Using the expression browser
Let us explore data that Prometheus has collected about itself. To
use Prometheus's built-in expression browser, navigate tohttp://localhost:9090/queryand choose the "Graph" tab.
As you can gather fromlocalhost:9090/metrics,
one metric that Prometheus exports about itself is namedprometheus_target_interval_length_seconds(the actual amount of time between
target scrapes). Enter the below into the expression console and then click "Execute":
prometheus_target_interval_length_seconds
This should return a number of different time series (along with the latest value
recorded for each), each with the metric nameprometheus_target_interval_length_seconds, but with different labels. These
labels designate different latency percentiles and target group intervals.
If we are interested only in 99th percentile latencies, we could use this
query:
prometheus_target_interval_length_seconds{quantile="0.99"}