Traefik Reverse Proxy: Observability with Prometheus, Loki & Grafana

3 min
503 words
Categories: Monitoring
Tags: Traefik Prometheus Grafana Loki

Prerequisites

Traefik exposes metrics on EntryPoints, Routers, Services, and more. This post shows you how to collect these metrics with Prometheus and aggregate logs with Loki via Grafana Alloy for a complete monitoring solution.

Metrics

Add the following command flags to your Traefik docker-compose.yml:

docker-compose.yml
command:
  # ... existing commands ...
  - "--metrics.prometheus=true"
  - "--metrics.prometheus.addEntryPointsLabels=true"
  - "--metrics.prometheus.addRoutersLabels=true"
  - "--metrics.prometheus.addServicesLabels=true"

Re-create the Traefik container to apply the changes:

BASH
docker compose -f traefik/docker-compose.yml up -d --force-recreate

Verify metrics are available at http://<traefik-ip>:8080/metrics.

Configure Prometheus

Add a scrape job to your prometheus.yml:

prometheus.yml
scrape_configs:
  - job_name: 'traefik'
    scrape_interval: 5s
    static_configs:
      - targets: ['<traefik-ip>:8080']

Replace <traefik-ip> with your Traefik server’s IP address, then restart Prometheus:

BASH
docker restart prometheus

Verify Metrics

Query for Traefik metrics in Grafana’s Explore view:

PROMQL
traefik_router_requests_total

Log Files

Add the following command flags to your Traefik docker-compose.yml:

docker-compose.yml
command:
  # ... existing commands ...
  - "--accesslog=true"
  - "--accesslog.filepath=/log/access.log"
  - "--accesslog.format=json"
  - "--accesslog.fields.defaultmode=keep"
  - "--accesslog.fields.names.StartUTC=drop"
  - "--log.filepath=/log/traefik.log"
  - "--log.format=json"

Setting a filepath redirects logs to a file — they will no longer appear in docker logs.

Also add a volume mapping for the log directory:

docker-compose.yml
volumes:
  # ... existing volumes ...
  - /var/log/traefik:/log

Re-create the Traefik container:

BASH
docker compose -f traefik/docker-compose.yml up -d --force-recreate

Configure Grafana Alloy

Create a new Alloy config file for Traefik log collection:

BASH
nano alloy/config/traefik.alloy
traefik.alloy
// Traefik logs collection
local.file_match "traefik" {
  path_targets = [{
    __path__ = "/var/log/traefik/*.log",
  }]
}

loki.source.file "traefik" {
  targets    = local.file_match.traefik.targets
  forward_to = [loki.process.traefik.receiver]
}

loki.process "traefik" {
  stage.static_labels {
    values = {
      job = "traefik",
    }
  }
  forward_to = [loki.write.default.receiver]
}

Ensure your Alloy docker-compose.yml has /var/log mounted:

docker-compose.yml
volumes:
  - ./config/:/etc/alloy/config/:ro
  - /var/log:/var/log:ro
  - alloy-data:/var/lib/alloy/data

Restart Alloy to pick up the new configuration:

BASH
docker restart alloy

Verify Logs

Open the Alloy Web UI and confirm the loki.source.file component is healthy, then query in Grafana:

LOGQL
{job="traefik"}

Grafana Dashboard

You can use the pre-built Traefik Dashboard from GitHub, or explore available metrics from the official Traefik metrics overview .

License

Author: Sven van Ginkel

Link: https://svenvg.com/posts/traefik-reverse-proxy-observability-with-prometheus-loki-grafana/

License: CC BY-NC-SA 4.0

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Please attribute the source, use non-commercially, and maintain the same license.

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