Can I customize the root partition disk size? Or mount a data volume at /nix?

[ghost]

👋 I'm exploring using lima and nix for a reproducible development environment.
I am running into the root partition filling up quickly (2GB).

Can I customize the root partition disk size? Or mount a data volume at /nix?

I am using alpine as the base image and then installing nix.

Nix uses /nix to store everything related to itself and packaging. AFAIK, you cannot configure that.
That path quickly fills up:

df -h /nix
Filesystem                Size      Used Available Use% Mounted on
tmpfs                     1.9G      1.9G         0 100% /

Yet I see my configured 100GB of space in /tmp/data:

df -h /tmp/
Filesystem                Size      Used Available Use% Mounted on
/dev/disk/by-label/data-volume
                         97.9G    421.7M     92.5G   0% /mnt/data

Thanks!

[jandubois]

This is specific to Alpine (because we use an ISO and not a regular image):

The "diffdisk" in this case is indeed a separate data volume, and the following directories have been moved to the persisted disk: /etc, /home, /tmp, /usr/local, and /var/lib.

You will notice that changes to any other part of the filesystem will be reverted by an instance restart because the OS runs from a tmpfs.

However, it should be easy enough to move your /nix directory to the persistent volume too:

# mv /nix /mnt/data
# mkdir /nix
# mount --bind /mnt/data/nix /nix

You will also want to create a system provisioning script in your lima.yaml to repeat the mount command on each boot.