Starting the Rails server

A generated app does nothing until something runs it

Rails CLI: rails new generated a whole app: models, views, controllers and config, sitting on disk. None of it does anything yet. A Rails app is just files until a process starts reading requests and running the code. That process is bin/rails server.

bin/rails server

Running it in this project prints something like this:

=> Booting Puma
=> Rails 8.1.4 application starting in development
=> Run `bin/rails server --help` for more startup options
Puma starting in single mode...
* Listening on http://127.0.0.1:3000

Three things happened. Rails booted, loading config/application.rb, initializers and the rest. Puma started as the web server underneath. And it began listening on port 3000, the default. Opening http://localhost:3000 in a browser now reaches this process.

Puma was already mentioned, this course goes deeper

The web: request-response named Puma as the first layer a request passes through, the piece that receives raw HTTP and hands it to Rack. That course followed the whole request journey. This one is about Puma: starting it, configuring it, and what "workers" and "threads" in its output and config mean.

Stopping it

Ctrl+C in the terminal running bin/rails server stops Puma and returns you to the shell. There's no separate stop command; the server runs only while that terminal keeps it in the foreground.

Key takeaways

• A generated app is inert until bin/rails server starts Puma, the process that listens for HTTP requests.
• The boot output shows Rails loaded, Puma started, and it's listening, on port 3000 by default.
• The web: request-response covered the whole journey; this course is about Puma itself.
• Ctrl+C stops the server, which runs only while its terminal process lives.