API Gateway Monitor

Infrastructure reliability demo · NestJS · PostgreSQL · Docker
Built by Altura Codeworks as a backend showcase.

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🧭 Overview

A minimal backend service that simulates API uptime monitoring — the kind of tool you’d run beside gateways and microservices in production.

It registers APIs, performs scheduled health checks, logs their response times, and produces an uptime summary report — all documented via Swagger UI.

Designed as a backend / DevOps engineering demo, it focuses on system reliability patterns rather than UI features.

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⚙️ Tech Stack

Layer	Technology	Purpose
Framework	NestJS 10+	Structured, modular Node.js backend
Database	PostgreSQL 16 + TypeORM	Entities, repositories, logging
Scheduling	@nestjs/schedule (cron)	Background health checks
HTTP client	Axios via @nestjs/axios	Fast HEAD probes
Documentation	Swagger / OpenAPI	REST interface with linked hints
Containerization	Docker + docker-compose	Single-command spin-up

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🧱 Architecture

src/
├─ config/ → env + TypeORM config
├─ services/ → service registry (CRUD)
│ ├─ service.entity.ts
│ ├─ services.service.ts
│ └─ services.controller.ts
├─ monitoring/ → health checks, logs, uptime summary
│ ├─ log.entity.ts
│ ├─ monitoring.service.ts
│ └─ monitoring.controller.ts
└─ app.module.ts

**Core entities**

| Table | Fields (main) |
|-------|----------------|
| `services` | id · name · baseUrl · isActive · lastCheckedAt · lastStatus |
| `check_logs` | id · serviceId · checkedAt · responseTimeMs · status · errorMessage |

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🧮 Features

✅ Register APIs to monitor
✅ Manual and automated pings (@Cron(EVERY_MINUTE))
✅ Store historical response logs
✅ Aggregate uptime % for last 24h
✅ Configurable per-service check interval
✅ Dockerized Postgres environment + seed data
✅ Swagger UI with discoverable documentation

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🐳 Quick Start (Docker)

1️⃣ Create .env

PORT=3000
DB_HOST=db
DB_PORT=5432
DB_USER=postgres
DB_PASS=postgres
DB_NAME=api_monitor

2️⃣ Launch docker compose up --build

API → http://localhost:3000

Swagger UI → http://localhost:3000/docs

3️⃣ Seed demo data psql -h localhost -U postgres -d api_monitor -f seed.sql

You’ll immediately see populated uptime stats under /monitoring/summary.

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🖼️ Swagger UI Preview

The /monitoring/summary endpoint lists uptime, latency, and health status for each monitored API.

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🔍 Key Endpoints

Method	Path	Description
GET	/services	List registered APIs 🛈 See /monitoring/summary for uptime overview
POST	/services	Register a new service
POST	/monitoring/ping/:id	Manually trigger a health check
GET	/monitoring/summary	Aggregated uptime & latency stats (last 24 h)

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🧾 Example Summary Output

[
  {
    "serviceId": 1,
    "name": "Billing API",
    "baseUrl": "https://api.stripe.com/v1/charges",
    "lastStatus": "OK",
    "lastResponseTimeMs": 152,
    "lastCheckedAt": "2025-11-10T10:30:00Z",
    "checksLast24h": 3,
    "uptimePercentLast24h": 100.0
  },
  {
    "serviceId": 2,
    "name": "CRM Backend",
    "baseUrl": "https://crm.alturacodeworks.com/api/health",
    "lastStatus": "DOWN",
    "lastResponseTimeMs": 982,
    "lastCheckedAt": "2025-11-10T10:27:00Z",
    "checksLast24h": 3,
    "uptimePercentLast24h": 33.3
  }
]

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🖼️ Monitoring Summary Example

🧠 Implementation Highlights

Ping logic — performs HEAD requests with 5-second timeout

Health heuristic — treats status < 500 (except 404) as reachable

Interval logic — honors each service’s checkIntervalMinutes

Fault tolerance — per-service try/catch to avoid cron cascade failures

Aggregation — simple in-memory uptime calculation for demo clarity

🧭 Future Ideas

JWT authentication for restricted endpoints

Configurable schedulers (RabbitMQ / BullMQ)

WebSocket push of latest health status

Lightweight Angular/React dashboard consuming /monitoring/summary

Export to Prometheus / Grafana integration

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🪶 Credits

Built by Yuriy Mykhalchuk · Founder of Altura Codeworks

A demonstration of calm architecture, reliable systems, and measurable uptime.

© 2025 Altura Codeworks · github.com/ymykhal · Upwork Agency