proc.rb

# somewhere in your middleware stack...
# request.env['yourapp.someid'] = "1337"

YourApp::Application.configure do
  config.log_tags = [
    -> request {
      request.env['yourapp.someid']
    }
  ]
end

# [1337] Processing by ProjectsController#index as HTML

string.rb

YourApp::Application.configure do
  config.log_tags = ["Static"]
end

# [Static] Processing by ProjectsController#index as HTML

symbol.rb

YourApp::Application.configure do
  config.log_tags = [:uuid]
end

# [71ba53fd717c67a6677a058f4a5acdf4] Processing by ProjectsController#index as HTML