fix (MQ): support IPv4-only broker hostnames

src/DIRAC/Resources/MessageQueue/StompMQConnector.py

@@ -122,16 +122,14 @@ def setupConnection(self, parameters=None):
 
         try:
             # Get IP addresses of brokers
-            # Start with the IPv6, and randomize it
-            ipv6_addrInfo = socket.getaddrinfo(host, port, socket.AF_INET6, socket.SOCK_STREAM)
-            random.shuffle(ipv6_addrInfo)
-            # Same with IPv4
-            ipv4_addrInfo = socket.getaddrinfo(host, port, socket.AF_INET, socket.SOCK_STREAM)
-            random.shuffle(ipv4_addrInfo)
-
-            # Create the host_port tuples, keeping the ipv6 in front
+            addrInfo = socket.getaddrinfo(host, port, socket.AF_UNSPEC, socket.SOCK_STREAM)
+            random.shuffle(addrInfo)
+            # Prefer IPv6 while preserving the randomized order within each address family
+            addrInfo.sort(key=lambda address: address[0] != socket.AF_INET6)
+
+            # Create the host_port tuples, keeping IPv6 in front
             host_and_ports = []
-            for _family, _socktype, _proto, _canonname, sockaddr in ipv6_addrInfo + ipv4_addrInfo:
+            for _family, _socktype, _proto, _canonname, sockaddr in addrInfo:
                 host_and_ports.append((sockaddr[0], sockaddr[1]))
 
             connectionArgs.update({"host_and_ports": host_and_ports})

src/DIRAC/Resources/MessageQueue/test/Test_StompMQConnector.py

@@ -0,0 +1,60 @@
+"""Unit tests for the STOMP message queue connector."""
+
+import socket
+from unittest import mock
+
+from DIRAC.Resources.MessageQueue.StompMQConnector import StompMQConnector
+
+
+@mock.patch("DIRAC.Resources.MessageQueue.StompMQConnector.random.shuffle")
+@mock.patch("DIRAC.Resources.MessageQueue.StompMQConnector.stomp.Connection")
+@mock.patch("DIRAC.Resources.MessageQueue.StompMQConnector.socket.getaddrinfo")
+def test_setup_connection_with_ipv4_only(getaddrinfo, connection, _shuffle):
+    getaddrinfo.return_value = [
+        (socket.AF_INET, socket.SOCK_STREAM, socket.IPPROTO_TCP, "", ("192.0.2.1", 61613)),
+    ]
+
+    result = StompMQConnector().setupConnection({"Host": "mq.example", "VHost": "/"})
+
+    assert result["OK"]
+    getaddrinfo.assert_called_once_with("mq.example", 61613, socket.AF_UNSPEC, socket.SOCK_STREAM)
+    connection.assert_called_once_with(
+        vhost="/",
+        keepalive=True,
+        timeout=60,
+        heartbeats=(15_000, 15_000),
+        reconnect_sleep_initial=1,
+        reconnect_sleep_increase=0.5,
+        reconnect_sleep_max=120,
+        reconnect_sleep_jitter=0.1,
+        reconnect_attempts_max=1e4,
+        host_and_ports=[("192.0.2.1", 61613)],
+    )
+
+
+@mock.patch("DIRAC.Resources.MessageQueue.StompMQConnector.random.shuffle")
+@mock.patch("DIRAC.Resources.MessageQueue.StompMQConnector.stomp.Connection")
+@mock.patch("DIRAC.Resources.MessageQueue.StompMQConnector.socket.getaddrinfo")
+def test_setup_connection_prefers_ipv6(getaddrinfo, connection, _shuffle):
+    getaddrinfo.return_value = [
+        (socket.AF_INET, socket.SOCK_STREAM, socket.IPPROTO_TCP, "", ("192.0.2.1", 61613)),
+        (socket.AF_INET6, socket.SOCK_STREAM, socket.IPPROTO_TCP, "", ("2001:db8::1", 61613, 0, 0)),
+    ]
+
+    result = StompMQConnector().setupConnection({"Host": "mq.example", "VHost": "/"})
+
+    assert result["OK"]
+    assert connection.call_args.kwargs["host_and_ports"] == [
+        ("2001:db8::1", 61613),
+        ("192.0.2.1", 61613),
+    ]
+
+
+@mock.patch("DIRAC.Resources.MessageQueue.StompMQConnector.socket.getaddrinfo")
+def test_setup_connection_reports_resolution_failure(getaddrinfo):
+    getaddrinfo.side_effect = socket.gaierror(socket.EAI_NONAME, "Name or service not known")
+
+    result = StompMQConnector().setupConnection({"Host": "missing.example", "VHost": "/"})
+
+    assert not result["OK"]
+    assert "Name or service not known" in result["Message"]