NAS-106037 / 12.0 / Make MTU of VNet interfaces configurable (iocage#1095)

* Add configuration parameters for default MTU on VNet device creation, as well as specific MTU for each VNet device. Default behaviour is the old behaviour (default of 1500, or whatever the bridge we're connecting to is set to)

* Add a space after a comma (travis fussiness)

* Mock a hard code variable for unit test use only

* More travis fussiness

* Update ioc_json.py

Remove a couple of f-strings that didn't have variables within them.

* Remove self.unit_test hack for vnet_default_mtu

- Instead of having dummy data in the implementation, hack the test to implement the needed IOCStart.get() method fragment we need to test.
- Also upgrade the cirrus.yml to use FreeBSD 11.3 rather than 11.2 - hopefully this fixes the failing unit test

* Update cirrus-ci to FreeBSD 11.3-STABLE

* Revert "Update cirrus-ci to FreeBSD 11.3-STABLE"

This reverts commit 3473e6b.

* Lets see if the latest 11.3 snapshot works with CirrusCI

According to https://cirrus-ci.org/guide/FreeBSD/ the 11.3-RELEASE doesn't work with Cirrus-CI / gCloud. But apparently the stable snapshots do. Lets see.

* 11.2 is EOL. Use 11.3 in jail.

* Use the latest 11-STABLE family image, not a specific dated snapshot (thanks to asomers for the tip)

Author: nathanjrobertson

.cirrus.yml

@@ -1,5 +1,5 @@
 freebsd_instance:
-  image: freebsd-11-2-release-amd64
+  image_family: freebsd-11-3-snap
 
 iocage_tests_task:
   create_pool_script:

iocage_lib/ioc_json.py

@@ -434,7 +434,7 @@ def __init__(self, location, checking_datasets, silent, callback):
     @staticmethod
     def get_version():
         """Sets the iocage configuration version."""
-        version = '27'
+        version = '28'
 
         return version
 
@@ -898,6 +898,13 @@ def check_config(self, conf, default=False):
         if not conf.get('min_dyn_devfs_ruleset'):
             conf['min_dyn_devfs_ruleset'] = '1000'
 
+        # Version 28 keys
+        for x in range(0, 4):
+            if not conf.get(f"vnet{x}_mtu"):
+                conf[f"vnet{x}_mtu"] = 'auto'
+        if not conf.get("vnet_default_mtu"):
+            conf["vnet_default_mtu"] = '1500'
+
         if not default:
             conf.update(jail_conf)
 
@@ -1236,6 +1243,11 @@ def retrieve_default_props():
             'plugin_name': 'none',
             'plugin_repository': 'none',
             'min_dyn_devfs_ruleset': '1000',
+            'vnet0_mtu': 'auto',
+            'vnet1_mtu': 'auto',
+            'vnet2_mtu': 'auto',
+            'vnet3_mtu': 'auto',
+            'vnet_default_mtu': '1500',
         }
 
     def check_default_config(self):
@@ -2152,6 +2164,11 @@ def json_check_prop(self, key, value, conf, default=False):
             'plugin_name': ('string', ),
             'plugin_repository': ('string', ),
             'min_dyn_devfs_ruleset': ('string', ),
+            "vnet0_mtu": ("string", ),
+            "vnet1_mtu": ("string", ),
+            "vnet2_mtu": ("string", ),
+            "vnet3_mtu": ("string", ),
+            "vnet_default_mtu": ("string", ),
         }
 
         zfs_props = {

iocage_lib/ioc_start.py

@@ -1180,10 +1180,12 @@ def start_network_interface_vnet(
             nic, bridge = nic_def.split(":")
 
             try:
-                if not nat_addr:
+                if self.get(f"{nic}_mtu") != 'auto':
+                    membermtu = self.get(f"{nic}_mtu")
+                elif not nat_addr:
                     membermtu = self.find_bridge_mtu(bridge)
                 else:
-                    membermtu = '1500'
+                    membermtu = self.get('vnet_default_mtu')
 
                 dhcp = self.get('dhcp')
 
@@ -1571,7 +1573,7 @@ def find_bridge_mtu(self, bridge):
 
         memberif = self.get_bridge_members(bridge)
         if not memberif:
-            return '1500'
+            return self.get('vnet_default_mtu')
 
         membermtu = iocage_lib.ioc_common.checkoutput(
             ["ifconfig", memberif[0]]

tests/conftest.py

@@ -38,7 +38,7 @@ def pytest_addoption(parser):
         help='Specify a zpool to use.'
     )
     parser.addoption(
-        '--release', action='store', default='11.2-RELEASE',
+        '--release', action='store', default='11.3-RELEASE',
         help='Specify a RELEASE to use.'
     )
     parser.addoption(

tests/unit_tests/1000_lib_start_test.py

@@ -52,7 +52,16 @@ def test_should_return_default_mtu_if_no_members(mock_checkoutput):
     mock_checkoutput.side_effect = [bridge_with_no_members_if_config,
                                     member_if_config]
 
-    mtu = ioc_start.IOCStart("", "", unit_test=True).find_bridge_mtu('bridge0')
+    # IOCStart.get() is not implemented in test mode. We need it for this test.
+    # So provide a dummy implementation which gives us the default MTU.
+    def _mock_iocstart_get(prop):
+        if prop=='vnet_default_mtu':
+            return "1500"
+        raise AttributeError(prop)
+
+    iocs = ioc_start.IOCStart("", "", unit_test=True)
+    iocs.get = _mock_iocstart_get
+    mtu = iocs.find_bridge_mtu('bridge0')
     assert mtu == '1500'
     mock_checkoutput.called_with(["ifconfig", "bridge0"])