Add configurable timeout value

lib/prerender_rails.rb

@@ -111,12 +111,19 @@ def call(env)
           return cached_response.finish
         end
 
-        prerendered_response = get_prerendered_page_response(env)
-
-        if prerendered_response
-          response = build_rack_response_from_prerender(prerendered_response)
-          after_render(env, prerendered_response)
-          return response.finish
+        begin
+          prerendered_response = get_prerendered_page_response(env)
+
+          if prerendered_response
+            response = build_rack_response_from_prerender(prerendered_response)
+            after_render(env, prerendered_response)
+            return response.finish
+          end
+        rescue Timeout::Error
+          if @options[:read_timeout]
+            response = Rack::Response.new(nil, 503, nil)
+            return response.finish
+          end
         end
       end
 
@@ -183,6 +190,7 @@ def get_prerendered_page_response(env)
         req.basic_auth(ENV['PRERENDER_USERNAME'], ENV['PRERENDER_PASSWORD']) if @options[:basic_auth]
         http = Net::HTTP.new(url.host, url.port)
         http.use_ssl = true if url.scheme == 'https'
+        http.read_timeout = @options[:read_timeout] if @options[:read_timeout]
         response = http.request(req)
         if response['Content-Encoding'] == 'gzip'
           response.body = ActiveSupport::Gzip.decompress(response.body)

test/lib/prerender_rails.rb

@@ -102,6 +102,20 @@
   end
 
 
+  it 'should return a timeout error to the crawler if the request takes longer than the read_timeout argument' do
+    request = Rack::MockRequest.env_for '/', 'HTTP_USER_AGENT' => bot
+    stub_request(:get, @prerender.build_api_url(request))
+      .with(headers: { 'User-Agent': bot })
+      .to_raise(Timeout::Error)
+
+    err = assert_raises Timeout::Error do
+      Rack::Prerender.new(@app, read_timeout: 22).call(request)
+    end
+
+    assert_equal err.message, '503 Service Unavailable'
+  end
+
+
   it "should continue to app routes if the url is part of the regex specific blacklist" do
     request = Rack::MockRequest.env_for "/search/things/123/page", "HTTP_USER_AGENT" => bot
     response = Rack::Prerender.new(@app, blacklist: ['^/search', '/help']).call(request)