Summary: SSH keys etc do not get set correctly due to incorrect MTU handling.
When network_data.json gets downloaded from cloud-init, eg. http://169.254.169.254/openstack/2018-08-27/network_data.json
The 'links' node might contain an mtu that is set to 'null'
This documented in the following Openstack document, https://docs.openstack.org/nova/latest/user/metadata.html
Ideally Openstack should return the correct MTU, but in my environment it does not.
VyOS does not like this and the cc_vyos.py script returns an error.
See the following error:
2024-03-08 16:18:20,552 - cc_vyos.py[DEBUG]: Configured SSH public key for user: vyos
2024-03-08 16:18:20,552 - cc_vyos.py[DEBUG]: Configuring network using Cloud-init networking config version 1
2024-03-08 16:18:20,552 - cc_vyos.py[DEBUG]: Setting MAC for eth0: xx:xx:xx:xx:xx:xx
2024-03-08 16:18:20,552 - cc_vyos.py[DEBUG]: Setting MTU for eth0: None
2024-03-08 16:18:20,557 - handlers.py[DEBUG]: finish: modules-config/config-vyos: FAIL: running config-vyos with frequency once-per-instance
2024-03-08 16:18:20,557 - util.py[WARNING]: Running module vyos (<module 'cloudinit.config.cc_vyos' from '/usr/lib/python3/dist-packages/cloudinit/config/cc_vyos.py'>) failed
2024-03-08 16:18:20,558 - util.py[DEBUG]: Running module vyos (<module 'cloudinit.config.cc_vyos' from '/usr/lib/python3/dist-packages/cloudinit/config/cc_vyos.py'>) failed
Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/cloudinit/stages.py", line 1087, in _run_modules
run_name, mod.handle, func_args, freq=freq
File "/usr/lib/python3/dist-packages/cloudinit/cloud.py", line 55, in run
return self._runners.run(name, functor, args, freq, clear_on_fail)
File "/usr/lib/python3/dist-packages/cloudinit/helpers.py", line 185, in run
results = functor(*args)
File "/usr/lib/python3/dist-packages/cloudinit/config/cc_vyos.py", line 1158, in handle
set_config_interfaces_v1(config, interface_config)
File "/usr/lib/python3/dist-packages/cloudinit/config/cc_vyos.py", line 470, in set_config_interfaces_v1
set_ether_mtu(config, iface_name, iface_config['mtu'])
File "/usr/lib/python3/dist-packages/cloudinit/config/cc_vyos.py", line 275, in set_ether_mtu
if max_mtu and max_mtu < mtu:
TypeError: '<' not supported between instances of 'int' and 'NoneType'
2024-03-08 16:18:20,558 - stages.py[DEBUG]: Running module write_files (<module 'cloudinit.config.cc_write_files' from '/usr/lib/python3/dist-packages/cloudinit/config/cc_write_files.py'>) with frequency once-per-instanceThis causes the SSH keys and other parts of the user data to not get set correctly, which results in you being unable to log in to the router after re-deploy.
I have worked around this error myself by commenting line 470 in https://github.com/vyos/vyos-cloud-init/blob/equuleus/cloudinit/config/cc_vyos.py#L470
and just letting DEFAULT_ETH_MTU of 1500 be set instead.
This is clearly not intended behavior and needs to be fixed. The last working version I was upgrading from was 1.3.2.