单机模式的寻址模式很简单，其实就是找到自己的 IP:PORT 组合信息，然后格式化为⼀个节点信息， 调用 afterLookup 然后将信息存储到 ServerMemberManager 中。
public class StandaloneMemberLookup extends AbstractMemberLookup {
@Override
public void doStart() {
String url = InetUtils.getSelfIP() + ":" + EnvUtil.getPort();
afterLookup(MemberUtil.readServerConf(Collections.singletonList(url)));
}
@Override
public boolean useAddressServer() {
return false;
}
}
4.2文件寻址
文件寻址模式是 Nacos 集群模式下的默认寻址实现。文件寻址模式很简单，其实就是每个 Nacos 节点需要维护⼀个叫做 cluster.conf 的文件。
192.168.16.101:8847 192.168.16.102 192.168.16.103
该文件默认只需要填写每个成员节点的 IP 信息即可，端口会自动选择 Nacos 的默认端口 8848， 如过说有特殊需求更改了 Nacos 的端口信息，则需要在该文件将该节点的完整网路地址信息补充 完整（IP:PORT）。
当 Nacos 节点启动时，会读取该文件的内容，然后将文件内的 IP 解析为节点列表，调用 afterLookup 存入 ServerMemberManager 。
但是，这种默认寻址模式有⼀个缺点——运维成本较大，可以想象下，当你新增⼀个 Nacos 节点时， 需要去手动修改每个 Nacos 节点下的 cluster.conf 文件，这是多么辛苦的⼀件工作，或者稍微高 端⼀点，利用 ansible 等自动化部署的工具去推送 cluster.conf 文件去代替自己的手动操作，虽然说省去了较为繁琐的人工操作步骤，但是仍旧存在⼀个问题——每⼀个 Nacos 节点都存在⼀份 cluster.conf 文件，如果其中⼀个节点的 cluster.conf 文件修改失败，就造成了集群间成员节点列 表数据的不⼀致性，因此，又引申出了新的寻址模式——地址服务器寻址模式。
public class FileConfigMemberLookup extends AbstractMemberLookup {
private static final String DEFAULT_SEARCH_SEQ = "cluster.conf";
private FileWatcher watcher = new FileWatcher() {
@Override
public void onChange(FileChangeEvent event) {
readClusterConfFromDisk();
}
@Override
public boolean interest(String context) {
return StringUtils.contains(context, DEFAULT_SEARCH_SEQ);
}
};
@Override
public void doStart() throws NacosException {
readClusterConfFromDisk();
// Use the inotify mechanism to monitor file changes and automatically
// trigger the reading of cluster.conf
try {
WatchFileCenter.registerWatcher(EnvUtil.getConfPath(), watcher);
} catch (Throwable e) {
Loggers.CLUSTER.error("An exception occurred in the launch file monitor : {}", e.getMessage());
}
}
@Override
public boolean useAddressServer() {
return false;
}
@Override
public void destroy() throws NacosException {
WatchFileCenter.deregisterWatcher(EnvUtil.getConfPath(), watcher);
}
private void readClusterConfFromDisk() {
Collection tmpMembers = new ArrayList<>();
try {
List tmp = EnvUtil.readClusterConf();
tmpMembers = MemberUtil.readServerConf(tmp);
} catch (Throwable e) {
Loggers.CLUSTER
.error("nacos-XXXX [serverlist] failed to get serverlist from disk!, error : {}", e.getMessage());
}
afterLookup(tmpMembers);
}
}
如果发现集群扩缩容，那么就需要修改每个 Nacos 节点下的 cluster.conf 文件，然后 Nacos 内 部的文件变动监听中心会自动发现文件修改，重新读取文件内容、加载 IP 列表信息、更新新增的 节点。
private FileWatcher watcher = new FileWatcher() {
@Override
public void onChange(FileChangeEvent event) {
readClusterConfFromDisk();
}
@Override
public boolean interest(String context) {
return StringUtils.contains(context, DEFAULT_SEARCH_SEQ);
}
};
4.3地址服务器寻址
地址服务器寻址模式是 Nacos 官方推荐的⼀种集群成员节点信息管理，该模式利用了⼀个简易的 web 服务器，用于管理 cluster.conf 文件的内容信息，这样，运维人员只需要管理这⼀份集群成员 节点内容即可，而每个 Nacos 成员节点，只需要向这个 web 节点定时请求当前最新的集群成员节 点列表信息即可。
因此，通过地址服务器这种模式，大大简化了 Nacos 集群节点管理的成本，同时，地址服务器是 ⼀个非常简单的 web 程序，其程序的稳定性能够得到很好的保障。
public class AddressServerMemberLookup extends AbstractMemberLookup {
private final GenericType genericType = new GenericType() { };
public String domainName;
public String addressPort;
public String addressUrl;
public String envIdUrl;
public String addressServerUrl;
private volatile boolean isAddressServerHealth = true;
private int addressServerFailCount = 0;
private int maxFailCount = 12;
private final NacosRestTemplate restTemplate = HttpClientBeanHolder.getNacosRestTemplate(Loggers.CORE);
private volatile boolean shutdown = false;
private static final String HEALTH_CHECK_FAIL_COUNT_PROPERTY = "maxHealthCheckFailCount";
private static final String DEFAULT_HEALTH_CHECK_FAIL_COUNT = "12";
private static final String DEFAULT_SERVER_DOMAIN = "jmenv.tbsite.net";
private static final String DEFAULT_SERVER_POINT = "8080";
private static final int DEFAULT_SERVER_RETRY_TIME = 5;
private static final long DEFAULT_SYNC_TASK_DELAY_MS = 5_000L;
private static final String ADDRESS_SERVER_DOMAIN_ENV = "address_server_domain";
private static final String ADDRESS_SERVER_DOMAIN_PROPERTY = "address.server.domain";
