Rails Trace

What code runs when you request a page from a Ruby on Rails application?

Here is an annotated trace showing every method call within Rails and its dependencies. It is for an example application that loads a blog post from the database and renders a page containing the post's title.

Scroll to see the trace


ActionDispatch::Routing::RouteSet is the last Rack middleware to be called. It looks up what route the request refers to using ActionDispatch::Journey::Router. Later this route will be used to call the right controller in our application.

When a Rails application starts the routes defined in config/routes.rb are processed to make it easier to lookup which route a request should use.

Created by Chris Zetter in a tribute to Rails and its many contributors.

Read out more about how the trace was made.

You can see the code that powers this page and suggest resources to link to on GitHub.