Alertmanager

Alertmanager is a component of the Prometheus monitoring system designed to manage alert notifications. It does not collect metrics; instead it receives alerts from Prometheus servers or other producers, deduplicates and groups them, and routes notifications to configured receivers. It also handles silences and inhibition rules to reduce noise.

Operation: It runs as a standalone service and exposes an API for receiving alerts. Alerts are processed according to a configuration file called alertmanager.yaml, which defines routes, receivers, and grouping policies. Routing is based on alert labels and can group related alerts into a single notification.

Features: Notable features include deduplication, grouping by labels, inhibition rules, and silences. Alertmanager supports multiple receiver types such as email, Slack, PagerDuty, Opsgenie, VictorOps, and webhooks. Messages can be templated; a web UI and API provide visibility and control over alerts.

Deployment and use: In practice, Alertmanager is deployed alongside Prometheus, often in Kubernetes environments managed by the Prometheus Operator. It centralizes alert delivery, supports high availability, and exposes metrics for its own health and performance.

History and licensing: Alertmanager originated at SoundCloud as part of the early Prometheus project and has since become a core component of the Prometheus ecosystem. It is open source, under the Apache 2.0 license, and maintained by the Prometheus project within the Cloud Native Computing Foundation ecosystem.