What is AlertManager?
The Alertmanager sends alerts to various channels like Slack or E-Mail.
Recall from part one that Prometheus creates an alert if something violates a rule. You can use the Alertmanager to silence and group alerts as well.
Configuration
You can get all source code from GitHub. Check out the tag `part-2-grafana` if you want to follow along.
docker-compose.yml
First of all, add the Alertmanager and a volume to docker-compose.yml:
alertmanager:
image: prom/alertmanager:v0.23.0
restart: unless-stopped
ports:
- "9093:9093"
volumes:
- "./alertmanager:/config"
- alertmanager-data:/data
command: --config.file=/config/alertmanager.yml --log.level=debug
volumes:
alertmanager-data:Alertmanager will persist silence configurations to the volume.
alertmanager/alertmanager.yml
This configuration contains information about which channels to send to. For simplicity, we use e-mail. Refer to the Alertmanager docs to learn about other channels.
Create a folder alertmanager and add a file alertmanager.yml to it:
route:
receiver: 'mail'
repeat_interval: 4h
group_by: [ alertname ]
receivers:
- name: 'mail'
email_configs:
- smarthost: 'smtp.gmail.com:465'
auth_username: 'your_mail@gmail.com'
auth_password: ""
from: 'your_mail@gmail.com'
to: 'some_mail@gmail.com'The `route` section configures which alerts will be sent. In our case, we sent all alerts. You could add more routes and filter, for example, on alert tags (see the example in the docs.).
receivers configures our target channels. Note how route refers to the receiver mail on line two. You will get a new mail every four hours until the problem is solved.
Connect to Prometheus
Finally, we need to tell Prometheus about the Alertmanager. Open prometheus/prometheus.yml and add the following:
alerting:
alertmanagers:
- scheme: http
static_configs:
- targets: [ 'alertmanager:9093' ]Testing
Run docker-compose up.
Open http://localhost:9093 in your browser to see the Alertmanager UI.
After a couple of minutes, the test alert fires. You can check this in your Prometheus instance.
Now, you can see the alert in the Alertmanager as well:
Check your inbox for the notification:
