Print on Demand

Sam Ruby

Scaling discussions often lead to recommendations to add more memory, more CPU, more machines, more regions, more, more, more. This post is different. It focuses instead on the idea of decomposing parts of your applications into event handlers, sta

Fly.io

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Sam Ruby

•5 min read•beginner•

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HTMLJavaScriptLaravelNGINXRailsRuby

Overview

The article discusses the concept of Print on Demand, focusing on optimizing application resource allocation by using event-driven architectures. It emphasizes the benefits of separating PDF generation from the main application to improve performance and resource management.

What You'll Learn

1

How to implement on-demand PDF generation using Fly.io

2

Why separating PDF generation from your main application improves resource allocation

3

When to use Fly-Replay for integrating PDF generation into existing applications

Prerequisites & Requirements

Basic understanding of web application architecture
Familiarity with Git for cloning repositories

Key Questions Answered

How does the PDF generation process work in the Fly.io environment?

The PDF generation process involves replaying a request to a PDF appliance, which uses a Chrome instance to convert the HTML response into a PDF. This method allows for efficient resource usage by only allocating memory when needed and reusing the Chrome instance across requests.

What are the advantages of using a separate application for PDF generation?

Using a separate application for PDF generation reduces the overall memory footprint and startup time of the main application. It allows for predictable memory usage and the ability to scale the PDF generation service independently from the rest of the application.

What tools are commonly used for PDF generation in web applications?

Common tools for PDF generation include Puppeteer, Grover, Playwright, ChromicPDF, and BrowserShot. These tools typically launch a headless Chrome browser to render web pages and convert them into PDF format.

How can Fly-Replay be integrated into existing applications?

Fly-Replay can be integrated by adding a response header to requests intended for PDF generation. This can be done on specific routes or globally using middleware or a front-end server like NGINX.

Technologies & Tools

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Platform

Fly.io

Used for deploying and managing applications with on-demand resource allocation.

Browser

Chrome

Utilized in a headless mode for rendering web pages to generate PDFs.

Programming Language

Javascript

The code for the PDF appliance is written in JavaScript and runs on Bun.

Key Actionable Insights

1
Consider decomposing your application into smaller services to optimize resource usage.
By identifying and separating resource-intensive processes like PDF generation, you can improve the performance and scalability of your application.

2
Utilize Fly.io's auto_stop_machines setting to manage resource allocation effectively.
This setting allows machines to exit when idle, ensuring that resources are only used when necessary, which can lead to cost savings.

3
Explore the provided GitHub repository for a ready-to-deploy PDF generation solution.
The repository contains production-ready code that can be quickly integrated into your existing applications, saving development time.

Common Pitfalls

1

Failing to separate resource-intensive tasks from the main application can lead to performance bottlenecks.

When all tasks are handled by a single application, it can become overloaded, leading to slower response times and increased resource consumption.

Related Concepts

Event-driven Architecture

Microservices

Resource Optimization Strategies