This issue is to keep track of the findings for cloud-init/http. We're still not sure if it's worth working on it but atleast we save all infos in one place.

On systems that support smbios/kernel command line we could leverage it to set the uri of our server to download the cloud-init config -> https://cloudinit.readthedocs.io/en/latest/reference/datasources/nocloud.html

On hyperv/vfkit there is no way to set smbios params.
An alternative could be to attach an ISO as we do now containing a user-data file having the #include directive with the url of our server feeding the actual user-data.
E.g.

#include 
http://<ip-host>:<port>/configs/user-data

Cloud-init will read the user-data file in the ISO, will download the file mentioned in the include from our server and will configure the VM.
Cloud-init reads 2 user-data and merge them automatically without us creating a mime archive.