Web Application Monitoring Stack

A comprehensive monitoring stack to observe a sample web application using Prometheus, Grafana, Node Exporter, and Alertmanager.

Architecture

This project spins up the following services using Docker Compose:

• Web Application (web-app): A Node.js Express application instrumentation with prom-client exposing default Node.js metrics, HTTP request metrics, and custom business logic counters (app_user_signups_total, app_user_signup_failures_total).
• Nginx (nginx): Acts as a reverse proxy to the Node.js application, also exposing stub_status for monitoring connection stats.
• Nginx Exporter (nginx-exporter): Connects to Nginx stub_status and exports metrics to Prometheus.
• Prometheus (prometheus): The core time-series database scraping metrics from the Web App, Nginx Exporter, Node Exporter, and itself. Also evaluates alerting rules.
• Node Exporter (node-exporter): Exposes hardware and OS metrics of the host machine. (Runs on port 9101 to avoid common port conflicts).
• Alertmanager (alertmanager): Handles alerts triggered by Prometheus and routes them (configured for Slack incoming webhooks).
• Grafana (grafana): Visualization platform for the scraped metrics. Comes pre-provisioned with data sources and a comprehensive dashboard.

Requirements

• Docker
• Docker Compose

Getting Started

1. Clone the repository:

   git clone <repository_url>
   cd <repository_dir>

2. Configure Alertmanager (Optional but recommended):

   • Edit alertmanager/alertmanager.yml
   • Replace the Slack api_url and channel placeholders with your actual Slack Webhook setup.

3. Start the stack:

   docker compose up -d

4. Access the Services:

   • Sample Web App: http://localhost:80 (via Nginx) or http://localhost:8080 (Direct)
   • Prometheus UI: http://localhost:9091
   • Alertmanager UI: http://localhost:9093
   • Grafana UI: http://localhost:4000
     • Default credentials: admin / admin

Dashboards

A unified dashboard named Web Application Monitoring is provisioned automatically in Grafana, featuring:

• System Health: CPU & Memory usage.
• Application Performance: HTTP Request Latency (P95) and Request Rate by Status Code.
• Business Logic: Total User Signups and Failures.

The picture below shows the dashboard system health:

This dashboard is used to monitor the health and performance of an application or server in real time

Generating Test Data

To generate data for the business logic dashboard panels, send a few POST requests to the sample signup API:

# Generate signup traffic (80% success rate simulated)
curl -X POST http://localhost:8080/api/signup

Then, view the raw metrics:

curl http://localhost:8080/metrics