Comment 7 for bug 1582323

cloud-init allows kernel command line to have yaml inline that contributes to cloud-config.
 http://bazaar.launchpad.net/~cloud-init-dev/cloud-init/trunk/view/head:/doc/examples/kernel-cmdline.txt

That woudl require an SRU to get the change functional though. As currently the kernel command line config is consumed after /etc/cloud/cloud.cfg but before /etc/cloud/cloud.cfg.d/* and it is /etc/cloud/cloud.cfg.d/90_dpkg.cfg that defines the standard list of datasources.

So, with a small SRUable change like: http://paste.ubuntu.com/16684929/

we could then have maas pass on the kernel command line a token like:
  cc:{'datasource_list': ['MAAS']}end_cc

basically that is:
  "cc:" + json.dumps({'datasource_list': ['MAAS']}) + "end_cc"