Only capture first line of stacktrace for unexpected RequestAttempt exceptions (#1736)

Author: gavinbunney

zuul-core/src/main/java/com/netflix/zuul/niws/RequestAttempt.java

@@ -19,7 +19,6 @@
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.node.ObjectNode;
-import com.google.common.base.Throwables;
 import com.netflix.appinfo.AmazonInfo;
 import com.netflix.appinfo.InstanceInfo;
 import com.netflix.client.config.IClientConfig;
@@ -340,7 +339,13 @@ public void setException(Throwable t) {
             } else {
                 error = t.getMessage();
                 exceptionType = t.getClass().getSimpleName();
-                cause = Throwables.getStackTraceAsString(t);
+
+                // for unexpected exceptions, just capture the first line of the stacktrace
+                // otherwise we risk large stacktraces in memory and metrics systems
+                StackTraceElement[] stackTraceElements = t.getStackTrace();
+                if (stackTraceElements.length > 0) {
+                    cause = stackTraceElements[0].toString();
+                }
             }
         }
     }

zuul-core/src/test/java/com/netflix/zuul/niws/RequestAttemptTest.java

@@ -18,6 +18,9 @@
 
 import com.netflix.zuul.exception.OutboundErrorType;
 import com.netflix.zuul.netty.connectionpool.OriginConnectException;
+import io.netty.handler.codec.http2.DefaultHttp2Connection;
+import io.netty.handler.codec.http2.Http2Error;
+import io.netty.handler.codec.http2.Http2Exception;
 import org.junit.jupiter.api.Test;
 
 import javax.net.ssl.SSLHandshakeException;
@@ -26,6 +29,7 @@
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.when;
 
 public class RequestAttemptTest {
@@ -77,4 +81,38 @@ void originConnectExceptionWithCauseNotUnwrapped() {
         assertEquals("ORIGIN_CONNECT_ERROR", attempt.getError());
         assertEquals("java.lang.RuntimeException: socket failure", attempt.getCause());
     }
+
+    @Test
+    void h2ExceptionCauseHandled() {
+        // mock out a real-ish h2 stream exception
+        Exception h2Exception = spy(Http2Exception.streamError(
+                100,
+                Http2Error.REFUSED_STREAM,
+                "Cannot create stream 100 greater than Last-Stream-ID 99 from GOAWAY.",
+                new Object[] {100, 99}));
+
+        // mock a stacktrace to ensure we don't actually capture it completely
+        when(h2Exception.getStackTrace()).thenReturn(new StackTraceElement[] {
+            new StackTraceElement(
+                    DefaultHttp2Connection.class.getCanonicalName(),
+                    "createStream",
+                    "DefaultHttp2Connection.java",
+                    772),
+            new StackTraceElement(
+                    DefaultHttp2Connection.class.getCanonicalName(),
+                    "checkNewStreamAllowed",
+                    "DefaultHttp2Connection.java",
+                    902)
+        });
+
+        RequestAttempt attempt = new RequestAttempt(1, null, null, "target", "chosen", 200, null, null, 0, 0, 0);
+        attempt.setException(h2Exception);
+
+        assertEquals("Cannot create stream 100 greater than Last-Stream-ID 99 from GOAWAY.", attempt.getError());
+        assertEquals("StreamException", attempt.getExceptionType());
+
+        assertEquals(
+                "io.netty.handler.codec.http2.DefaultHttp2Connection.createStream(DefaultHttp2Connection.java:772)",
+                attempt.getCause());
+    }
 }