basic support for Linux tap devices

our project needs to deploy taps using os-net-config utility. leverage
a dedicated type from ifcfg implementation.

Change-Id: Iaf4294bec6c21f130c7a149d0f45d3be53c1c9cc

etc/os-net-config/samples/linux_tap.json

@@ -0,0 +1,8 @@
+{ "network_config": [
+    {
+        "type": "linux_tap",
+        "name": "tap0",
+        "use_dhcp": true
+    }
+  ]
+}

etc/os-net-config/samples/linux_tap.yaml

@@ -0,0 +1,6 @@
+network_config:
+  -
+    type: linux_tap
+    name: tap0
+    use_dhcp: true
+

os_net_config/__init__.py

@@ -118,6 +118,8 @@ class NetConfig(object):
             self.add_contrail_vrouter(obj)
         elif isinstance(obj, objects.ContrailVrouterDpdk):
             self.add_contrail_vrouter_dpdk(obj)
+        elif isinstance(obj, objects.LinuxTap):
+            self.add_linux_tap(obj)
 
     def add_route_table(self, route_table):
         """Add a route table object to the net config object.
@@ -284,6 +286,15 @@ class NetConfig(object):
         raise NotImplementedError(
             "add_contrail_vrouter_dpdk is not implemented.")
 
+    def add_linux_tap(self, linux_tap):
+        """Add a LinuxTap object to the net config object.
+
+        :param linux_tap:
+            The LinuxTap object to add.
+        """
+        raise NotImplementedError(
+            "add_linux_tap is not implemented.")
+
     def apply(self, cleanup=False):
         """Apply the network configuration.
 

os_net_config/impl_ifcfg.py

@@ -1114,6 +1114,18 @@ class IfcfgNetConfig(os_net_config.NetConfig):
             self._add_rules(contrail_vrouter_dpdk.name,
                             contrail_vrouter_dpdk.rules)
 
+    def add_linux_tap(self, linux_tap):
+        """Add a LinuxTap object to the net config object
+
+        :param linux_tap:
+           The LinuxTap object to add
+        """
+        logger.info('adding Linux TAP interface: %s'
+                    % linux_tap.name)
+        data = self._add_common(linux_tap)
+        data += "TYPE=Tap\n"
+        self.interface_data[linux_tap.name] = data
+
     def generate_ivs_config(self, ivs_uplinks, ivs_interfaces):
         """Generate configuration content for ivs."""
 

os_net_config/objects.py

@@ -91,6 +91,8 @@ def object_from_json(json):
         return SriovPF.from_json(json)
     elif obj_type == "sriov_vf":
         return SriovVF.from_json(json)
+    elif obj_type == "linux_tap":
+        return LinuxTap.from_json(json)
 
 
 def _get_required_field(json, name, object_name, datatype=None):
@@ -1848,3 +1850,37 @@ class ContrailVrouterDpdk(_BaseOpts):
                                    bond_mode=bond_mode,
                                    bond_policy=bond_policy, driver=driver,
                                    cpu_list=cpu_list, vlan_id=vlan_id)
+
+
+class LinuxTap(_BaseOpts):
+    """Base class for Linux tap Interface.
+
+    TAP, namely network TAP, simulates a link layer device and operates in
+    layer 2 carrying Ethernet frames.
+    A user space program may also pass packets into a TAP device. In this
+    case the TAP device delivers (or "injects") these packets to the
+    operating-system network stack thus emulating their reception from an
+    external source.
+    """
+    def __init__(self, name, use_dhcp=False, use_dhcpv6=False, addresses=None,
+                 routes=None, rules=None, mtu=None, primary=False,
+                 nic_mapping=None, persist_mapping=False, defroute=True,
+                 dhclient_args=None, dns_servers=None, nm_controlled=False,
+                 onboot=True, domain=None, members=None):
+        super(LinuxTap, self).__init__(name, use_dhcp, use_dhcpv6,
+                                       addresses, routes, rules, mtu,
+                                       primary, nic_mapping,
+                                       persist_mapping, defroute,
+                                       dhclient_args, dns_servers,
+                                       nm_controlled, onboot, domain)
+
+    @staticmethod
+    def from_json(json):
+        name = _get_required_field(json, 'name', 'LinuxTap')
+
+        (_use_dhcp, _use_dhcpv6, _addresses, _routes, _rules, _mtu, _primary,
+         nic_mapping, persist_mapping, _defroute, _dhclient_args, _dns_servers,
+         _nm_controlled, _onboot,
+         _domain) = opts = _BaseOpts.base_opts_from_json(json)
+
+        return LinuxTap(name, *opts)

