FabledSteward/docs/plugins/traefik.md

Traefik Plugin

The Traefik plugin scrapes the Traefik reverse proxy's Prometheus /metrics endpoint on a configurable interval, stores per-router metrics, and surfaces them on the dashboard and a dedicated detail page.

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What It Does

On each scrape:

1. Fetches raw Prometheus text from the configured metrics_url
2. Parses histogram and counter data to compute per-router rates and latency approximations
3. Writes computed metrics to the traefik_metrics history table
4. Calls record_metric() for each metric, making them available to alert rules

Request rates and error rates are computed as deltas between the current and previous scrape, divided by elapsed time. Latency percentiles (p50, p95, p99) are approximated via linear interpolation over histogram buckets — these are estimates, not exact percentiles.

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Configuration

Key	Default	Description
metrics_url	http://localhost:8080/metrics	Traefik Prometheus endpoint
scrape_interval_seconds	60	How often to scrape

Enable the plugin by setting enabled: true in the app settings (Settings UI or directly in app_settings DB table under key plugin.traefik).

Traefik must have metrics enabled. In Traefik config:

# traefik.yml
metrics:
  prometheus: {}

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Metrics Collected

Per Traefik router, per scrape:

Metric name	Description
request_rate	Requests per second (delta from previous scrape)
error_rate_4xx_pct	4xx responses as % of total requests
error_rate_5xx_pct	5xx responses as % of total requests
latency_p50_ms	Approximate p50 latency (ms)
latency_p95_ms	Approximate p95 latency (ms)
latency_p99_ms	Approximate p99 latency (ms)

All metrics are available for alert rules with source_module = "traefik" and resource_name = <router name>.

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Alert Rule Examples

Rule	source_module	resource_name	metric_name	operator	threshold
High 5xx rate on API router	traefik	api@docker	error_rate_5xx_pct	>	1.0
Slow API (p95 > 500ms)	traefik	api@docker	latency_p95_ms	>	500
Traffic spike	traefik	web@docker	request_rate	>	1000

Router names are the Traefik router labels as reported in the Prometheus metrics (e.g. api@docker, dashboard@internal). Check the raw metrics at your metrics_url to see the exact names in use.

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UI

Dashboard Widget

The widget appears on the dashboard when the Traefik plugin is enabled. It shows, per router:

• Router name
• Current req/s
• p95 latency (color-coded: green < 200ms, yellow < 500ms, red ≥ 500ms)
• 5xx error rate (shown only if > 0)

The widget auto-refreshes via HTMX polling every poll_interval seconds. Fragment endpoint: GET /plugins/traefik/widget.

Detail Page

The full Traefik page at /plugins/traefik/ shows all routers with sparkline history charts (last 20 data points) for request rate, p95 latency, and 5xx error rate.

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File Locations

File	Purpose
plugins/traefik/__init__.py	Plugin entry point: setup(), get_scheduled_tasks(), get_blueprint()
plugins/traefik/plugin.yaml	Plugin metadata and default config
plugins/traefik/models.py	TraefikMetric SQLAlchemy model
plugins/traefik/scheduler.py	make_scrape_task() and scrape logic
plugins/traefik/scraper.py	Prometheus text parsing and metric computation
plugins/traefik/routes.py	GET / (detail page) and GET /widget (HTMX fragment)
plugins/traefik/migrations/	Alembic migration for traefik_metrics table
plugins/traefik/templates/traefik/	index.html (detail) and widget.html (dashboard fragment)

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Database Table

traefik_metrics (defined in plugins/traefik/models.py):

Column	Type	Description
id	UUID	Primary key
router_name	str	Traefik router name
scraped_at	timestamp UTC	When this row was written
request_rate	float	req/s
error_rate_4xx_pct	float	% 4xx
error_rate_5xx_pct	float	% 5xx
latency_p50_ms	float	Approx p50 (ms)
latency_p95_ms	float	Approx p95 (ms)
latency_p99_ms	float	Approx p99 (ms)