[enhancement]: lxd config user.meta-data may disappear, investigate alternatives using cloud-init.vendor-data

[blackboxsw]

pycloudlib currently leverages a now undocumented lxd config feature user.meta-data to inject public-ssh-keys into every launched lxd instance to allow for SSH into the VM during boot in the absence of cloud-init.user-data.

Look to leverage cloud-init.vendor-data if possible, the caveat being that instance launches will have to take into account:

• LXD kvm-based launches setup a common profile which uses cloud-init.vendor-data to setup the lxd agent in Bionic, so instance launch would need to merge with existing cloud-init.vendor-data in profile configs if defined
• instance launches which provide user-data with ssh_authorized_keys: values in config would need to append to any cloud-specific authorized keys defined.

[hamistao]

Hi! LXD team member here :D

It came to my attention that most datasources provide some mechanism for communicating instance meta-data to cloud-init.

Currently user.meta-data still fills that role in LXD, but I don't see what practical purpose it has today. Perhaps if this is really needed for some reason we could think of ways to improve this functionality. As user.meta-data is vaguely named, not validated in any way within LXD and also not documented.

I hope we can shed some light on this topic and find a way forward for both our teams.