Newsletter Service

A production-oriented Rust backend service for managing newsletter subscriptions and email delivery, built with async execution, explicit failure handling, and observability in mind.

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Table of Contents

1. Overview
2. Features
3. Architecture & Design Decisions
4. Getting Started
5. Operational Considerations
6. Acknowledgements

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Overview

This project implements a production-grade newsletter backend in Rust. It is designed to handle:

• Subscription management
• Confirmation workflows
• Async email delivery
• Observability and logging
• Fault-tolerant, predictable behavior under load

This project prioritizes correctness, explicit failure handling, and predictable performance over rapid iteration.

It is intended to demonstrate how to build robust, production-ready systems in Rust, suitable for real-world workloads.

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Features

• Async HTTP APIs for subscription management
• Persistent storage via PostgreSQL
• Background tasks for email delivery
• Structured logging and observability hooks
• Integration and unit tests for critical workflows
• Idempotent operations to prevent duplicate emails

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Architecture & Design Decisions

• Async-first design: All IO operations use tokio async runtime for scalability.
• Application state container: Shared resources (DB pool, configuration) wrapped in Arc for safe concurrent access.
• Error handling strategy: Explicit Result types; errors are logged and surfaced to observability system.
• Background email delivery: Tasks are scheduled asynchronously, with retry logic for failed sends.
• Idempotency: Subscription endpoints ensure duplicate requests do not result in multiple emails.
• Test strategy: Unit tests for core logic; integration tests for DB and email delivery flows.
• Extensions beyond reference architecture: Added idempotency, retry logic, and observability hooks to simulate real production requirements.

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Getting Started

Prerequisites

• Rust 1.72+
• PostgreSQL
• Cargo & rustfmt / clippy for linting
• .env file for configuration (DB URL, email credentials)

Installation

git clone https://github.com/yourusername/newsletter-service.git
cd newsletter-service
cargo build

## Acknowledgements
Initial architecture and learning reference inspired by *Zero to Production in Rust* by Luca Palmieri.  
All design decisions, implementations, and enhancements beyond the reference were made independently to reinforce understanding and simulate production constraints.