At the moment it’s Google Cloud’s excellent Stackdriver product, probing a HTTP endpoint. Something like the
/-/healthy endpoint referenced in:
Add /-/ready and /-/healthy by iksaif · Pull Request #135 · prometheus/pushgateway
Also add the associated functions to one of the most important sub-system of the pushgateway: metric store. The http…
Prometheus itself is protected by HTTPS and HTTP basic auth.