Nix package manager in fly.io Sprites

Recently I stumbled upon Fly.io’s Sprites.

Tangled uses nix (the package manager) and since I had my development setup for Tangled in a docker container(TODO: add footnote) it was a good excuse to play around with them.

How to install

First, choose the multi-user installation:
sh <(curl --proto '=https' --tlsv1.2 -L https://nixos.org/nix/install) --daemon

Note: The installer will complain, that you don’t have systemd installed.
This is expected—we will handle that next.

Next, add the nix daemon to the services of your Sprite:

sprite-env services create nix-daemon \
    --cmd sudo \
    --args /nix/var/nix/profiles/default/bin/nix-daemon

That’s all. Yep.

Errors I encountered

nix develop hangs on copying [something] to the store

This was really annoying, because the Sprite would just crash after a few minutes stuck at this step.

The issue ended up being that the user is not trusted (in the nix context).

To fix it:

• Add trusted-users = root sprite to /etc/nix/nix.conf
• Restart the nix daemon (using sprite-env)

nix store info hangs at Store URL: daemon

The issue here is most likely, that the daemon is not running as root.

You can verify this with ls -la /nix/var/nix/daemon-socket/socket. The owner should be root (not sprite).

To fix this, make sure you started the daemon with sudo.