Netplan can't bind to more than 512 IPv4 addresses

[Martin]

As per title. Migrating a proxy server from 16.04 Ubuntu to 18.04 and hitting issues with netplan. I've had no issues binding to 900~ IPv4 addresses via interfaces.d on 16.04.

My netplan folder has two config files. One for the server static IP -

network:
  version: 2
  ethernets:
    eth0:
      addresses: [10.80.11.76/16]
      gateway4: 10.80.0.1
      nameservers:
        addresses: [10.80.0.11,10.80.0.12]

And then a secondary one that is generated by this bash script:

#!/bin/bash
cat << EOF
network:
  version: 2
  bridges:
EOF
 for i in {100..999}; do
  echo " br0:"
  echo " addresses: [10.70.${i::1}.$((10#${i:1:3}))/16]"
  echo " interfaces: [vlan1]"
 done
echo " vlans:"
cat << EOF
    vlan1:
      accept-ra: no
      id: 1
      link: eth0
EOF

This breaks upon reboot and binds to nothing instead.
Changing the for to only go from 100 to 600 (slightly below the 512 limit) works just fine.
As a note, this is done on an LXD container.

Testing the configuration gives no output in any case and just returns a status code 0 every time I tried it.

https://netplan.io/faq#test-a-configuration

Workaround: Make netplan only create the br0 interface and add the IPs via 'ip addr add' elsewhere.

[Martin (c0rn3j)]

Configs as an attachment since the tracker eats spaces and tabs.