());            ipObj.put("port", instance.getPort());            // deprecated since nacos 1.0.0:            ipObj.put("valid", entry.getKey());            ipObj.put("healthy", entry.getKey());            ipObj.put("marked", instance.isMarked());            ipObj.put("instanceId", instance.getInstanceId());            ipObj.put("metadata", instance.getMetadata());            ipObj.put("enabled", instance.isEnabled());            ipObj.put("weight", instance.getWeight());            ipObj.put("clusterName", instance.getClusterName());            if (clientInfo.type == ClientInfo.ClientType.JAVA &&                clientInfo.version.compareTo(VersionUtil.parseVersion("1.0.0")) >= 0) {                ipObj.put("serviceName", instance.getServiceName());            } else {                ipObj.put("serviceName", NamingUtils.getServiceName(instance.getServiceName()));            }
            ipObj.put("ephemeral", instance.isEphemeral());            hosts.add(ipObj);
        }    }
    result.put("hosts", hosts);    if (clientInfo.type == ClientInfo.ClientType.JAVA &&        clientInfo.version.compareTo(VersionUtil.parseVersion("1.0.0")) >= 0) {        result.put("dom", serviceName);    } else {        result.put("dom", NamingUtils.getServiceName(serviceName));    }    result.put("name", serviceName);    result.put("cacheMillis", cacheMillis);    result.put("lastRefTime", System.currentTimeMillis());    result.put("checksum", service.getChecksum());    result.put("useSpecifiedURL", false);    result.put("clusters", clusters);    result.put("env", env);    result.put("metadata", service.getMetadata());    return result;}

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代码虽然有点长，但内容非常好理解，主要做三件事：

调用 serviceManager.getService()方法根据传入的 namespaceId serviceName 获得 Service 实例，如果获得的实例为空，就打印没有相关实例的日志，并返回结果，如果 Service 实例不为空，执行下面的逻辑
检查 Service 是否禁用
试着开启推送，添加推送的客户端
从 Service 实例中调用 srvIPs 方法得到所有服务提供者的实例信息。
使用过滤器来获取到的实例信息
遍历组装 JSON 字符串并返回。