Generate user agent header for GCP Client

lib/google_api/cloud_platform/client.rb

@@ -82,6 +82,10 @@ module GoogleApi
       def token_life_time(expires_at)
         DateTime.strptime(expires_at, '%s').to_time.utc - Time.now.utc
       end
+
+      def user_agent_header
+        { 'User-Agent': "GitLab/#{Gitlab::VERSION.match('(\d+\.\d+)').captures.first} (GPN:GitLab;)" }
+      end
     end
   end
 end

spec/lib/google_api/cloud_platform/client_spec.rb

@@ -125,4 +125,13 @@ describe GoogleApi::CloudPlatform::Client do
       it { is_expected.to be_nil }
     end
   end
+
+  describe '#user_agent_header' do
+    subject { client.instance_eval { user_agent_header } }
+
+    it 'returns the correct major and minor GitLab version ' do
+      stub_const('Gitlab::VERSION', '10.3.0-pre')
+      expect(subject).to eq({ 'User-Agent': 'GitLab/10.3 (GPN:GitLab;)' })
+    end
+  end
 end