AMLII-2166 - Add UDS Streams support to the DogStatsD client

Includes full support for the unix://, unixstream://, and unixgram:// socket_path prefixes
utilized by DD_DOGSTATSD_URL in preparation to support that feature.

Autodetects SOCK_DGRAM vs SOCK_STREAM for users currently providing a raw socket path.

datadog/dogstatsd/base.py

@@ -49,6 +49,11 @@
 DEFAULT_HOST = "localhost"
 DEFAULT_PORT = 8125
 
+# Socket prefixes
+UNIX_ADDRESS_SCHEME = "unix://"
+UNIX_ADDRESS_DATAGRAM_SCHEME = "unixgram://"
+UNIX_ADDRESS_STREAM_SCHEME = "unixstream://"
+
 # Buffering-related values (in seconds)
 DEFAULT_FLUSH_INTERVAL = 0.3
 MIN_FLUSH_INTERVAL = 0.0001
@@ -731,11 +736,40 @@ def _ensure_min_send_buffer_size(cls, sock, min_size=MIN_SEND_BUFFER_SIZE):
 
     @classmethod
     def _get_uds_socket(cls, socket_path, timeout):
-        sock = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
-        sock.settimeout(timeout)
-        cls._ensure_min_send_buffer_size(sock)
-        sock.connect(socket_path)
-        return sock
+        valid_socket_kinds = [socket.SOCK_DGRAM, socket.SOCK_STREAM]
+        if socket_path.startswith(UNIX_ADDRESS_DATAGRAM_SCHEME):
+            valid_socket_kinds = [socket.SOCK_DGRAM]
+            socket_path = socket_path[len(UNIX_ADDRESS_DATAGRAM_SCHEME):]
+        elif socket_path.startswith(UNIX_ADDRESS_STREAM_SCHEME):
+            valid_socket_kinds = [socket.SOCK_STREAM]
+            socket_path = socket_path[len(UNIX_ADDRESS_STREAM_SCHEME):]
+        elif socket_path.startswith(UNIX_ADDRESS_SCHEME):
+            socket_path = socket_path[len(UNIX_ADDRESS_SCHEME):]
+
+        last_error = ValueError("Invalid socket path")
+        for socket_kind in valid_socket_kinds:
+            try:
+                # This will fail in python2.7
+                sk_name = socket_kind.name
+            except AttributeError:
+                sk_name = socket_kind
+
+            try:
+                sock = socket.socket(socket.AF_UNIX, socket_kind)
+                sock.settimeout(timeout)
+                cls._ensure_min_send_buffer_size(sock)
+                sock.connect(socket_path)
+                log.debug("Connected to socket %s with kind %s", socket_path, sk_name)
+                return sock
+            except Exception as e:
+                if sock is not None:
+                    sock.close()
+                log.debug("Failed to connect to %s with kind %s: %s", socket_path, sk_name, e)
+                if e.errno == errno.EPROTOTYPE:
+                    last_error = e
+                    continue
+                raise e
+        raise last_error
 
     @classmethod
     def _get_udp_socket(cls, host, port, timeout):
@@ -1253,7 +1287,7 @@ def _xmit_packet(self, packet, is_telemetry):
                 )
                 self.close_socket()
         except Exception as exc:
-            print("Unexpected error: %s", exc)
+            print("Unexpected error: ", exc)
             log.error("Unexpected error: %s", str(exc))
 
         if not is_telemetry and self._telemetry:

tests/integration/dogstatsd/test_statsd_sender.py

@@ -1,18 +1,23 @@
+from contextlib import closing
 import itertools
+import os
+import shutil
 import socket
+import tempfile
 from threading import Thread
+import uuid
 
 import pytest
 
 from datadog.dogstatsd.base import DogStatsd
 
 @pytest.mark.parametrize(
-    "disable_background_sender, disable_buffering, wait_for_pending, socket_timeout, stop",
-    list(itertools.product([True, False], [True, False], [True, False], [0, 1], [True, False])),
+    "disable_background_sender, disable_buffering, wait_for_pending, socket_timeout, stop, socket_kind",
+    list(itertools.product([True, False], [True, False], [True, False], [0, 1], [True, False], [socket.SOCK_DGRAM, socket.SOCK_STREAM])),
 )
-def test_sender_mode(disable_background_sender, disable_buffering, wait_for_pending, socket_timeout, stop):
+def test_sender_mode(disable_background_sender, disable_buffering, wait_for_pending, socket_timeout, stop, socket_kind):
     # Test basic sender operation with an assortment of options
-    foo, bar = socket.socketpair(socket.AF_UNIX, socket.SOCK_DGRAM, 0)
+    foo, bar = socket.socketpair(socket.AF_UNIX, socket_kind, 0)
     statsd = DogStatsd(
         telemetry_min_flush_interval=0,
         disable_background_sender=disable_background_sender,
@@ -101,3 +106,41 @@ def test_buffering_with_context():
     bar.settimeout(5)
     msg = bar.recv(8192)
     assert msg == b"first:1|c\n"
+
+@pytest.fixture()
+def socket_dir():
+    tempdir = tempfile.mkdtemp()
+    yield tempdir
+    shutil.rmtree(tempdir)
+
+@pytest.mark.parametrize(
+        "socket_prefix, socket_kind, success",
+        [
+            ("", socket.SOCK_DGRAM, True),
+            ("", socket.SOCK_STREAM, True),
+            ("unix://", socket.SOCK_DGRAM, True),
+            ("unix://", socket.SOCK_STREAM, True),
+            ("unixstream://", socket.SOCK_DGRAM, False),
+            ("unixstream://", socket.SOCK_STREAM, True),
+            ("unixgram://", socket.SOCK_DGRAM, True),
+            ("unixgram://", socket.SOCK_STREAM, False)
+        ]
+)
+def test_socket_connection(socket_dir, socket_prefix, socket_kind, success):
+    socket_path = os.path.join(socket_dir, str(uuid.uuid1()) + ".sock")
+    listener_socket = socket.socket(socket.AF_UNIX, socket_kind)
+    listener_socket.bind(socket_path)
+
+    if socket_kind == socket.SOCK_STREAM:
+        listener_socket.listen(1)
+
+    with closing(listener_socket):
+        statsd = DogStatsd(
+            socket_path = socket_prefix + socket_path
+        )
+
+        if success:
+            assert statsd.get_socket() is not None
+        else:
+            with pytest.raises(socket.error):
+                statsd.get_socket()