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.

Author: ddrthall

datadog/dogstatsd/aggregator.py

@@ -55,8 +55,8 @@ def flush_aggregated_sampled_metrics(self):
         return metrics
 
     def get_context(self, name, tags):
-        tags_str = ",".join(tags) if tags is not None else ""
-        return "{}:{}".format(name, tags_str)
+        tags_str = u",".join(tags) if tags is not None else ""
+        return u"{}:{}".format(name, tags_str)
 
     def count(self, name, value, tags, rate, timestamp=0):
         return self.add_metric(

datadog/dogstatsd/base.py

@@ -13,6 +13,7 @@
 import os
 import socket
 import errno
+import struct
 import threading
 import time
 from threading import Lock, RLock
@@ -49,6 +50,11 @@
 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_BUFFERING_FLUSH_INTERVAL = 0.3
 MIN_FLUSH_INTERVAL = 0.0001
@@ -495,6 +501,36 @@ def socket_path(self, path):
                 self._transport = "uds"
                 self._max_payload_size = self._max_buffer_len or UDS_OPTIMAL_PAYLOAD_LENGTH
 
+    @property
+    def socket(self):
+        return self._socket
+
+    @socket.setter
+    def socket(self, new_socket):
+        self._socket = new_socket
+        if new_socket:
+            try:
+                self._socket_kind = new_socket.getsockopt(socket.SOL_SOCKET, socket.SO_TYPE)
+                return
+            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
+
+    @property
+    def telemetry_socket(self):
+        return self._telemetry_socket
+
+    @telemetry_socket.setter
+    def telemetry_socket(self, t_socket):
+        self._telemetry_socket = t_socket
+        if t_socket:
+            try:
+                self._telemetry_socket_kind = t_socket.getsockopt(socket.SOL_SOCKET, socket.SO_TYPE)
+                return
+            except AttributeError:  # _telemetry_socket can't have a kind if it doesn't have sockopts
+                log.info("Unexpected telemetry socket provided with no support for getsockopt")
+        self._telemetry_socket_kind = None
+
     def enable_background_sender(self, sender_queue_size=0, sender_queue_timeout=0):
         """
         Use a background thread to communicate with the dogstatsd server.
@@ -738,11 +774,37 @@ 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:
+            # py2 stores socket kinds differently than py3, determine the name independently from version
+            sk_name = {socket.SOCK_STREAM: "stream", socket.SOCK_DGRAM: "datagram"}[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):
@@ -1243,14 +1305,22 @@ def _xmit_packet_with_telemetry(self, packet):
                 self.packets_dropped_writer += 1
 
     def _xmit_packet(self, packet, is_telemetry):
+        socket_kind = None
         try:
             if is_telemetry and self._dedicated_telemetry_destination():
                 mysocket = self.telemetry_socket or self.get_socket(telemetry=True)
+                socket_kind = self._telemetry_socket_kind
             else:
                 # If set, use socket directly
                 mysocket = self.socket or self.get_socket()
+                socket_kind = self._socket_kind
 
-            mysocket.send(packet.encode(self.encoding))
+            encoded_packet = packet.encode(self.encoding)
+            if socket_kind == socket.SOCK_STREAM:
+                mysocket.sendall(struct.pack('<I', len(encoded_packet)))
+                mysocket.sendall(encoded_packet)
+            else:
+                mysocket.send(encoded_packet)
 
             if not is_telemetry and self._telemetry:
                 self.packets_sent += 1
@@ -1283,13 +1353,19 @@ 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:
             self.bytes_dropped_writer += len(packet)
             self.packets_dropped_writer += 1
 
+        # if in stream mode we need to shut down the socket; we can't recover from a
+        # partial send
+        if socket_kind == socket.SOCK_STREAM:
+            log.debug("Confirming socket closure after error streaming")
+            self.close_socket()
+
         return False
 
     def _send_to_buffer(self, packet):

tests/integration/dogstatsd/test_statsd_sender.py

@@ -1,18 +1,24 @@
+from contextlib import closing
 import itertools
+import os
+import shutil
 import socket
+import struct
+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,
@@ -24,7 +30,11 @@ def test_sender_mode(disable_background_sender, disable_buffering, wait_for_pend
     statsd._reset_telemetry()
 
     def reader_thread():
-        msg = bar.recv(8192)
+        if socket_kind == socket.SOCK_DGRAM:
+            msg = bar.recv(8192)
+        else:
+            size = struct.unpack("<I", bar.recv(4))[0]
+            msg = bar.recv(size)
         assert msg == b"test.metric:1|c\n"
 
     t = Thread(target=reader_thread, name="test_sender_mode/reader_thread")
@@ -49,6 +59,25 @@ def test_set_socket_timeout():
     statsd.close_socket()
     assert statsd.get_socket().gettimeout() == 1
 
+def test_stream_cleanup():
+    foo, _ = socket.socketpair(socket.AF_UNIX, socket.SOCK_STREAM, 0)
+
+    foo.settimeout(0)
+    statsd = DogStatsd(disable_buffering=True)
+    statsd.socket = foo
+    statsd.increment("test", 1)
+    statsd.increment("test", 1)
+    statsd.increment("test", 1)
+    assert statsd.socket is not None
+
+    foo.setsockopt(socket.SOL_SOCKET, socket.SO_SNDBUF, 1) # different os's have different mins, e.g. this sets the buffer size to 2304 on certain linux variants
+
+    with pytest.raises(socket.error):
+        foo.sendall(os.urandom(5000)) # pre-emptively clog the buffer
+
+    statsd.increment("test", 1)
+
+    assert statsd.socket is None
 
 @pytest.mark.parametrize(
     "disable_background_sender, disable_buffering",
@@ -101,3 +130,41 @@ 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()