Code cleanup for docker interface creation

Fix #819

Signed-off-by: Julien Duponchelle <julien@gns3.net>

gns3server/compute/docker/docker_vm.py

@@ -642,11 +642,10 @@ class DockerVM(BaseNode):
                                                                                                            adapter_number=adapter_number))
 
         for index in range(4096):
-            if "veth-gns3-e{}".format(index) not in psutil.net_if_addrs():
-                adapter.ifc = "eth{}".format(str(index))
+            if "tap-gns3-e{}".format(index) not in psutil.net_if_addrs():
                 adapter.host_ifc = "tap-gns3-e{}".format(str(index))
                 break
-        if not hasattr(adapter, "ifc"):
+        if adapter.host_ifc is None:
             raise DockerError("Adapter {adapter_number} couldn't allocate interface on Docker container '{name}'. Too many Docker interfaces already exists".format(name=self.name,
                                                                                                                                                                     adapter_number=adapter_number))
 

tests/compute/docker/test_docker_vm.py

@@ -742,7 +742,7 @@ def test_add_ubridge_connection_no_free_interface(loop, vm):
     with pytest.raises(DockerError):
 
         # We create fake ethernet interfaces for docker
-        interfaces = ["veth-gns3-e{}".format(index) for index in range(4096)]
+        interfaces = ["tap-gns3-e{}".format(index) for index in range(4096)]
 
         with patch("psutil.net_if_addrs", return_value=interfaces):
             loop.run_until_complete(asyncio.async(vm._add_ubridge_connection(nio, 0, 42)))