Comment 8 for bug 1991261

No problem; the user-data in use is as follows (I haven't bothered scrubbing anything because this is just the one I use for ephemeral testing; the password isn't remotely secure and isn't intended to be -- in fact it's public in my dotfiles repo somewhere!):

  #cloud-config

  hostname: miss-piggy

  chpasswd:
    expire: false
    list:
    - ubuntu:raspberry

  keyboard:
    model: pc105
    layout: gb
    options: ctrl:nocaps

  ssh_import_id:
  - lp:waveform

  apt:
    conf: |
      Acquire::http { Proxy "http://acng.waveform.org.uk:3142"; }

And the network-config is as follows (minus a ton of default comments):

  version: 2
  ethernets:
    eth0:
      dhcp4: true
      optional: true

I'd noticed the warnings about deprecation but they don't make much sense to me: "Use of a multiline string for this field is DEPRECATED" implies I'm using a multi-line string in chpasswd.list ... but it's a list, not a multi-line string.

On kernel command line parameters, the cmdline.txt on the boot partition contains:

  console=serial0,115200 dwc_otg.lpm_enable=0 console=tty1 root=LABEL=writable rootfstype=ext4 rootwait fixrtc quiet splash

This is the default on the Pi images. However, it does get manipulated by the bootloader, so this is what it looks like from /proc/cmdline after boot:

  coherent_pool=1M 8250.nr_uarts=1 snd_bcm2835.enable_headphones=0 snd_bcm2835.enable_headphones=1 snd_bcm2835.enable_hdmi=1 bcm2708_fb.fbwidth=1920 bcm2708_fb.fbheight=1080 bcm2708_fb.fbswap=1 smsc95xx.macaddr=DC:A6:32:31:6F:7C vc_mem.mem_base=0x3ec00000 vc_mem.mem_size=0x40000000 console=ttyS0,115200 dwc_otg.lpm_enable=0 console=tty1 root=LABEL=writable rootfstype=ext4 rootwait fixrtc quiet splash

In any case, I'm pretty confident there's no hostname specified on the kernel command line.