Claim IPv6 is unsupported if no interface with IPv6 configured

When IPv6 is supported by glibc but no interface
is configured to use ipv6 (because the ipv6 module
is not loaded), skip ipv6 related checks.

Change-Id: I15aaf3d01f0f51bdc0bd29f30728ca2ab8b5c30a

nova/tests/test_test_utils.py

@@ -14,6 +14,11 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import errno
+import socket
+
+import fixtures
+
 from nova import db
 from nova import test
 from nova.tests import utils as test_utils
@@ -39,3 +44,28 @@ class TestUtilsTestCase(test.TestCase):
         # The challenge here is to define what exactly such a structure
         # must look like.
         pass
+
+    def test_ipv6_supported(self):
+        self.assertIn(test_utils.is_ipv6_supported(), (False, True))
+
+        def fake_open(path):
+            raise IOError
+
+        def fake_socket_fail(x, y):
+            e = socket.error()
+            e.errno = errno.EAFNOSUPPORT
+            raise e
+
+        def fake_socket_ok(x, y):
+            return
+
+        with fixtures.MonkeyPatch('socket.socket', fake_socket_fail):
+            self.assertFalse(test_utils.is_ipv6_supported())
+
+        with fixtures.MonkeyPatch('socket.socket', fake_socket_ok):
+            with fixtures.MonkeyPatch('sys.platform', 'windows'):
+                self.assertTrue(test_utils.is_ipv6_supported())
+
+            with fixtures.MonkeyPatch('sys.platform', 'linux2'):
+                with fixtures.MonkeyPatch('__builtin__.open', fake_open):
+                    self.assertFalse(test_utils.is_ipv6_supported())

nova/tests/utils.py

@@ -17,6 +17,7 @@
 import errno
 import platform
 import socket
+import sys
 
 from oslo.config import cfg
 
@@ -177,7 +178,7 @@ def killer_xml_body():
 
 
 def is_ipv6_supported():
-    has_ipv6_support = True
+    has_ipv6_support = socket.has_ipv6
     try:
         s = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)
     except socket.error as e:
@@ -185,4 +186,14 @@ def is_ipv6_supported():
             has_ipv6_support = False
         else:
             raise
+
+    # check if there is at least one interface with ipv6
+    if has_ipv6_support and sys.platform.startswith('linux'):
+        try:
+            with open('/proc/net/if_inet6') as f:
+                if not f.read():
+                    has_ipv6_support = False
+        except IOError:
+            has_ipv6_support = False
+
     return has_ipv6_support