Dragonfly and Nydus

Install Dragonfly and the Nydus snapshotter by following the upstream guide: Dragonfly Helm charts installation.

The rest of this page covers only what is different on Kairos.

Keep the snapshotter state across reboots

The Nydus snapshotter keeps its state under /var/lib/nydus-snapshotter. On Kairos, /var is an ephemeral overlay, so that directory is wiped on every boot unless you make it persistent. Add it to CUSTOM_BIND_MOUNTS in your cloud-config:

#cloud-config

stages:
  rootfs:
    - name: "Persist the Nydus snapshotter state"
      environment_file: /run/cos/custom-layout.env
      environment:
        CUSTOM_BIND_MOUNTS: "/var/lib/nydus-snapshotter"

You can put this in the cloud-config you install with, or drop it in a file under /oem/ on a running node. It takes effect on the next boot. The directory is then bind mounted from the persistent partition.

CUSTOM_BIND_MOUNTS takes a space-separated list, and the last value written wins. If you already set it elsewhere, including through install.bind_mounts, add /var/lib/nydus-snapshotter to that list instead of adding a second entry.

See Bind mounts for how custom mounts work.