Address default is not a valid ip network

[Christian Dohm]

I'm setting up a Raspberry Pi 4B with the newest Ubuntu 22.04.1 LTS Server image for arm64, as delivered by the rpi-imager v1.7.2, via cloud-init facilities.

On first and all subsequent system startups, configuring the network fails with the following error message in "/var/log/cloud-init-output.log":
---
Cloud-init v. 22.2-0ubuntu1~22.04.3 running 'init-local' at Sun, 11 Sep 2022 17:44:58 +0000. Up 13.83 seconds.
2022-09-11 17:44:58,854 - network_state.py[ERROR]: Address default is not a valid ip network
2022-09-11 17:44:58,854 - util.py[WARNING]: failed stage init-local
failed run of stage init-local
------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/cloudinit/cmd/main.py", line 740, in status_wrapper
    ret = functor(name, args)
  File "/usr/lib/python3/dist-packages/cloudinit/cmd/main.py", line 410, in main_init
    init.apply_network_config(bring_up=bring_up_interfaces)
  File "/usr/lib/python3/dist-packages/cloudinit/stages.py", line 937, in apply_network_config
    return self.distro.apply_network_config(
  File "/usr/lib/python3/dist-packages/cloudinit/distros/__init__.py", line 231, in apply_network_config
    network_state = parse_net_config_data(netconfig)
  File "/usr/lib/python3/dist-packages/cloudinit/net/network_state.py", line 1056, in parse_net_config_data
    nsi.parse_config(skip_broken=skip_broken)
  File "/usr/lib/python3/dist-packages/cloudinit/net/network_state.py", line 278, in parse_config
    self.parse_config_v2(skip_broken=skip_broken)
  File "/usr/lib/python3/dist-packages/cloudinit/net/network_state.py", line 327, in parse_config_v2
    handler(self, command)
  File "/usr/lib/python3/dist-packages/cloudinit/net/network_state.py", line 720, in handle_ethernets
    subnets = self._v2_to_v1_ipcfg(cfg)
  File "/usr/lib/python3/dist-packages/cloudinit/net/network_state.py", line 880, in _v2_to_v1_ipcfg
    _normalize_route(
  File "/usr/lib/python3/dist-packages/cloudinit/net/network_state.py", line 1019, in _normalize_route
    _normalize_net_keys(
  File "/usr/lib/python3/dist-packages/cloudinit/net/network_state.py", line 953, in _normalize_net_keys
    raise ValueError(f"Address {addr} is not a valid ip address")
ValueError: Address default is not a valid ip address
------------------------------------------------------------
Cloud-init v. 22.2-0ubuntu1~22.04.3 running 'init' at Sun, 11 Sep 2022 17:45:00 +0000. Up 15.80 seconds.
ci-info: +++++++++++++++++++++++++++Net device info++++++++++++++++++++++++++++
ci-info: +--------+-------+-----------+-----------+-------+-------------------+
ci-info: | Device | Up | Address | Mask | Scope | Hw-Address |
ci-info: +--------+-------+-----------+-----------+-------+-------------------+
ci-info: | eth0 | False | . | . | . | <lan-mac-address> |
ci-info: | lo | True | 127.0.0.1 | 255.0.0.0 | host | . |
ci-info: | lo | True | ::1/128 | . | host | . |
ci-info: | wlan0 | False | . | . | . | <wifi-mac-addrss> |
ci-info: +--------+-------+-----------+-----------+-------+-------------------+
ci-info: +++++++++++++++++++Route IPv6 info+++++++++++++++++++
ci-info: +-------+-------------+---------+-----------+-------+
ci-info: | Route | Destination | Gateway | Interface | Flags |
ci-info: +-------+-------------+---------+-----------+-------+
ci-info: +-------+-------------+---------+-----------+-------+
---

The contents of "/boot/network-config" were generated with Terraform's yamlencode() function:
---
version: 2
"ethernets":
  "eth0":
    "addresses":
    - "<ipv4-classc-ip>/24"
    - "<ipv6ll-address>/64"
    "dhcp4": false
    "dhcp6": false
    "match":
      "driver":
      - "bcmgenet"
      - "smsc95xx"
      - "lan78xx"
    "nameservers":
      "addresses":
      - "<ipv4-gw-address>"
      "search":
      - "<some.domain>"
    "routes":
    - "to": "default"
      "via": "<ipv4-gw-address>"
    "set-name": "eth0"
---

[Christian Dohm (chris1294832)]

Interestingly, when the string "default" is changed to "0/0", the message becomes

---
Cloud-init v. 22.2-0ubuntu1~22.04.3 running 'init-local' at Tue, 09 Aug 2022 12:05:25 +0000. Up 12.50 seconds.
2022-08-09 12:05:26,677 - network_state.py[ERROR]: Address 0/0 is not a valid ip network
2022-08-09 12:05:26,679 - util.py[WARNING]: failed stage init-local
failed run of stage init-local
------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/cloudinit/cmd/main.py", line 740, in status_wrapper
    ret = functor(name, args)
  File "/usr/lib/python3/dist-packages/cloudinit/cmd/main.py", line 410, in main_init
    init.apply_network_config(bring_up=bring_up_interfaces)
  File "/usr/lib/python3/dist-packages/cloudinit/stages.py", line 937, in apply_network_config
    return self.distro.apply_network_config(
  File "/usr/lib/python3/dist-packages/cloudinit/distros/__init__.py", line 231, in apply_network_config
    network_state = parse_net_config_data(netconfig)
  File "/usr/lib/python3/dist-packages/cloudinit/net/network_state.py", line 1056, in parse_net_config_data
    nsi.parse_config(skip_broken=skip_broken)
  File "/usr/lib/python3/dist-packages/cloudinit/net/network_state.py", line 278, in parse_config
    self.parse_config_v2(skip_broken=skip_broken)
  File "/usr/lib/python3/dist-packages/cloudinit/net/network_state.py", line 327, in parse_config_v2
    handler(self, command)
  File "/usr/lib/python3/dist-packages/cloudinit/net/network_state.py", line 720, in handle_ethernets
    subnets = self._v2_to_v1_ipcfg(cfg)
  File "/usr/lib/python3/dist-packages/cloudinit/net/network_state.py", line 880, in _v2_to_v1_ipcfg
    _normalize_route(
  File "/usr/lib/python3/dist-packages/cloudinit/net/network_state.py", line 1019, in _normalize_route
    _normalize_net_keys(
  File "/usr/lib/python3/dist-packages/cloudinit/net/network_state.py", line 953, in _normalize_net_keys
    raise ValueError(f"Address {addr} is not a valid ip address")
ValueError: Address 0/0 is not a valid ip address
------------------------------------------------------------
---

[Christian Dohm (chris1294832)]

It does indeed work as expected when the 'to' field is set to "0.0.0.0/0".

[Simon Chopin (schopin)]

The "default" value as a valid route destination has been added to netplan a year ago as part of the deprecation of the gateway[46] fields: https://github.com/canonical/netplan/pull/216

The issue seems to be that cloud-init, which also parses a subset of the network config format, hasn't picked up this modification. Thus, the bug isn't in netplan per se.

I'm a bit surprised though, as I thought the cloud-init network config parser wasn't used if netplan was available on the system?

[James Falcon (falcojr)]

Until recently, cloud-init would still parse the v2 config to ensure it's valid before passing it on to netplan. This was recently fixed in https://github.com/canonical/cloud-init/pull/1650 and will be available in cloud-init 22.3.1.

This bug is also a duplicate, so I will be marking it as such.