Log Content-Length bytes in API resposne

This will be useful to measure bandwidth sent in response to an API
request, particularly with measuring the /api/v4/internal/lfs endpoint.

client/client_test.go

@@ -94,6 +94,7 @@ func testSuccessfulGet(t *testing.T, client *GitlabNetClient) {
 		require.Equal(t, logrus.InfoLevel, entries[0].Level)
 		require.Contains(t, entries[0].Message, "method=GET")
 		require.Contains(t, entries[0].Message, "status=200")
+		require.Contains(t, entries[0].Message, "content_length_bytes=")
 		require.Contains(t, entries[0].Message, "Finished HTTP request")
 		require.Contains(t, entries[0].Message, "correlation_id=")
 	})
@@ -120,6 +121,7 @@ func testSuccessfulPost(t *testing.T, client *GitlabNetClient) {
 		require.Equal(t, logrus.InfoLevel, entries[0].Level)
 		require.Contains(t, entries[0].Message, "method=POST")
 		require.Contains(t, entries[0].Message, "status=200")
+		require.Contains(t, entries[0].Message, "content_length_bytes=")
 		require.Contains(t, entries[0].Message, "Finished HTTP request")
 		require.Contains(t, entries[0].Message, "correlation_id=")
 	})

client/gitlabnet.go

@@ -156,6 +156,10 @@ func (c *GitlabNetClient) DoRequest(ctx context.Context, method, path string, da
 		return nil, err
 	}
 
+	if response.ContentLength >= 0 {
+		logger = logger.WithField("content_length_bytes", response.ContentLength)
+	}
+
 	logger.Info("Finished HTTP request")
 
 	return response, nil