我们的prometheus提供了来自入口控制器的以下3个指标，我试图了解这些指标之间的区别。
我的理解，
request_duration-在Nginx中达到请求到响应发送回客户端之间的时间。
ingress_upstream_latency-在上游服务器/ pod接受请求之前，在nginx中等待的时间。
response_duration-从后端容器/ pod获得响应的时间
# HELP nginx_ingress_controller_request_duration_seconds The request processing time in milliseconds
# TYPE nginx_ingress_controller_request_duration_seconds histogram
# HELP nginx_ingress_controller_ingress_upstream_latency_seconds Upstream service latency per Ingress
# TYPE nginx_ingress_controller_ingress_upstream_latency_seconds summary
# HELP nginx_ingress_controller_response_duration_seconds The time spent on receiving the response from the upstream server
# TYPE nginx_ingress_controller_response_duration_seconds histogram
因此，按照上述指标request_duration = ingress_upstream_latency + response_duration