Stop Fearing DevOps: A Rails Developer's Guide to Docker

I know that DevOps and server management can be very confusing, even if you have years of experience writing Ruby code. For a long time, deploying a Rails app meant SSHing into a server, installing Ruby, installing Postgres, configuring Nginx, and praying you didn't break anything. Then Docker came along and changed everything. But if you read the official Docker documentation, it uses a lot of fancy academic language that makes it sound much harder than it actually is. In this article, I will explain exactly how Docker works, from beginner concepts to advanced usage with Kamal 2 in Rails 8. LEVEL 1: What actually is Docker? (The Basics) Imagine you build a wooden chair in your garage. You have all your specific tools, your specific brand of glue, and your specific temperature. The chair comes out perfectly. Then, you send the blueprints to your friend in another country. They try to build it, but their garage is too humid, their glue is different, and the chair collapses. This is the