Remote Write

3. Remote Write #

Forwarding data to Grafana Cloud or a local instance.

Metrics forwarding #

The prometheus.remote_write component takes the scraped metrics and pushes them to a compatible time series database, such as Grafana Mimir, Prometheus (with remote_write enabled), or Grafana Cloud. It handles authentication (Basic Auth, Bearer Token), buffering (WAL) to prevent data loss in case of a network outage, and compression.

Best Practice: Always configure the wal (Write-Ahead Log) component for your forwarders. This ensures that in the event of a database outage, Alloy caches the metrics on disk and automatically resends them once the connection is restored.

Common Mistake: Scraping metrics with high cardinality (e.g., including a user_id or a session_id in the labels of a Prometheus metric) without using relabel components to filter them. This will lead to a cardinality explosion and saturate your backend.

prometheus.remote_write "default" {
  endpoint {
    url = "https://prometheus-prod.grafana.net/api/prom/push"
  }
  wal {
    truncate_frequency = "2h"
    max_keepalive_time = "5m"
  }
}