private static final String ADDRESS_SERVER_PORT_ENV = "address_server_port";
private static final String ADDRESS_SERVER_PORT_PROPERTY = "address.server.port";
private static final String ADDRESS_SERVER_URL_ENV = "address_server_url";
private static final String ADDRESS_SERVER_URL_PROPERTY = "address.server.url";
private static final String ADDRESS_SERVER_RETRY_PROPERTY = "nacos.core.address-server.retry";
@Override
public void doStart() throws NacosException {
this.maxFailCount = Integer.parseInt(EnvUtil.getProperty(HEALTH_CHECK_FAIL_COUNT_PROPERTY, DEFAULT_HEALTH_CHECK_FAIL_COUNT));
initAddressSys();
run();
}
@Override
public boolean useAddressServer() {
return true;
}
private void initAddressSys() {
String envDomainName = System.getenv(ADDRESS_SERVER_DOMAIN_ENV);
if (StringUtils.isBlank(envDomainName)) {
domainName = EnvUtil.getProperty(ADDRESS_SERVER_DOMAIN_PROPERTY, DEFAULT_SERVER_DOMAIN);
} else {
domainName = envDomainName;
}
String envAddressPort = System.getenv(ADDRESS_SERVER_PORT_ENV);
if (StringUtils.isBlank(envAddressPort)) {
addressPort = EnvUtil.getProperty(ADDRESS_SERVER_PORT_PROPERTY, DEFAULT_SERVER_POINT);
} else {
addressPort = envAddressPort;
}
String envAddressUrl = System.getenv(ADDRESS_SERVER_URL_ENV);
if (StringUtils.isBlank(envAddressUrl)) {
addressUrl = EnvUtil.getProperty(ADDRESS_SERVER_URL_PROPERTY, EnvUtil.getContextPath() + "/" + "serverlist");
} else {
addressUrl = envAddressUrl;
}
addressServerUrl = "http://" + domainName + ":" + addressPort + addressUrl;
envIdUrl = "http://" + domainName + ":" + addressPort + "/env";
Loggers.CORE.info("ServerListService address-server port:" + addressPort);
Loggers.CORE.info("ADDRESS_SERVER_URL:" + addressServerUrl);
}
@SuppressWarnings("PMD.UndefineMagicConstantRule")
private void run() throws NacosException {
// With the address server, you need to perform a synchronous member node pull at startup
// Repeat three times, successfully jump out
boolean success = false;
Throwable ex = null;
int maxRetry = EnvUtil.getProperty(ADDRESS_SERVER_RETRY_PROPERTY, Integer.class, DEFAULT_SERVER_RETRY_TIME);
for (int i = 0; i < maxRetry; i++) {
try {
syncFromAddressUrl();
success = true;
break;
} catch (Throwable e) {
ex = e;
Loggers.CLUSTER.error("[serverlist] exception, error : {}", ExceptionUtil.getAllExceptionMsg(ex));
}
}
if (!success) {
throw new NacosException(NacosException.SERVER_ERROR, ex);
}
GlobalExecutor.scheduleByCommon(new AddressServerSyncTask(), DEFAULT_SYNC_TASK_DELAY_MS);
}
@Override
public void destroy() throws NacosException {
shutdown = true;
}
@Override
public Map info() {
Map info = new HashMap<>(4);
info.put("addressServerHealth", isAddressServerHealth);
info.put("addressServerUrl", addressServerUrl);
info.put("envIdUrl", envIdUrl);
info.put("addressServerFailCount", addressServerFailCount);
return info;
}
private void syncFromAddressUrl() throws Exception {
RestResult result = restTemplate
.get(addressServerUrl, Header.EMPTY, Query.EMPTY, genericType.getType());
if (result.ok()) {
isAddressServerHealth = true;
Reader reader = new StringReader(result.getData());
try {
afterLookup(MemberUtil.readServerConf(EnvUtil.analyzeClusterConf(reader)));
} catch (Throwable e) {
Loggers.CLUSTER.error("[serverlist] exception for analyzeClusterConf, error : {}",
ExceptionUtil.getAllExceptionMsg(e));
}
addressServerFailCount = 0;
} else {
addressServerFailCount++;
if (addressServerFailCount >= maxFailCount) {
isAddressServerHealth = false;
}
Loggers.CLUSTER.error("[serverlist] failed to get serverlist, error code {}", result.getCode());
}
}
class AddressServerSyncTask implements Runnable {
@Override
public void run() {
if (shutdown) {
return;
}
try {
syncFromAddressUrl();
} catch (Throwable ex) {
addressServerFailCount++;
if (addressServerFailCount >= maxFailCount) {
isAddressServerHealth = false;
}
Loggers.CLUSTER.error("[serverlist] exception, error : {}", ExceptionUtil.getAllExceptionMsg(ex));
} finally {
GlobalExecutor.scheduleByCommon(this, DEFAULT_SYNC_TASK_DELAY_MS);
}
}
}
}
