In addition to the Solid gems, another important update in Rails 8 is the handcrafted Dockerfile designed specifically for production deployments.

Understanding the Rails 8 Production Dockerfile

This Dockerfile is optimized for production, not development. If you want to use containerized development environments, Rails offers extensive support for Dev Containers, which you can explore through the link provided.

There's a lot happening in this Dockerfile, but I want to highlight a few key details:

Multi-Stage Build for a Smaller Image Size

• This approach minimizes the final Docker image, ensuring efficient performance and faster deployments.
• You can see the final stage implementation, which sets up the app image efficiently.

Optimized Entry Point & HTTP/2 Support

• At the end of the Dockerfile, we have an entry point script that ensures the database is properly prepared before launching the Rails server.
• The server runs with the bin/thrust command, using a new dependency called Thruster.
• Thruster optimizes Rails for serving static assets, handling HTTP/2 requests, and improving overall performance.

Why This Matters for Non-Docker Deployments

If you don’t use this Dockerfile for deployment—such as when deploying to Hatchbox or other platforms—you need to replicate these optimizations manually. Ensuring that:

1. Static assets are efficiently served.
2. Database migrations run automatically.
3. HTTP/2 support is enabled for better performance.

Rails 8 Deployment: Kamal vs. Hatchbox

This Dockerfile is designed to work with Kamal, the new built-in Rails deployment tool.

• Kamal automates Rails deployments and is deeply integrated into Rails 8.
• If you want to learn more about Kamal, there are blogs, books, and guides linked below.

Personally, I don’t use Kamal because:

• It’s still new, and I prefer something more battle-tested.
• I want a simple deployment process that just works.
• I don’t want to learn extra tooling—I want to focus on building the app.

Instead, I prefer using Hatchbox, a straightforward deployment service that makes it easy to ship Rails apps to production without extra complexity.

That being said, Kamal is worth exploring, and I may revisit it in the future. If you’re looking for a fast, reliable way to deploy Rails 8 apps, Hatchbox remains my go-to solution.

Now that we’ve covered Docker, Kamal, and deployment considerations, it’s time to dive into building our Rails 8 application.