spring cloud alibaba 应用无法注册到sentinel dashboard-编程知识

一。技术背景

由于升级jdk17的需要我们将项目中的 spring cloud spring cloud alibaba 以及springboot进行了升级各版本如下
spring cloud 2021.0.5
spring cloud alibaba 2021.0.5.0
spring boot 2.6.13

二。问题表现

当启动项目服务后，服务无法注册到 sentinel-dashboard

三。错误排查

首先检查sentinel-dashboard 启动状态启动成功并且可以正常访问且不存在网络问题
环境配置检查

<!-- 依赖检查 无误 -->
<dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-gateway</artifactId>
</dependency><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
</dependency><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-alibaba-sentinel-gateway</artifactId>
</dependency>

配置检查

#配置也正常
spring.cloud.sentinel.transport.dashboard=localhost:8080
spring.cloud.sentinel.transport.port=8719

第三步源码追踪

接下来开始漫长源码分析步骤

然后点击 spring.cloud.sentinel.transport.dashboard 这条配置跳转 com.alibaba.cloud.sentinel.SentinelProperties.Transport#setDashboard

然后点击 getDashboard() 方法查看在哪里调用最后来到了 com.alibaba.cloud.sentinel.custom.SentinelAutoConfiguration#init

在如下代码中

@Configuration(proxyBeanMethods = false)
@ConditionalOnProperty(name = "spring.cloud.sentinel.enabled", matchIfMissing = true)
@EnableConfigurationProperties(SentinelProperties.class)
public class SentinelAutoConfiguration {@PostConstructprivate void init() {///省略部分逻辑	if (StringUtils.isEmpty(System.getProperty(TransportConfig.SERVER_PORT))&& StringUtils.isNotBlank(properties.getTransport().getPort())) {System.setProperty(TransportConfig.SERVER_PORT,properties.getTransport().getPort());}if (StringUtils.isEmpty(System.getProperty(TransportConfig.CONSOLE_SERVER))&& StringUtils.isNotBlank(properties.getTransport().getDashboard())) {System.setProperty(TransportConfig.CONSOLE_SERVER,properties.getTransport().getDashboard());}}
}

断点时发现配置成功被设置到系统的属性配置中
接下来再来看心跳发送具体类 HeartbeatSenderInitFunc
com.alibaba.csp.sentinel.transport.init.HeartbeatSenderInitFunc#init

@Override
public void init() {HeartbeatSender sender = HeartbeatSenderProvider.getHeartbeatSender();if (sender == null) {RecordLog.warn("[HeartbeatSenderInitFunc] WARN: No HeartbeatSender loaded");return;}initSchedulerIfNeeded();long interval = retrieveInterval(sender);setIntervalIfNotExists(interval);//定时调度发送心跳scheduleHeartbeatTask(sender, interval);
}

具体得调度逻辑每5秒发送一次心跳

private void scheduleHeartbeatTask(/*@NonNull*/ final HeartbeatSender sender, /*@Valid*/ long interval) {pool.scheduleAtFixedRate(new Runnable() {@Overridepublic void run() {try {sender.sendHeartbeat();} catch (Throwable e) {RecordLog.warn("[HeartbeatSender] Send heartbeat error", e);}}}, 5000, interval, TimeUnit.MILLISECONDS);RecordLog.info("[HeartbeatSenderInit] HeartbeatSender started: "+ sender.getClass().getCanonicalName());
}

我们再来看下具体的实现
sender.sendHeartbeat();
实现类只有一个 SimpleHttpHeartbeatSender

com.alibaba.csp.sentinel.transport.heartbeat.SimpleHttpHeartbeatSender#sendHeartbeat

@Override                                                                                                     
public boolean sendHeartbeat() throws Exception {                                                             if (TransportConfig.getRuntimePort() <= 0) {                                                              RecordLog.info("[SimpleHttpHeartbeatSender] Command server port not initialized, won't send heartbeat"return false;                                                                                         }                                                                                                         Endpoint addrInfo = getAvailableAddress();                                                                if (addrInfo == null) {                                                                                   return false;                                                                                         }                                                                                                         SimpleHttpRequest request = new SimpleHttpRequest(addrInfo, TransportConfig.getHeartbeatApiPath());       request.setParams(heartBeat.generateCurrentMessage());                                                    try {                                                                                                     SimpleHttpResponse response = httpClient.post(request);                                               if (response.getStatusCode() == OK_STATUS) {                                                          return true;                                                                                      } else if (clientErrorCode(response.getStatusCode()) || serverErrorCode(response.getStatusCode())) {  RecordLog.warn("[SimpleHttpHeartbeatSender] Failed to send heartbeat to " + addrInfo              + ", http status code: " + response.getStatusCode());                                         }                                                                                                     } catch (Exception e) {                                                                                   RecordLog.warn("[SimpleHttpHeartbeatSender] Failed to send heartbeat to " + addrInfo, e);             }                                                                                                         return false;                                                                                             
}

