Solving Docker Compatibility Issues with Kamal -- Planet Argon Blog

Modern deployment tools like Kamal promise simplicity, speed, and power—but what happens when you’re working with a legacy Ruby app that predates many of those tools? We recently helped a client deploy a Ruby 2.2.2 application using Kamal—Basecamp’s container-based deployment solution—and what seemed like a routine task turned into a deep dive into Docker history, deprecation policies, and compatibility cliffs. This post walks through what happened, why it happened, and how we solved it. The Challenge: Ruby 2.2.2 Meets Modern Containers Our client’s app runs on Ruby 2.2.2, which reached end-of-life in 2018. While it might sound ancient in tech years, it’s not uncommon—many businesses still rely on stable legacy apps that haven’t been fully modernized. The challenge wasn't just about deploying an old application—it was about doing so in a modern, containerized environment.