SpringBoot Admin可以看作是Spring actuator 端點監控的一個UI界面，可以很方便的查看服務的運行情況。

部分服務不在線

如上圖，在項目整合了部分組件後，出現狀態顯示不在線，但應用還是能夠正常的對外提供服務。

• 我們知道 應用展示的在線狀態是讀取的 Spring actuator health endpoint數據

<code>curl http://127.0.0.1:5002/actuator/health

{"status":"DOWN"}  /<code>

• 此時無法通過 SpringBoot Admin 無法獲取更多的細節, 建議開發環境開啟端點的詳細信息。

<code>management:
  endpoints:
    web:
      exposure:
        include: '*'
  endpoint:
    health:
      show-details: always  #dev open/<code>

• 再次嘗試訪問, 輸出了全部組件的狀態，可以明確的看到由於 sentinel 狀態不對影響全局狀態為 down

<code>curl http://127.0.0.1:5002/actuator/health

{"status":"DOWN","components":{"discoveryComposite":{"status":"UP","components":{"discoveryClient":{"status":"UP","details":{"services":["pigx-upms-biz","pigx-tx-manager","pigx-daemon-elastic-job","pigx-mp-platform","pigx-daemon-quartz","pigx-gateway","pigx-auth","pigx-pay-platform","pigx-codegen","pigx-oa-platform","pigx-monitor"]}}}},"diskSpace":{"status":"UP","details":{"total":42927636480,"free":21334122496,"threshold":10485760}},"nacosConfig":{"status":"UP"},"nacosDiscovery":{"status":"UP"},"ping":{"status":"UP"},"reactiveDiscoveryClients":{"status":"UP","components":{"Simple Reactive Discovery Client":{"status":"UP","details":{"services":[]}}}},"redis":{"status":"UP","details":{"version":"5.0.7"}},"refreshScope":{"status":"UP"},"sentinel":{"status":"DOWN","details":{"dataSource":{},"enabled":true,"dashboard":{"description":"pigx-sentinel:5020 can't be connected","status":"DOWN"}}}}}/<code>

sentinel dashboadr can't be connected

• SentinelHealthIndicator.doHealthCheck 來看下 sentinel 的健康檢查是如何處理的

<code>protected void doHealthCheck(Health.Builder builder) throws Exception {
\tMap<string> detailMap = new HashMap<>();

\t\t// 獲取心跳發送器
\t\tHeartbeatSender heartbeatSender = HeartbeatSenderProvider
\t\t\t\t.getHeartbeatSender();
\t\t// 發送心跳
\t\tboolean result = heartbeatSender.sendHeartbeat();
\t\tif (result) {
\t\t   // 成功標記為UP
\t\t\tdetailMap.put("dashboard", Status.UP);
\t\t}
\t\telse {
\t\t    // 失敗 標記為down
\t\t\tdashboardUp = false;
\t\t\tdetailMap.put("dashboard", new Status(Status.DOWN.getCode(),
\t\t\t\t\tconsoleServer + " can't be connected"));
\t\t}
\t}

\t// If Dashboard and DataSource are both OK, the health status is UP
\tif (dashboardUp && dataSourceUp) {
\t\tbuilder.up().withDetails(detailMap);
\t}
\telse {
\t\tbuilder.down().withDetails(detailMap);
\t}
}/<string>/<code>

• SimpleHttpHeartbeatSender.sendHeartbeat 心跳發送器的處理邏輯

<code>public boolean sendHeartbeat() throws Exception {
\t
\t// 1. 判斷客戶端是和服務端是否交互 ，只有交互時dashboard 才有數據展示
\tif (TransportConfig.getRuntimePort() <= 0) {
\t\tRecordLog.info("[SimpleHttpHeartbeatSender] Runtime port not initialized, won't send heartbeat");
\t\treturn false;
\t}
\tInetSocketAddress addr = getAvailableAddress();
\tif (addr == null) {
\t\treturn false; 

\t}
\t
\t// 2. 訪問dashboard 的接口
\tSimpleHttpRequest request = new SimpleHttpRequest(addr, TransportConfig.getHeartbeatApiPath());
\trequest.setParams(heartBeat.generateCurrentMessage());
\tSimpleHttpResponse response = httpClient.post(request);
\tif (response.getStatusCode() == OK_STATUS) {
\t\treturn true;
\t}
\treturn false;
}/<code>

• 到底是上文代碼 第一步未交互被判斷為down、還是第二步訪問出錯判斷為down

查看 sentinel client 的日誌

<code>cat ~/csp/sentinel-record.log 

2020-03-23 13:54:04.634 INFO [SimpleHttpHeartbeatSender] Runtime port not initialized, won't send heartbeat  

/<code>

開始是第一步沒有初始化交互造成，服務判斷為 down

sentinel 如何初始化交互

• 初始化交互端口 commandCenter.start()

<code>public class CommandCenterInitFunc implements InitFunc {

    @Override
    public void init() throws Exception {
        CommandCenter commandCenter = CommandCenterProvider.getCommandCenter();

        if (commandCenter == null) {
            RecordLog.warn("[CommandCenterInitFunc] Cannot resolve CommandCenter");
            return;
        }
 

        commandCenter.beforeStart();
        // 開始初始化端口交互
        commandCenter.start();
        RecordLog.info("[CommandCenterInit] Starting command center: "
                + commandCenter.getClass().getCanonicalName());
    }
}/<code>

• 配置啟動立即加載初始化，而不是有流量請求再初始化

<code>public class SentinelAutoConfiguration {

\t@Value("${project.name:${spring.application.name:}}")
\tprivate String projectName;

\t@Autowired
\tprivate SentinelProperties properties;

\t@PostConstruct
\tprivate void init() {

\t\t// earlier initialize
\t\tif (properties.isEager()) {
\t\t\tInitExecutor.doInit();
\t\t}

\t}/<code>

<code>spring:
  application:
    name: @artifactId@
  cloud:
    sentinel:
      eager: true/<code>

作者：冷冷gg
鏈接：https://juejin.im/post/5e795b905188255e1e4ec1e3

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