25、SpringCloud Alibaba - nacos 服务地址动态更新
前言
通过配置endpoint来实现服务地址的动态更新。
服务地址动态更新
1、 在NacosConfigBootstrapConfiguration创建NacosConfigManager的过程中，会创建NacosConfigService；
NacosConfigBootstrapConfiguration.java
@Bean
@ConditionalOnMissingBean
public NacosConfigManager nacosConfigManager(
NacosConfigProperties nacosConfigProperties) {
return new NacosConfigManager(nacosConfigProperties);
}
2、 NacosConfigManager；
public NacosConfigManager(NacosConfigProperties nacosConfigProperties) {
this.nacosConfigProperties = nacosConfigProperties;
// Compatible with older code in NacosConfigProperties,It will be deleted in the
// future.
//创建 NacosConfigService
createConfigService(nacosConfigProperties);
}
3、 createConfigService()；
static ConfigService createConfigService(
NacosConfigProperties nacosConfigProperties) {
if (Objects.isNull(service)) {
synchronized (NacosConfigManager.class) {
try {
if (Objects.isNull(service)) {
//创建 NacosConfigService
service = NacosFactory.createConfigService(
nacosConfigProperties.assembleConfigServiceProperties());
}
}
catch (NacosException e) {
log.error(e.getMessage());
throw new NacosConnectionFailureException(
nacosConfigProperties.getServerAddr(), e.getMessage(), e);
}
}
}
return service;
}
public static ConfigService createConfigService(Properties properties) throws NacosException {
return ConfigFactory.createConfigService(properties);
}
使用反射创建 NacosConfigService
public static ConfigService createConfigService(Properties properties) throws NacosException {
try {
Class<?> driverImplClass = Class.forName("com.alibaba.nacos.client.config.NacosConfigService");
Constructor constructor = driverImplClass.getConstructor(Properties.class);
ConfigService vendorImpl = (ConfigService) constructor.newInstance(properties);
return vendorImpl;
} catch (Throwable e) {
throw new NacosException(NacosException.CLIENT_INVALID_PARAM, e);
}
}
4、 NacosConfigService；
public NacosConfigService(Properties properties) throws NacosException {
ValidatorUtils.checkInitParam(properties);
String encodeTmp = properties.getProperty(PropertyKeyConst.ENCODE);
if (StringUtils.isBlank(encodeTmp)) {
this.encode = Constants.ENCODE;
} else {
this.encode = encodeTmp.trim();
}
// 初始化命名空间
initNamespace(properties);
// 与nacos服务端交互的http请求代理
this.agent = new MetricsHttpAgent(new ServerHttpAgent(properties));
//启动定时任务更新服务地址
this.agent.start();
// 创建ClientWorker，用于定时更新配置
this.worker = new ClientWorker(this.agent, this.configFilterChainManager, properties);
}
5、 agent.start()；
public void start() throws NacosException {
httpAgent.start();
}
public void start() throws NacosException {
serverListMgr.start();
}
public synchronized void start() throws NacosException {
//是否已经启动，
//或者服务列表时固定的，即配置了serverAddr，不配置serverAddr并配置endpoint时，可以从endpoint获取
if (isStarted || isFixed) {
return;
}
//获取服务列表任务
GetServerListTask getServersTask = new GetServerListTask(addressServerUrl);
//没有获取到服务列表，会进行重试
for (int i = 0; i < initServerlistRetryTimes && serverUrls.isEmpty(); ++i) {
//执行任务
getServersTask.run();
try {
this.wait((i + 1) * 100L);
} catch (Exception e) {
LOGGER.warn("get serverlist fail,url: {}", addressServerUrl);
}
}
if (serverUrls.isEmpty()) {
LOGGER.error("[init-serverlist] fail to get NACOS-server serverlist! env: {}, url: {}", name,
addressServerUrl);
throw new NacosException(NacosException.SERVER_ERROR,
"fail to get NACOS-server serverlist! env:" + name + ", not connnect url:" + addressServerUrl);
}
// executor schedules the timer task
//延时 30s 调度 getServersTask
this.executorService.scheduleWithFixedDelay(getServersTask, 0L, 30L, TimeUnit.SECONDS);
isStarted = true;
}
6、 GetServerListTask；
class GetServerListTask implements Runnable {
final String url;
GetServerListTask(String url) {
this.url = url;
}
@Override
public void run() {
/*
get serverlist from nameserver
*/
try {
//更新服务列表
updateIfChanged(getApacheServerList(url, name));
} catch (Exception e) {
LOGGER.error("[" + name + "][update-serverlist] failed to update serverlist from address server!", e);
}
}
}
7、 getApacheServerList()；
private List<String> getApacheServerList(String url, String name) {
try {
//通过http请求获取服务列表
HttpRestResult<String> httpResult = nacosRestTemplate.get(url, Header.EMPTY, Query.EMPTY, String.class);
if (httpResult.ok()) {
if (DEFAULT_NAME.equals(name)) {
EnvUtil.setSelfEnv(httpResult.getHeader().getOriginalResponseHeader());
}
//解析服务列表
List<String> lines = IoUtils.readLines(new StringReader(httpResult.getData()));
List<String> result = new ArrayList<String>(lines.size());
for (String serverAddr : lines) {
if (StringUtils.isNotBlank(serverAddr)) {
String[] ipPort = IPUtil.splitIPPortStr(serverAddr.trim());
String ip = ipPort[0].trim();
if (ipPort.length == 1) {
result.add(ip + IPUtil.IP_PORT_SPLITER + ParamUtil.getDefaultServerPort());
} else {
result.add(serverAddr);
}
}
}
return result;
} else {
LOGGER.error("[check-serverlist] error. addressServerUrl: {}, code: {}", addressServerUrl,
httpResult.getCode());
return null;
}
} catch (Exception e) {
LOGGER.error("[check-serverlist] exception. url: " + url, e);
return null;
}
}
8、 updateIfChanged()；
private void updateIfChanged(List<String> newList) {
if (null == newList || newList.isEmpty()) {
LOGGER.warn("[update-serverlist] current serverlist from address server is empty!!!");
return;
}
List<String> newServerAddrList = new ArrayList<String>();
for (String server : newList) {
if (server.startsWith(HTTP) || server.startsWith(HTTPS)) {
newServerAddrList.add(server);
} else {
newServerAddrList.add(HTTP + server);
}
}
/*
no change
*/
if (newServerAddrList.equals(serverUrls)) {
return;
}
//更新服务列表
serverUrls = new ArrayList<String>(newServerAddrList);
//服务列表迭代器
iterator = iterator();
//第一个服务地址
currentServerAddr = iterator.next();
// Using unified event processor, NotifyCenter
//发布服务列表变化事件 ServerlistChangeEvent
NotifyCenter.publishEvent(new ServerlistChangeEvent());
LOGGER.info("[{}] [update-serverlist] serverlist updated to {}", name, serverUrls);
}