cloud-init-dev team mailing list archive

[Ryan Harper <ryan.harper@xxxxxxxxxxxxx>]

Thanks.  I swear I just was working on a branch for this very issue but I can't find any duplicate bugs.

Inline question on what to do if bond/vlan sets MTU > than underlying device?

Diff comments:

> diff --git a/tests/unittests/test_net.py b/tests/unittests/test_net.py
> index de4e7f4..e2bbb84 100644
> --- a/tests/unittests/test_net.py
> +++ b/tests/unittests/test_net.py
> @@ -2856,6 +2856,97 @@ USERCTL=no
>          self._compare_files_to_expected(entry['expected_sysconfig'], found)
>          self._assert_headers(found)
>  
> +    def test_from_v2_vlan_mtu(self):
> +        """verify mtu gets rendered on bond when source is netplan."""
> +        v2data = {
> +            'version': 2,
> +            'ethernets': {'eno1': {}},
> +            'vlans': {
> +                'eno1.1000': {
> +                    'addresses': ["192.6.1.9/24"],
> +                    'id': 1000, 'link': 'eno1', 'mtu': 1495}}}
> +        expected = {
> +            'ifcfg-eno1': textwrap.dedent("""\
> +                BOOTPROTO=none
> +                DEVICE=eno1
> +                NM_CONTROLLED=no
> +                ONBOOT=yes
> +                STARTMODE=auto
> +                TYPE=Ethernet
> +                USERCTL=no
> +                """),
> +            'ifcfg-eno1.1000': textwrap.dedent("""\
> +                BOOTPROTO=none
> +                DEVICE=eno1.1000
> +                IPADDR=192.6.1.9
> +                MTU=1495
> +                NETMASK=255.255.255.0
> +                NM_CONTROLLED=no
> +                ONBOOT=yes
> +                PHYSDEV=eno1
> +                STARTMODE=auto
> +                TYPE=Ethernet
> +                USERCTL=no
> +                VLAN=yes
> +                """)
> +            }
> +        self._compare_files_to_expected(
> +            expected, self._render_and_read(network_config=v2data))
> +
> +    def test_from_v2_bond_mtu(self):
> +        """verify mtu gets rendered on bond when source is netplan."""
> +        v2data = {
> +            'version': 2,
> +            'bonds': {
> +                'bond0': {'addresses': ['10.101.8.65/26'],
> +                          'interfaces': ['enp0s0', 'enp0s1'],
> +                          'mtu': 1334,
> +                          'parameters': {}}}
> +        }
> +        expected = {
> +            'ifcfg-bond0': textwrap.dedent("""\
> +                BONDING_MASTER=yes
> +                BONDING_SLAVE0=enp0s0
> +                BONDING_SLAVE1=enp0s1
> +                BOOTPROTO=none
> +                DEVICE=bond0
> +                IPADDR=10.101.8.65
> +                MTU=1334

I'm not familiar with sysconfig runtime here;  I know from ifupdown/xenial we had issues where if you set an MTU larger than what the underlying device had (say 9000, devices default to 1500);  What do we expect here?

In netplan; I believe the mtu is also applied to the underlying device; but I suspect that's not the case in sysconfig (as it's not in ifupdown).

If sysconfig does require the underlying devices to have an mtu to match the bond or vlan, then should we render that (even if as in your config, the user doesn't specify the MTU)?

Note that your examples of an mtu lower than 1500 already work since the bond slices the packet by MTU which fits 1500 but this doesn't work for MTU > 1500.

> +                NETMASK=255.255.255.192
> +                NM_CONTROLLED=no
> +                ONBOOT=yes
> +                STARTMODE=auto
> +                TYPE=Bond
> +                USERCTL=no
> +                """),
> +            'ifcfg-enp0s0': textwrap.dedent("""\
> +                BONDING_MASTER=yes
> +                BOOTPROTO=none
> +                DEVICE=enp0s0
> +                MASTER=bond0
> +                NM_CONTROLLED=no
> +                ONBOOT=yes
> +                SLAVE=yes
> +                STARTMODE=auto
> +                TYPE=Bond
> +                USERCTL=no
> +                """),
> +            'ifcfg-enp0s1': textwrap.dedent("""\
> +                BONDING_MASTER=yes
> +                BOOTPROTO=none
> +                DEVICE=enp0s1
> +                MASTER=bond0
> +                NM_CONTROLLED=no
> +                ONBOOT=yes
> +                SLAVE=yes
> +                STARTMODE=auto
> +                TYPE=Bond
> +                USERCTL=no
> +                """)
> +        }
> +        self._compare_files_to_expected(
> +            expected, self._render_and_read(network_config=v2data))
> +
>  
>  class TestOpenSuseSysConfigRendering(CiTestCase):
>  


-- 
https://code.launchpad.net/~smoser/cloud-init/+git/cloud-init/+merge/370280
Your team cloud-init commiters is requested to review the proposed merge of ~smoser/cloud-init:fix/1836949-mtu-lost-in-translation into cloud-init:master.