NixOS on an Oracle Free Tier Ampere machine. Success!

Oracle does not offer a NixOS image, so it’s little complex to set up instance here.

Create your machine

1. Register for Oracle Cloud always-free tier. To avoid instance creation limits, need to add payment method (charge $100 temporary) and enable pay-as-go plan.

2. Create an instance. I’m using image Ubuntu 22.04. Settings (this utilizes all free tier resources):

• Image: Ubuntu 22.04
• Shape: VM.Standard.A1.Flex, 4 OCPU, 24GB RAM
• Boot volume: 200GB, up to 20 VPU
• SSH key: add your public key

3. Prepare ubuntu machine, install nix and kexec:

sudo apt update; sudo apt upgrade -y; reboot; sudo reboot
# ... wait until reboot and reconnect again ssh ...
sh <(curl -L https://nixos.org/nix/install) --daemon # details -> n, sudo -> y
# Logout and SSH again to get a fresh Nix-enabled shell.

Prepare an in-memory NixOS system to perform the installation from

We’re now following https://nixos.wiki/wiki/Install_NixOS_on_a_Server_With_a_Different_Filesystem and it’s a little more advanced:

git clone https://github.com/iturdikulov/nix-tests
cd nix-tests/kexec
# edit configuration.nix to add your pub ssh key into authorizedKeys.keys
vi configuration.nix
# validate key
cat configuration.nix | grep authorizedKeys.keys
# build tarball with nixos installatioon, can take 5-10+ minutes
nix-build '<nixpkgs/nixos>' -A config.system.build.kexec_tarball -I nixos-config=./configuration.nix
# untar and run kexec_nixos
tar -xf ./result/tarball/nixos-system-aarch64-linux.tar.xz
sudo ./kexec_nixos

Once you’ve seen that + kexec -e line, you can terminate your SSH connection (the server won’t reply, just hit enter, ~, . to tell the client to close everything. The server will come back (can take 5-10+ minutes) with a different host key, so you’ll want to clean up your known_hosts before sshing again:

ip=...
ssh-keygen -R ${ip?}
ssh root@${ip?} # use -i if you need specify key

Installing NixOS to the disk

Now we’re root on an im-memory NixOS system. If we rebooted the machine at this point, it would boot back into Ubuntu. We don’t want that, we need to install NixOS on disk, so we’ll immediately start deleting the existing partitions and mold the disk to our liking.

I have own guide to install NixOS, don’t forget to enable SSH with your key!

NOTE: if you see some message, like reboot scheduled, you can cancel it with this command shutdown -c.

Guide: GitHub - Inom-Turdikulov/dotfiles: And I say hey, what’s going on?

Alternative way (not tested)

GitHub - elitak/nixos-infect