Writing Event-Driven Serverless Code to Build Scalable Applications

Author: Chirag Aggarwal | Published: 2025-01-26 | Generated: 2025-01-26 | Domain: dev.to
Tags: ‘#serverless’ ‘#event-driven’ ‘#appwrite’ ‘#nodejs’ ‘#cloud-architecture’

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TLDR

Serverless means delegating server provisioning, patching, security, and elastic scaling to a cloud provider—not eliminating servers altogether. The article advocates decomposing selected application tasks into independently triggered functions so infrequent work, such as a welcome email, does not consume the same always-on resources as high-traffic paths. It demonstrates this pattern with Appwrite: a users.*.create event invokes a Node.js function that uses Resend to email each newly created user.

Key Takeaways

• Serverless shifts operational responsibility: Cloud providers run the infrastructure while developers focus on application code; self-managed VPS or hardware still requires patching, networking, SSL, security, and scaling work.
• Functions enable independent scaling: Breaking work into small, event-triggered units lets high-frequency features and infrequent background tasks consume resources on separate demand curves, reducing overprovisioning.
• Appwrite provides an integrated backend: Its open-source BaaS combines authentication, databases, storage, and functions, avoiding the need to assemble separate cloud services for a basic event-driven workflow.
• The example uses Node 20 and Appwrite tooling: Initialize a project with appwrite init, create a function via appwrite init function, then deploy it with appwrite push functions.
• User creation triggers email delivery: The function listens for Appwrite’s users.*.create event, reads req.body.email, and calls Resend’s email API. Resend requires an API key and a connected sending domain.

Images & Media

• Cover image for Writing Event-Driven Serverless Code to Build Scalable Applications — Article cover illustration.
• Serverless Deployment Diagram — Illustrates deploying code to a cloud provider that manages infrastructure.
• Functions Diagram — Shows application concerns divided into discrete functions.
• Function Deployment Options — Compares serverless function deployment platforms.
• Functions Architecture — Depicts the user-creation and email-function workflow.
• Appwrite Console showing Events — Appwrite console configuration for attaching the users.*.create event.
• Conclusion Image — Closing serverless illustration.

Referenced Links

• Original article on Chirag Aggarwal’s site — Original publication.
• Appwrite — Open-source backend platform used for authentication and functions.
• Appwrite CLI installation documentation — Setup instructions for the CLI.
• Appwrite platform events documentation — Reference for configuring event-driven function triggers.
• Resend — Email service used by the demonstration function.
• Resend documentation — Setup and sending-domain requirements for Resend.