上报自定义指标并同步到 Prometheus

<dependency>
    <groupId>io.opentelemetry</groupId>
    <artifactId>opentelemetry-api</artifactId>
    <version>1.35.0</version>
</dependency>

@RestController
@RequestMapping("/metric")
public class MetricController {
    // 把LongCounter作为成员变量
    private LongCounter httpRequestCounter;
    @PostConstruct
    public void init() {
        String scope = this.getClass().getName();
        // 获取OpenTelemetry对象
        OpenTelemetry openTelemetry = GlobalOpenTelemetry.get();
        // 获取Meter对象。关于Scope的定义，请参考OpenTelemetry官方文档，一般情况下，可以使用class全名
        Meter meter = openTelemetry.getMeter(scope);
        // 创建LongCounter对象。在项目中创建1次即可
        httpRequestCounter = meter.counterBuilder("http_request_total").setDescription("Counts HTTP request").build();
    }
}

@RestController
@RequestMapping("/metric")
public class MetricController {
    // 定义一个Key为method的属性标签
    private static final AttributeKey<String> METHOD_KEY = AttributeKey.stringKey("method");
    /*
    上个步骤中的初始化逻辑
    */
    @RequestMapping("/order")
    public String order() {
        // order请求数+1
        httpRequestCounter.add(1, Attributes.of(METHOD_KEY, "order"));
        return "order + 1";
    }
    @RequestMapping("/pay")
    public String pay() {
        // pay请求数+1
        httpRequestCounter.add(1, Attributes.of(METHOD_KEY, "pay"));
        return "pay + 1";
    }
}