Optimization:Throttle Tag Index Endpoints (#12520)

config/initializers/rack/attack.rb

@@ -30,8 +30,8 @@ module Rack
       track_and_return_ip(request.env["HTTP_FASTLY_CLIENT_IP"])
     end
 
-    throttle("message_throttle", limit: 2, period: 1) do |request|
-      if request.path.starts_with?("/messages") && request.post?
+    throttle("message_tag_throttle", limit: 2, period: 1) do |request|
+      if message_or_tag_request(request)
         track_and_return_ip(request.env["HTTP_FASTLY_CLIENT_IP"])
       end
     end
@@ -42,5 +42,10 @@ module Rack
       Honeycomb.add_field("fastly_client_ip", ip_address)
       ip_address.to_s
     end
+
+    def self.message_or_tag_request(request)
+      (request.path.starts_with?("/messages") && request.post?) ||
+        request.path.include?("/t/")
+    end
   end
 end

spec/initializers/rack/attack_spec.rb

@@ -95,7 +95,7 @@ describe Rack::Attack, type: :request, throttle: true do
     end
   end
 
-  describe "message_throttle" do
+  describe "message_tag_throttle" do
     let(:user) { create(:user) }
     let(:chat_channel) { create(:chat_channel) }
     let(:new_message) do
@@ -106,6 +106,8 @@ describe Rack::Attack, type: :request, throttle: true do
         chat_channel_id: chat_channel.id
       }
     end
+    let(:headers) { { "HTTP_FASTLY_CLIENT_IP" => "5.6.7.8" } }
+    let(:dif_headers) { { "HTTP_FASTLY_CLIENT_IP" => "1.1.1.1" } }
 
     before do
       allow(Pusher).to receive(:trigger).and_return(true)
@@ -113,22 +115,46 @@ describe Rack::Attack, type: :request, throttle: true do
     end
 
     it "throttles creating messages" do
-      headers = { "HTTP_FASTLY_CLIENT_IP" => "5.6.7.8" }
-      dif_headers = { "HTTP_FASTLY_CLIENT_IP" => "1.1.1.1" }
-
       Timecop.freeze do
         valid_responses = Array.new(2).map do
           post messages_path, params: { message: new_message }, headers: headers
         end
         throttled_response = post messages_path, params: { message: new_message }, headers: headers
-        new_api_response = post messages_path, params: { message: new_message }, headers: dif_headers
+        new_response = post messages_path, params: { message: new_message }, headers: dif_headers
 
         valid_responses.each { |r| expect(r).not_to eq(429) }
         expect(throttled_response).to eq(429)
-        expect(new_api_response).not_to eq(429)
+        expect(new_response).not_to eq(429)
         expect(Honeycomb).to have_received(:add_field).with("fastly_client_ip", "5.6.7.8").exactly(6).times
         expect(Honeycomb).to have_received(:add_field).with("fastly_client_ip", "1.1.1.1").exactly(2).times
       end
     end
+
+    # rubocop:disable RSpec/AnyInstance, RSpec/ExampleLength
+    it "throttles viewing tags" do
+      allow_any_instance_of(StoriesController).to receive(:cached_tagged_count).and_return(0)
+      allow_any_instance_of(StoriesController).to receive(:stories_by_timeframe).and_return(Article.none)
+      allow_any_instance_of(Articles::Feeds::LargeForemExperimental).to receive(
+        :published_articles_by_tag,
+      ).and_return(Article.none)
+      tag_path = "/t/#{create(:tag).name}"
+
+      get tag_path, headers: headers # warm up the slow endpoint
+
+      Timecop.freeze do
+        valid_responses = Array.new(2).map do
+          get tag_path, headers: headers
+        end
+        throttled_response = get tag_path, headers: headers
+        new_response = get tag_path, headers: dif_headers
+
+        expect(valid_responses.first).not_to eq(429)
+        expect(throttled_response).to eq(429)
+        expect(new_response).not_to eq(429)
+        expect(Honeycomb).to have_received(:add_field).with("fastly_client_ip", "5.6.7.8").exactly(8).times
+        expect(Honeycomb).to have_received(:add_field).with("fastly_client_ip", "1.1.1.1").exactly(2).times
+      end
+    end
+    # rubocop:enable RSpec/AnyInstance, RSpec/ExampleLength
   end
 end