The expression browser is available at /graph on the Prometheus
server, allowing you to enter any expression and see its result
either in a table or graphed over time. This is primarily useful
for ad-hoc queries and debugging. For graphs, use Grafana or
Console templates.
The combination of Prometheus and Grafana is becoming a more and
more common monitoring stack used by DevOps teams for storing and
visualizing time series data. Prometheus acts as the storage
backend and Grafana as the interface for analysis and
visualization.
Alerting with Prometheus is separated into two parts. Alerting
rules in Prometheus servers send alerts to an Alertmanager. The
Alertmanager then manages those alerts, including silencing,
inhibition, aggregation and sending out notifications via methods
such as email, PagerDuty and HipChat.
Prometheus creates and sends alerts to the Alertmanager which then
sends notifications out to different receivers based on their
labels. A receiver can be one of many integrations including:
Slack, PagerDuty, email, or a custom integration via the generic
webhook interface.