Prometheus is an open-source systems monitoring and alerting toolkit originally built at SoundCloud. It is designed to record real-time metrics in a time-series database, built using a highly dimensional data model. Prometheus is a powerful tool for monitoring applications and infrastructure, providing insights into system performance and health.
For more information, you can visit the official Prometheus website.
One common issue users encounter is that Prometheus does not send alerts as expected. This can be frustrating, especially when relying on alerts to notify you of critical system issues. The symptom is typically observed when expected alerts are not received, despite being configured in Prometheus.
The root cause of Prometheus not sending alerts often lies in misconfigured alerting rules or issues with Alertmanager integration. Alerting rules define the conditions under which alerts are triggered, and Alertmanager handles the delivery of these alerts. If either is misconfigured, alerts may not be sent.
To understand more about alerting rules, refer to the Prometheus Alerting Rules documentation.
First, check your alerting rules to ensure they are correctly defined. You can find these rules in the Prometheus configuration file, typically named prometheus.yml. Ensure that the syntax is correct and that the conditions for triggering alerts are appropriate.
groups:
- name: example
rules:
- alert: InstanceDown
expr: up == 0
for: 5m
labels:
severity: critical
annotations:
summary: "Instance {{ $labels.instance }} down"
For more details, visit the Prometheus Configuration documentation.
Ensure that Alertmanager is properly configured and running. Check the alertmanager.yml file for correct routing and receiver configurations. Make sure Alertmanager is reachable from Prometheus.
route:
receiver: 'team-X-mails'
receivers:
- name: 'team-X-mails'
email_configs:
- to: '[email protected]'
For more information, refer to the Alertmanager documentation.
Use the Prometheus web UI to test your alerting rules. Navigate to the 'Alerts' section and check if the rules are firing as expected. You can also use the 'Graph' section to manually evaluate the expressions used in your alerting rules.
Check the logs of both Prometheus and Alertmanager for any errors or warnings that might indicate configuration issues. Logs can provide valuable insights into what might be going wrong.
By following these steps, you should be able to diagnose and resolve issues related to Prometheus not sending alerts. Ensuring that both alerting rules and Alertmanager configurations are correct is crucial for the effective functioning of your monitoring setup.
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