I did a talk about my experience going down the Anycast rabbit hole side quest at The Long Con this weekend. In preparation for this talk I built a fleet of new Debian 13 nodes, using the Debian provided KVM image which supports cloud-init.

Getting More Loopbacks

Sooooooo… I’ve been using Debian for a fairly long time, since Potato or Woody. I’ve been using /etc/network/interfaces for configuration of loopbacks and static IPs since the beginning of time. It took me a good hour to get two loopback addresses bound. interfaces actually seemed to work for a single one, but the second was missing completely.

Searching for the default network management tool didn’t seem to give me any results so I searched around to see what options were available, and what files might be on disk.

It turns out if you’re cloning a debian cloud image and using cloud-init, the networking is being done with netplan now. Ubuntu has required this to do a static IPv6 address for a while now, so this wasn’t completely foreign to me.

The file I created on both nodes to add two service addresses.

# /etc/netplan/01-lo.yaml
network:
  version: 2
  renderer: networkd
  ethernets:
    lo:
      match:
        name: lo
      addresses:
        - 192.0.2.2/32
        - 192.0.2.3/32

sudo netplan generate && sudo netplan apply brings these addresses up, and a reboot confirms they’re there after reboot too.

Everything else I setup basically according to my most recent anycast post.