SentinelSwitch

SentinelSwitch is a distributed, event-driven payment transaction and fraud monitoring platform built using Go.
It simulates a real-world payment switch architecture using Kafka, gRPC, PostgreSQL, Redis, Prometheus, Grafana, Docker, and Kubernetes.

This project demonstrates scalable microservice architecture, real-time fraud scoring, async processing, and production-grade observability.

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🧠 Architecture Overview

graph TD
A[API Gateway] --> B[Kafka Transaction Topic]
B --> C[Fraud Engine]
B --> D[Persistence Service]
C --> E[gRPC Risk Scoring]
D --> F[PostgreSQL]
C --> G[Kafka Fraud Result Topic]

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All services expose Prometheus metrics → scraped by Prometheus → visualized in Grafana

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🧩 Tech Stack

Component	Technology Used
Language	Go (Golang)
API Framework	Fiber
Messaging	Apache Kafka
RPC	gRPC
Database	PostgreSQL
Cache	Redis
Metrics	Prometheus
Visualization	Grafana
Containerization	Docker
Orchestration	Kubernetes

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Microservices

1️⃣ API Gateway

• Accepts transaction requests
• Publishes to Kafka
• Returns immediate acknowledgement
• Exposes Prometheus metrics

2️⃣ Fraud Engine Service

• Consumes transactions from Kafka
• Performs rule-based + velocity fraud checks
• Calls Risk Scoring service via gRPC
• Publishes fraud result to Kafka

3️⃣ Risk Scoring Service

• gRPC-based microservice
• Calculates risk score (100–1000)
• Simulates ML model scoring

4️⃣ Persistence Service

• Consumes transaction + fraud results
• Stores into PostgreSQL
• Maintains partitioned transaction tables

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📊 Observability

Each service exports:

• transactions_total
• fraud_detected_total
• grpc_request_duration_seconds
• kafka_consumer_lag
• db_write_latency_seconds
• api_request_count

Prometheus scrapes metrics. Grafana dashboards visualize:

• TPS (Transactions per second)
• Fraud detection ratio
• gRPC latency
• Consumer lag
• DB latency

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🐳 Running with Docker Compose

1️⃣ Clone the repository

git clone https://github.com/gobi722/sentinelswitch.git
cd sentinelswitch