🟢 Pulsemon

A production-grade, multi-tenant backend system built in Go that continuously probes HTTP/HTTPS endpoints, tracks latency histograms, monitors SLA compliance, inspects SSL certificates, and delivers email alerts when things go wrong.

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What It Does

Pulsemon watches your HTTP/HTTPS services so you don't have to. Register an endpoint, choose a probe interval, and the system takes care of the rest — probing on schedule, recording results, detecting failures, and alerting you before your users notice something is wrong.

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Features

• HTTP & HTTPS Probing — Continuously probes registered endpoints on a configurable schedule
• Latency Tracking — Records avg, p95, and p99 latency per service
• Failure Streak Detection — Alerts when a service fails 3 or more consecutive times
• SLA Compliance Monitoring — Tracks uptime percentage against your configured SLA target
• SSL Certificate Inspection — Monitors certificate validity and expiry for HTTPS endpoints
• Email Alerts via Resend — Notifies you on failure streaks, SLA breaches, SSL expiry, and recovery
• Alert Cooldown — Prevents alert spam with a 30-minute cooldown window per service
• Multi-Tenant — Each user owns and sees only their own data
• Service Quota — Each user can monitor up to 3 active services (slot-based)
• 30-Day Data Retention — Probe results automatically purged after 30 days
• REST API — Clean, documented API for integration with any frontend

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Tech Stack

Concern	Technology
Language	Go
HTTP Framework	Gin
Database	PostgreSQL
ORM & Migrations	GORM
Authentication	JWT
Email	Resend API
SSL Inspection	Go crypto/tls
Configuration	Environment Variables

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Project Structure

pulsemon/
│
├── cmd/
│   └── api/
│       └── main.go               # Entry point — wires everything together
│
├── internal/
│   ├── auth/                     # Registration, login, JWT issuance
│   │   ├── handler.go
│   │   ├── service.go
│   │   └── repository.go
│   │
│   ├── services/                 # Service CRUD + 3-service quota enforcement
│   │   ├── handler.go
│   │   ├── service.go
│   │   └── repository.go
│   │
│   ├── scheduler/                # Ticker goroutines per service
│   │   └── scheduler.go
│   │
│   ├── worker/                   # HTTP probe + SSL inspection worker pool
│   │   ├── pool.go
│   │   └── probe.go
│   │
│   ├── processor/                # Stores results, updates streaks, calculates SLA
│   │   └── processor.go
│   │
│   ├── alerts/                   # Email alert engine with cooldown logic
│   │   └── engine.go
│   │
│   └── dashboard/                # Read-only health data endpoints
│       ├── handler.go
│       └── repository.go
│
├── pkg/
│   ├── database/                 # PostgreSQL connection via GORM
│   │   └── postgres.go
│   │
│   ├── middleware/               # JWT auth middleware for Gin
│   │   └── auth.go
│   │
│   ├── models/                   # Shared domain models (User, Service, etc.)
│   │   └── models.go
│   │
│   └── config/                   # Environment variable loading
│       └── config.go
│
├── .env.example                  # Environment variable template
├── go.mod
└── go.sum

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Getting Started

Prerequisites

• Go 1.21+
• PostgreSQL 14+
• A Resend account and API key

Installation

1. Clone the repository

git clone https://github.com/hayordeji/pulsemon.git

2. Install dependencies

go mod tidy

3. Set up environment variables

cp .env.example .env

Open .env and fill in your values (see Environment Variables section below).

4. Create the PostgreSQL database

createdb pulsemon

5. Run the application

go run cmd/api/main.go

The server starts on http://localhost:8080 by default.

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Environment Variables

# Server
APP_PORT=8080
APP_ENV=development

# Database
DB_HOST=localhost
DB_PORT=5432
DB_USER=postgres
DB_PASSWORD=yourpassword
DB_NAME=service_monitor

# JWT
JWT_SECRET=your_jwt_secret_key
JWT_EXPIRY_HOURS=24

# Resend Email
RESEND_API_KEY=re_your_api_key
RESEND_FROM_EMAIL=alerts@yourdomain.com

# Worker Pool
WORKER_POOL_SIZE=20

# Alert Cooldown (minutes)
ALERT_COOLDOWN_MINUTES=30

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API Reference

All protected routes require:

Authorization: Bearer <jwt_token>

Auth

Method	Route	Description	Auth
POST	/auth/register	Create a new account	No
POST	/auth/login	Login and receive JWT	No

Services

Method	Route	Description	Auth
GET	/services	List all services (summary)	Yes
POST	/services	Register a new service	Yes
GET	/services/:id	Get full service details	Yes
PUT	/services/:id	Update service configuration	Yes
DELETE	/services/:id	Delete a service permanently	Yes

Dashboard

Method	Route	Description	Auth
GET	/dashboard/:service_id	Health overview for a service	Yes
GET	/dashboard/:service_id/alerts	Alert history for a service	Yes

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Business Rules

• A user may have at most 3 active services at any time
• Deleting a service frees the slot — it is slot-based, not lifetime-limited
• Service URLs are immutable after creation — delete and recreate to change a URL
• Probe results are retained for 30 days then automatically purged
• Failure streak alert triggers at 3 or more consecutive failures
• SLA breach alert triggers when sla_percentage drops below sla_target
• SSL expiry alert triggers when certificate has fewer than 30 days remaining
• Alert cooldown is 30 minutes — no repeated alerts within that window
• All service routes return 404 for both missing and unauthorized resources — other users' data is never revealed

Alert Types

Alert	Trigger Condition
failure_streak	3 or more consecutive probe failures
sla_breach	SLA percentage drops below configured target
ssl_expiry	SSL certificate expires in fewer than 30 days
recovery	Service recovers after a failure streak

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Author

Built by Ayodeji Shoga (https://github.com/hayordeji) as a side project.