OpenStack: Link-Local IPv6 metadata address invalid without postfixed interface (no metadata with IPv6-only network)

[frittentheke]

Bug report

The IPv6 metadata address http://[fe80::a9fe:a9fe] being a link-local address, requires an interface.
Used as is urllib3 reports the address to be an invalid argument.

See e.g. #1805 (comment)

Steps to reproduce the problem

• Start a VM on an IPv6-only network
• http://[fe80::a9fe:a9fe] will see the invalid argument exception from urllib3
• http://169.254.169.254 will timeout, as there is no IPv4 connectivity
• No metadata, no VM provisioning

Environment details

• Cloud-init version:
• Operating System Distribution: Ubuntu 24.04
• Cloud provider, platform or installer type: OpenStack Zed (private Cloud)

cloud-init logs

2024-06-19 02:05:09,291 - url_helper.py[WARNING]: Exception(s) [UrlError("HTTPConnectionPool(host='fe80::a9fe:a9fe', port=80): Max retries exceeded with url: /openstack (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7f345fd8e760>: Failed to establish a new connection: [Errno 22] Invalid argument'))"), UrlError("HTTPConnectionPool(host='169.254.169.254', port=80): Max retries exceeded with url: /openstack (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7f3460abf160>: Failed to establish a new connection: [Errno 101] Network is unreachable'))")] during request to http://169.254.169.254/openstack, raising last exception