Internal Backstage API
GET http://unleash.host.com/internal-backstage/prometheus
Unleash uses Prometheus internally to collect metrics. By default, the metrics are available at /internal-backstage/prometheus. You can disable this endpoint by setting the serverMetrics option to false.
Note that it's not recommended to expose Prometheus metrics to the public as of the Prometheus pentest-report issue PRM-01-002. Thus, if you want to keep metrics enabled, you should block all external access to /internal-backstage/* on the network layer to keep your instance secure.
Annotations
Unleash will automatically count all updates for all flags under the metric name feature_toggle_update_total, and the flag name is will be set as a label value. This information can be used to create annotations in grafana for everytime a feature flag is changed.
You can use this query in grafana to achieve this:
delta(feature_toggle_update_total{toggle="Demo"}[1m]) != bool 0
Another useful counter is the feature_toggle_usage_total which will give you the numbers for how many times a feature flag has been evaluated to active or not.