Add some logging to the diego client

lib/diego/client.rb

@@ -125,12 +125,14 @@ def actual_lrps_by_process_guid(process_guid)
     end
 
     def request_with_error_handling(req)
-      tries ||= 3
+      attempt ||= 1
       http_client.ipaddr = bbs_ip # tell the HTTP client which exact IP to target
+      logger.info("attempt #{attempt}: trying bbs endpoint #{req.path} on #{bbs_ip}")
       http_client.request(req)
     rescue => e
-      ips_remaining.shift
-      retry unless ips_remaining.empty? && (tries -= 1).zero?
+      eliminated_ip = ips_remaining.shift
+      logger.info("attempt #{attempt}: failed to reach bbs server on #{eliminated_ip}, removing from list")
+      retry unless ips_remaining.empty? && (attempt += 1) > 3
       raise RequestError.new(e.message)
     end
 
@@ -144,6 +146,10 @@ def bbs_ip
     attr_reader :http_client, :bbs_url
     attr_accessor :ips_remaining
 
+    def logger
+      @logger ||= Steno.logger('cc.diego.client')
+    end
+
     def protobuf_encode!(hash, protobuf_message_class)
       # See below link to understand proto3 message encoding
       # https://developers.google.com/protocol-buffers/docs/reference/ruby-generated#message

spec/diego/client_spec.rb

@@ -11,13 +11,16 @@ module Diego
     let(:client_key_file) { File.join(Paths::FIXTURES, 'certs/bbs_client.key') }
     let(:bbs_ip_1) { '1.2.3.4' }
     let(:bbs_ip_2) { '5.6.7.8' }
+    let(:logger) { instance_double(Steno::Logger) }
 
     subject(:client) do
       Client.new(url: bbs_uri, ca_cert_file: ca_cert_file, client_cert_file: client_cert_file, client_key_file: client_key_file,
                  connect_timeout: 10, send_timeout: 10, receive_timeout: 10)
     end
     before do
       allow(::Resolv).to receive(:getaddresses).with(bbs_domain).and_return([bbs_ip_1, bbs_ip_2])
+      allow(Steno).to receive(:logger).and_return(logger)
+      allow(logger).to receive(:info)
     end
 
     describe 'configuration' do
@@ -797,6 +800,21 @@ module Diego
           expect(http_client).to have_received(:ipaddr=).with(bbs_ip_2).twice
         end
       end
+
+      context 'logging' do
+        before do
+          stub_request(:post, "https://#{bbs_domain}:#{bbs_port}/fake_path").
+            to_raise(StandardError.new('error message')).then.
+            to_return(status: 200)
+        end
+
+        it 'logs before each request and after each failed request' do
+          client.request_with_error_handling(Net::HTTP::Post.new('/fake_path'))
+          expect(logger).to have_received(:info).with(%r{attempt 1: trying bbs endpoint /fake_path on #{bbs_ip_1}}).once
+          expect(logger).to have_received(:info).with(/attempt 1: failed to reach bbs server on #{bbs_ip_1}, removing from list/).once
+          expect(logger).to have_received(:info).with(%r{attempt 1: trying bbs endpoint /fake_path on #{bbs_ip_2}}).once
+        end
+      end
     end
   end
 end