Comment 1 for bug 1522879

lxd init is already implemented and in the archive, it's command line interface will remain identical, it's just a bit buggy in 0.23 but as far as mapping things into cloud-init, it's good to go.

Init options:
    --auto
        Automatic (non-interactive) mode
    --network-address ADDRESS
        Address to bind LXD to (default: none)
    --network-port PORT
        Port to bind LXD to (default: 8443)
    --storage-backend NAME
        Storage backend to use (zfs or dir, default: dir)
    --storage-create-device DEVICE
        Setup device based storage using DEVICE
    --storage-create-loop SIZE
        Setup loop based storage with SIZE in GB
    --storage-pool NAME
        Storage pool to use or create
    --trust-password PASSWORD
        Password required to add new clients

Those should probably be exposed as is through cloud-init and then, for those which were set, passed to lxd init along with the --auto flag.