[22:12] <cmm_> Good day everyone.  I'm using cloud-init to set up virtual machines using NoCloud-net and I need to vary setup based on whether the VM is booted with BIOS or EFI.  I was wondering if it was possible to add variables to instance-data[-sensitive].json early on, say using a boothook or the like.  That way later on I can use Jinja2 templates.
[22:18] <cmm_> What I've tried:  Add a custom user-data file to /etc/cloud/cloud.cfg.d/, hoping it'd show up in merged_cfg (it doesn't).  I have control over the /metadata seed provided over the network, but there doesn't seem to be any way to tell cloud-init to send values in an HTTP query string so I can feed them back through ds.meta_data.
[22:29] <cmm_> I've read the docs here as well.  https://cloudinit.readthedocs.io/en/latest/topics/instancedata.html