肯请指教
Request Rate

求 http simulator 的总体请求率 (1分钟滚动窗口)
  sum(rate(http_requests_total{job="http"}[1m]))

求 每分钟多少是错误请求
  http_requests_total{job="http",status="500"} - http_requests_total{job="http",status="500"} offset 1m

求对 /users 端点的错误请求率
  rate(http_requests_total{job="http",endpoint="/users",status="500"}[1m])

Latency distribution

求 延迟中位数
  histogram_quantile(0.5, http_request_duration_milliseconds_bucket)

求 错误请求的 90 百分位延迟，按端点分组
  sort_desc(
    histogram_quantile(0.9, sum by (endpoint, le) (http_request_duration_milliseconds_bucket{status="500"}) )
  )

对 /users 端点的请求延迟 ，是否满足3个9都在400ms以内的 SLO
  histogram_quantile(0.999, sum by (le) (http_request_duration_milliseconds_bucket{endpoint="/users"}))