Merge "Make wsgi server uses systemd's NOTIFY_SOCKET"

swift/common/utils.py

@@ -5820,3 +5820,30 @@ def get_db_files(db_path):
             continue
         results.append(os.path.join(db_dir, f))
     return sorted(results)
+
+
+def systemd_notify(logger=None):
+    """
+    Notify the service manager that started this process, if it is
+    systemd-compatible, that this process correctly started. To do so,
+    it communicates through a Unix socket stored in environment variable
+    NOTIFY_SOCKET. More information can be found in systemd documentation:
+    https://www.freedesktop.org/software/systemd/man/sd_notify.html
+
+    :param logger: a logger object
+    """
+    msg = b'READY=1'
+    notify_socket = os.getenv('NOTIFY_SOCKET')
+    if notify_socket:
+        if notify_socket.startswith('@'):
+            # abstract namespace socket
+            notify_socket = '\0%s' % notify_socket[1:]
+        sock = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
+        with closing(sock):
+            try:
+                sock.connect(notify_socket)
+                sock.sendall(msg)
+                del os.environ['NOTIFY_SOCKET']
+            except EnvironmentError:
+                if logger:
+                    logger.debug("Systemd notification failed", exc_info=True)

swift/common/wsgi.py

@@ -45,7 +45,7 @@ from swift.common.swob import Request, wsgi_quote, wsgi_unquote, \
 from swift.common.utils import capture_stdio, disable_fallocate, \
     drop_privileges, get_logger, NullLogger, config_true_value, \
     validate_configuration, get_hub, config_auto_int_value, \
-    reiterate, clean_up_daemon_hygiene
+    reiterate, clean_up_daemon_hygiene, systemd_notify
 
 SIGNUM_TO_NAME = {getattr(signal, n): n for n in dir(signal)
                   if n.startswith('SIG') and '_' not in n}
@@ -1185,6 +1185,9 @@ def run_wsgi(conf_path, app_section, *args, **kwargs):
         os.write(reexec_signal_fd, str(os.getpid()).encode('utf8'))
         os.close(reexec_signal_fd)
 
+    # Finally, signal systemd (if appropriate) that process started properly.
+    systemd_notify(logger=logger)
+
     no_fork_sock = strategy.no_fork_sock()
     if no_fork_sock:
         run_server(conf, logger, no_fork_sock, global_conf=global_conf)

test/unit/common/test_utils.py

@@ -4372,6 +4372,69 @@ cluster_dfw1 = http://dfw1.host/v1/
             utils.load_pkg_resource(*args)
         self.assertEqual("Unhandled URI scheme: 'nog'", str(cm.exception))
 
+    def test_systemd_notify(self):
+        m_sock = mock.Mock(connect=mock.Mock(), sendall=mock.Mock())
+        with mock.patch('swift.common.utils.socket.socket',
+                        return_value=m_sock) as m_socket:
+            # No notification socket
+            m_socket.reset_mock()
+            m_sock.reset_mock()
+            utils.systemd_notify()
+            self.assertEqual(m_socket.call_count, 0)
+            self.assertEqual(m_sock.connect.call_count, 0)
+            self.assertEqual(m_sock.sendall.call_count, 0)
+
+            # File notification socket
+            m_socket.reset_mock()
+            m_sock.reset_mock()
+            os.environ['NOTIFY_SOCKET'] = 'foobar'
+            utils.systemd_notify()
+            m_socket.assert_called_once_with(socket.AF_UNIX, socket.SOCK_DGRAM)
+            m_sock.connect.assert_called_once_with('foobar')
+            m_sock.sendall.assert_called_once_with(b'READY=1')
+            self.assertNotIn('NOTIFY_SOCKET', os.environ)
+
+            # Abstract notification socket
+            m_socket.reset_mock()
+            m_sock.reset_mock()
+            os.environ['NOTIFY_SOCKET'] = '@foobar'
+            utils.systemd_notify()
+            m_socket.assert_called_once_with(socket.AF_UNIX, socket.SOCK_DGRAM)
+            m_sock.connect.assert_called_once_with('\0foobar')
+            m_sock.sendall.assert_called_once_with(b'READY=1')
+            self.assertNotIn('NOTIFY_SOCKET', os.environ)
+
+        # Test logger with connection error
+        m_sock = mock.Mock(connect=mock.Mock(side_effect=EnvironmentError),
+                           sendall=mock.Mock())
+        m_logger = mock.Mock(debug=mock.Mock())
+        with mock.patch('swift.common.utils.socket.socket',
+                        return_value=m_sock) as m_socket:
+            os.environ['NOTIFY_SOCKET'] = '@foobar'
+            m_sock.reset_mock()
+            m_logger.reset_mock()
+            utils.systemd_notify()
+            self.assertEqual(0, m_sock.sendall.call_count)
+            self.assertEqual(0, m_logger.debug.call_count)
+
+            m_sock.reset_mock()
+            m_logger.reset_mock()
+            utils.systemd_notify(logger=m_logger)
+            self.assertEqual(0, m_sock.sendall.call_count)
+            m_logger.debug.assert_called_once_with(
+                "Systemd notification failed", exc_info=True)
+
+        # Test it for real
+        sock = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
+        sock.settimeout(5)
+        sock.bind('\0foobar')
+        os.environ['NOTIFY_SOCKET'] = '@foobar'
+        utils.systemd_notify()
+        msg = sock.recv(512)
+        sock.close()
+        self.assertEqual(msg, b'READY=1')
+        self.assertNotIn('NOTIFY_SOCKET', os.environ)
+
 
 class ResellerConfReader(unittest.TestCase):