os_net_config/schema.yaml

@@ -1077,6 +1077,43 @@ definitions:
           - members
         additionalProperties: False
 
+    linux_tap:
+        type: object
+        properties:
+            type:
+                enum: ["linux_tap"]
+            name:
+                $ref: "#/definitions/string_or_param"
+            # common options:
+            use_dhcp:
+                $ref: "#/definitions/bool_or_param"
+            use_dhcpv6:
+                $ref: "#/definitions/bool_or_param"
+            addresses:
+                $ref: "#/definitions/list_of_address"
+            routes:
+                $ref: "#/definitions/list_of_route"
+            rules:
+                $ref: "#/definitions/list_of_rule"
+            mtu:
+                $ref: "#/definitions/int_or_param"
+            nic_mapping:
+                $ref: "#/definitions/nic_mapping"
+            persist_mapping:
+                $ref: "#/definitions/bool_or_param"
+            defroute:
+                $ref: "#/definitions/bool_or_param"
+            dhclient_args:
+                $ref: "#/definitions/string_or_param"
+            dns_servers:
+                $ref: "#/definitions/list_of_ip_address_string_or_param"
+            nm_controlled:
+                $ref: "#/definitions/bool_or_param"
+        required:
+          - type
+          - name
+        additionalProperties: False
+
     linux_bridge:
         type: object
         properties:
@@ -1533,4 +1570,5 @@ items:
       - $ref: "#/definitions/vpp_bond"
       - $ref: "#/definitions/contrail_vrouter"
       - $ref: "#/definitions/contrail_vrouter_dpdk"
+      - $ref: "#/definitions/linux_tap"
 minItems: 1

os_net_config/tests/test_impl_ifcfg.py

@@ -603,6 +603,15 @@ DRIVER=uio_pci_generic
 CPU_LIST=2,3
 """
 
+_LINUX_TAP_IFACE = """# This file is autogenerated by os-net-config
+DEVICE=tap0
+ONBOOT=yes
+HOTPLUG=no
+NM_CONTROLLED=no
+PEERDNS=no
+BOOTPROTO=none
+TYPE=Tap
+"""
 _SRIOV_PF_IFCFG = """# This file is autogenerated by os-net-config
 DEVICE=enp3s0f0
 ONBOOT=yes
@@ -1142,6 +1151,13 @@ class TestIfcfgNetConfig(base.TestCase):
             self.provider.interface_data['vhost0'])
         self.assertEqual('', self.get_route_config('vhost0'))
 
+    def test_add_linux_tap(self):
+        tap = objects.LinuxTap('tap0', nm_controlled=False)
+        self.provider.add_linux_tap(tap)
+        self.assertEqual(
+            _LINUX_TAP_IFACE,
+            self.provider.interface_data['tap0'])
+
     def test_add_vlan(self):
         vlan = objects.Vlan('em1', 5)
         self.provider.add_vlan(vlan)

os_net_config/tests/test_objects.py

@@ -2443,3 +2443,18 @@ class TestOvsRequiredObjects(base.TestCase):
         expected = 'OvsDpdkPort cannot be created as OpenvSwitch is not ' \
                    'installed.'
         self.assertIn(expected, six.text_type(err))
+
+
+class TestLinuxTap(base.TestCase):
+
+    def test_linux_tap_from_json(self):
+        data = """{
+"type": "linux_tap",
+"name": "tap0",
+"nm_controlled": false
+}
+"""
+
+        linux_tap = objects.object_from_json(json.loads(data))
+        self.assertEqual("tap0", linux_tap.name)
+        self.assertEqual(False, linux_tap.nm_controlled)