Monitor Containers with Prometheus & Grafana

Learning objectives

• Deploy the monitoring services
• Collect host + container metrics
• Import a Grafana dashboard
• Configure an alert rule
• Validate the alert fires under load

Before you start

Required software: Docker Engine 24+ with Compose v2

Prerequisites: Docker Monitoring & Troubleshooting path

1. Download and unzip the lab.
2. Start the stack: docker compose up -d.
3. Open Grafana at the URL in the README (default creds in README).

Instructions

Hints

💡 Prometheus shows no container metrics

cAdvisor exposes container metrics on its own port — Prometheus must have a scrape job targeting it. Check prometheus.yml scrape_configs for a cadvisor target.

💡 How do I make the alert fire?

The lab includes a load generator. Set the alert threshold below the load it produces, then run it and watch the alert transition to firing.

Validate your work

From the lab folder, run:

bash validation/validate.sh

The script reads only your local Docker state, never transmits data off your machine, and returns a status code:

• 0 — Lab successfully completed
• 1 — Validation failed
• 2 — Required dependency missing
• 3 — Lab environment not running
• 4 — Configuration error
• 5 — Validation timed out

Note: validation targets Linux first. On Docker Desktop (macOS/Windows) some host-level checks (e.g. disk usage) may report differently; each script documents its limitations.

Solution

Reset the lab

• docker compose down -v && docker compose up -d from the original lab files restores the starting (broken) state.

Interview questions

• What do cAdvisor and node-exporter each provide?
• How does Prometheus discover what to scrape?
• What is the difference between a pending and firing alert?