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Monitoring

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James Brucker edited this page Dec 22, 2025 · 10 revisions

We want to remotely monitor the health, activity, and related metrics of

  • back-end application code
  • web server, e.g. Nginx (production) or Uvicorn (development)
  • database
  • front-end

For the first three items, we use Prometheus for metrics and Grafana for visual display of the data.

Monitoring Components and URLs

Component Monitor URL
FastAPI WS prometheus-fastapi-instrumentor + custom code in main.py http://localhost:8000/metrics
Nginx /nginx_status location invoked Nginx's stub_status module for metrics. For security, accessible only inside Docker network http://nginx:8080/nginx_status
Nginx Exporter nginx-exporter collects and adapts Nginx data for Prometheus http://nginx-exporter:9113/metrics
Prometheus Server Collects & records metrics. Paths: /metrics, /targets, /query http://localhost:9090
Grafana UI Grafana visualizer for Prometheus and other services http://localhost:4000

Note that Docker uses an internal DNS to resolve container names like nginx to IP addresses. Use docker network ls to discover network names, docker network inspect homelog_default to discover container IP addresses.

To verify a container name (nginx-exporter) is being resolved to an internal IP address:

docker exec -it nginx nslookup nginx-exporter

As of this writing, the relevant files and directories are:

project/
├── docker-compose.yml    Configure containers, exposed ports, and volumes
├── backend/
│   ├── Dockerfile        FastAPI web service + Uvicorn
│   └── main.py           Configure and expose metrics for Prometheus
├── nginx/                Nginx proxies the backend web service
│   └── nginx.conf        Exposes metrics (in the docker network) at path `/nginx_status`
└── monitor/
    └── prometheus.yml

Instrument Services to Expose Metrics Data

Prometheus collects metrics data from various sources. These pages describe how to expose metrics from different sources:

Grafana Dashboards for Visualizing Data

Defining a Grafana dashboard from scratch is time-consuming. You can import dashboards by ID from Grafanalabs and connect them to your own data source.

Discover, explore, and download dashboards: https://grafana.com/grafana/dashboards/

Nginx Dashboards for nginx-prometheus-exporter are fairly standard:

Dashboard ID Description
12708 Official Nginx exporter dashboard, designed for the exporter, 2020-07-26
12452 Another dashboard designed explicitly for nginx-prometheus-exporter, 2022-11-21

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