dnsdist: Use different ports for custom OT responders

Signed-off-by: Remi Gacogne <remi.gacogne@powerdns.com>

Author: rgacogne

regression-tests.dnsdist/test_OpenTelemetryTracing.py

@@ -14,6 +14,7 @@
 import google.protobuf.json_format
 import opentelemetry.proto.trace.v1.trace_pb2
 
+from dnsdisttests import pickAvailablePort
 import test_Protobuf
 
 
@@ -715,6 +716,11 @@ def servfailOnTraceParent(request: dns.message.Message):
 
 
 class TestOpenTelemetryTracingStripIncomingTraceParent(DNSDistOpenTelemetryProtobufTest):
+    # this test suite uses a different responder port
+    # because it uses a different responder logic so we
+    # need to make sure we are not hitting the backend
+    # from a different test
+    _testServerPort = pickAvailablePort()
     _yaml_config_params = [
         "_testServerPort",
     ]
@@ -817,6 +823,11 @@ def verifyTraceparentInQuery(request: dns.message.Message):
 
 
 class TestOpenTelemetryTracingSendTraceparentDownstream(DNSDistOpenTelemetryProtobufTest):
+    # this test suite uses a different responder port
+    # because it uses a different responder logic so we
+    # need to make sure we are not hitting the backend
+    # from a different test
+    _testServerPort = pickAvailablePort()
     _yaml_config_params = [
         "_testServerPort",
     ]