Tutorial Beginner By Samson Tanimawo, PhD Published Oct 5, 2026 10 min read

Prometheus + Alertmanager: 30-Minute Tutorial

From zero to alerts firing into Slack. Covered in detail: install, instrumentation, alert rule, routing.

Step 1: Run Prometheus

docker run -d -p 9090:9090 -v $PWD/prometheus.yml:/etc/prometheus/prometheus.yml prom/prometheus

Open localhost:9090.

Step 2: Instrument app

Add a metrics endpoint to your app (Prometheus client lib).
Configure scrape in prometheus.yml.
Reload: kill -HUP $(pidof prometheus).

Step 3: Write alert rule

Create alerts.yml with rule. Reference in prometheus.yml.

Reload Prometheus.

Verify in localhost:9090/alerts.

Step 4: Route to Slack

Run Alertmanager: docker run -d -p 9093:9093 prom/alertmanager

Configure Slack webhook in alertmanager.yml.

Trigger alert; verify in Slack.

Antipatterns

Default scrape interval. Tune for your workload.
No alert rule expiry. Pages forever.
Alertmanager without grouping. Spam during cascade.

What to do this week

Three moves. (1) Run the tutorial end-to-end on your own laptop / sandbox. (2) Apply the pattern to one production workload. (3) Document the variations you needed; share with the team.