Running code when the Ruby on Rails webserver boots

Several approaches exist for running code exclusively when a Rails webserver boots, rather than during rake tasks, console sessions, or other Rails commands. Options include: using the Railtie server do block (Rails 6.1+, requires Rails.application.load_server in config.ru), placing code directly in config.ru, writing a Puma plugin for deeper lifecycle hooks, inspecting the call stack for webserver fingerprints (brittle but broadly compatible), or using Rack middleware to trigger code on the first request. The best choice depends on context — gems/engines should prioritize broad compatibility, while application-specific code should avoid leaving hidden footguns.

Source: https://island94.org/2026/07/running-code-when-the-ruby-on-rails-webserver-boots. 8sync News only summarizes and links out; content copyright belongs to the authors and original sources.