以上就是发送心跳的逻辑
核心逻辑

获取有效的链接
创建连接发送心跳请求
响应以及异常处理

但是在断点过程中有效的链接列表居然是空的这就是导致代码无法继续向下
在这里插入图片描述
然后我们继续围绕这个点进行排查

获取有效的地址列表方法如下

private Endpoint getAvailableAddress() {if (addressList == null || addressList.isEmpty()) {return null;}if (currentAddressIdx < 0) {currentAddressIdx = 0;}int index = currentAddressIdx % addressList.size();return addressList.get(index);
}

发现使用的成员变量 addressList 我们再来找下这个值的赋值操作

赋值操作只有一个地方在SimpleHttpHeartbeatSender的构造方法中

public SimpleHttpHeartbeatSender() {// Retrieve the list of default addresses.List<Endpoint> newAddrs = TransportConfig.getConsoleServerList();if (newAddrs.isEmpty()) {RecordLog.warn("[SimpleHttpHeartbeatSender] Dashboard server address not configured or not available");} else {RecordLog.info("[SimpleHttpHeartbeatSender] Default console address list retrieved: {}", newAddrs);}this.addressList = newAddrs;
}

com.alibaba.csp.sentinel.transport.config.TransportConfig#getConsoleServerList

public static List<Endpoint> getConsoleServerList() {String config = SentinelConfig.getConfig(CONSOLE_SERVER);List<Endpoint> list = new ArrayList<Endpoint>();if (StringUtil.isBlank(config)) {return list;}//。。。。。省略部分return list;
}

com.alibaba.csp.sentinel.config.SentinelConfig#getConfig(java.lang.String)

public static String getConfig(String key) {AssertUtil.notNull(key, "key cannot be null");return props.get(key);
}

我们再来看下 props的初始化

在SentinelConfig的静态构造中

static {try {initialize();//加载配置loadProps();resolveAppName();resolveAppType();RecordLog.info("[SentinelConfig] Application type resolved: {}", appType);} catch (Throwable ex) {RecordLog.warn("[SentinelConfig] Failed to initialize", ex);ex.printStackTrace();}
}

com.alibaba.csp.sentinel.config.SentinelConfig#loadProps

private static void loadProps() {///从配置加载中获取配置Properties properties = SentinelConfigLoader.getProperties();for (Object key : properties.keySet()) {setConfig((String) key, (String) properties.get(key));}
}

从SentinelConfigLoader 获取到配置

public static Properties getProperties() {return properties;
}

而这个properties的初始化是在SentinelConfigLoader 静态构造方法中

static {try {load();} catch (Throwable t) {RecordLog.warn("[SentinelConfigLoader] Failed to initialize configuration items", t);}
}

private static void load() {// Order: system property -> system env -> default file (classpath:sentinel.properties) -> legacy pathString fileName = System.getProperty(SENTINEL_CONFIG_PROPERTY_KEY);if (StringUtil.isBlank(fileName)) {fileName = System.getenv(SENTINEL_CONFIG_ENV_KEY);if (StringUtil.isBlank(fileName)) {fileName = DEFAULT_SENTINEL_CONFIG_FILE;}}Properties p = ConfigUtil.loadProperties(fileName);if (p != null && !p.isEmpty()) {RecordLog.info("[SentinelConfigLoader] Loading Sentinel config from {}", fileName);properties.putAll(p);}for (Map.Entry<Object, Object> entry : new CopyOnWriteArraySet<>(System.getProperties().entrySet())) {String configKey = entry.getKey().toString();String newConfigValue = entry.getValue().toString();String oldConfigValue = properties.getProperty(configKey);properties.put(configKey, newConfigValue);if (oldConfigValue != null) {RecordLog.info("[SentinelConfigLoader] JVM parameter overrides {}: {} -> {}",configKey, oldConfigValue, newConfigValue);}}
}

看到这里就大概明白了，因为这是静态代码话肯定优先初始化，而我们的地址在项目启动bean加载中才会设置到System的Properties里

所以获取的地址一直是空的。也无法注册到sentinel-dashboard上

四。解决办法

idea 启动类增加参数指定dashboard server地址以及应用名称

-Dcsp.sentinel.dashboard.server=localhost:8080 -Dcsp.sentinel.app.name=gateway-service

启动类设置系统变量

@SpringBootApplication
@EnableDiscoveryClient
public class GatewayServiceApplication {public static void main(String[] args) {System.setProperty("csp.sentinel.dashboard.server","localhost:8080");System.setProperty("csp.sentinel.app.name","gateway-service");SpringApplication.run(GatewayServiceApplication.class, args);}}