Add too many requests page

app/controllers/errors_controller.rb

@@ -22,4 +22,11 @@ class ErrorsController < ApplicationController
       format.json { render json: { error: "Unprocessable entity" }, status: :unprocessable_entity }
     end
   end
+
+  def too_many_requests
+    respond_to do |format|
+      format.html { render status: :too_many_requests }
+      format.json { render json: { error: "Too many requests" }, status: :too_many_requests }
+    end
+  end
 end

app/views/errors/too_many_requests.erb

@@ -0,0 +1,8 @@
+<% content_for :title, "Sorry, you have sent too many requests to our service" %>
+
+<div class="govuk-grid-row">
+  <div class="govuk-grid-column-two-thirds">
+    <h1 class="govuk-heading-l"><%= content_for(:title) %></h1>
+    <p class="govuk-body">Try again in a minute.</p>
+  </div>
+</div>

config/routes.rb

@@ -71,6 +71,7 @@ Rails.application.routes.draw do
 
   scope via: :all do
     match "/404", to: "errors#not_found"
+    match "/429", to: "errors#too_many_requests"
     match "/422", to: "errors#unprocessable_entity"
     match "/500", to: "errors#internal_server_error"
   end