监控插件（二）prometheus（2）API Counter&&Gauge

综述

一、Counter

错误写法

Counter.builder("api_request_total")
                    .description("Total number of API requests")
                    .tag("uri", request.getRequestURI())
                    .tag("method", request.getMethod())
                    .tag("status", String.valueOf(responseWrapper.getStatus()))
                    .register(meterRegistry)
                    .increment();

jakarta.servlet.ServletException: Request processing failed: java.lang.IllegalArgumentException: Failed to register Collector of type MicrometerCollector: repository_method_list_elements_sum is already in use by another Collector of type MicrometerCollector
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1022) ~[spring-webmvc-6.1.5.jar:6.1.5]
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:914) ~[spring-webmvc-6.1.5.jar:6.1.5]
 

不应该重复注册，正确写法：

 Counter requestCounter = meterRegistry.find("api_request_total")
                    .tag("uri", request.getRequestURI())
                    .tag("method", request.getMethod())
                    .tag("status", String.valueOf(responseWrapper.getStatus()))
                    .counter();
            if (requestCounter == null) {
                requestCounter = Counter.builder("api_request_total")
                        .description("Total number of API requests")
                        .tag("uri", request.getRequestURI())
                        .tag("method", request.getMethod())
                        .tag("status", String.valueOf(responseWrapper.getStatus()))
                        .register(meterRegistry);
            }
            requestCounter.increment();

二、Gauge