Fix missing transport attribute when flushing telemetry (#902)

* Fix transport attribute not being set

* Update CHANGELOG.md

* Set transport to udp for consistency

Author: rayz

CHANGELOG.md

@@ -1,5 +1,8 @@
 # Changelog
 
+## Unreleased
+* [Fixed] Fix missing transport attribute when flushing telemetry.
+
 ## v0.52.0 / 2025-07-08
 
 * [Added] Add Cardinality common field. See [#883](https://github.com/DataDog/datadogpy/pull/883)

datadog/dogstatsd/base.py

@@ -534,6 +534,7 @@ def socket(self, new_socket):
             except AttributeError:  # _socket can't have a type if it doesn't have sockopts
                 log.info("Unexpected socket provided with no support for getsockopt")
         self._socket_kind = None
+        self._transport = "udp"
         # When the socket is None, we use the UDP optimal payload length
         self._max_payload_size = UDP_OPTIMAL_PAYLOAD_LENGTH
 

tests/unit/dogstatsd/test_statsd.py

@@ -2192,3 +2192,21 @@ def send(self, _):
         statsd.increment("test", 1)
 
         assert statsd.socket is not None
+
+    def test_transport_attribute_present_on_connection_error(self):
+        """
+        Ensure `_transport` attribute is present for telemetry even if the socket is None.
+        """
+        # This test will fail with an AttributeError before the fix.
+        # Use a non-resolvable host to trigger a connection error.
+        statsd = DogStatsd(
+            host='non.existent.host.datadog.internal',
+            telemetry_min_flush_interval=0  # Flush telemetry immediately
+        )
+
+        # This call will attempt to send a metric, fail to create a socket,
+        # and then attempt to send telemetry, which requires `_transport`.
+        statsd.gauge('test.metric', 1)
+
+        assert statsd.socket is None
+        assert statsd._transport is not None