Nix package manager install (single user) on Fedora Silverblue

Nix_package_manager_on_Fedora_Silverblue.md

Nix package manager on Fedora Silverblue

Warning

Disable composefs or enable root.transient before install and use nix on Fedora Silverblue 42. Do not mix both. Use just one method. I prefer enabling root.transient.

• With composefs disabled

  sudo sed -i 's/,ro//' /etc/fstab
  
  sudo rpm-ostree kargs --append='ostree.prepare-root.composefs=0' --reboot

• With root.transient enabled

  sudo tee /etc/ostree/prepare-root.conf <<'EOL'
  [composefs]
  enabled = yes
  [root]
  transient = true
  EOL
  
  rpm-ostree initramfs-etc --reboot --track=/etc/ostree/prepare-root.conf

Install nix

curl --proto '=https' --tlsv1.2 -sSf -L https://install.determinate.systems/nix | \
    sh -s -- install ostree --no-confirm --persistence=/var/lib/nix

Add nix unstable channel

nix-channel --add https://nixos.org/channels/nixpkgs-unstable nixpkgs
nix-channel --update

Fix sudo

echo "Defaults  secure_path = /nix/var/nix/profiles/default/bin:/nix/var/nix/profiles/default/sbin:$(sudo printenv PATH)" | sudo tee /etc/sudoers.d/nix-sudo-env

Old way (Obsolete)

• This is a single user install.

• For multi user install and without changing selinux mode: https://gist.github.com/matthewpi/08c3d652e7879e4c4c30bead7021ff73

• Please note that these instructions are not offically supported or condoned by Nix and are not guaranteed to always work, but from my testing everything seems to work perfectly fine.

• Change SELinux mode to permissive

  sudo setenforce Permissive
  sudo sed -i 's/SELINUX=enforcing/SELINUX=permissive/' /etc/selinux/config

• Create the nix directory in a persistent location

  sudo mkdir /var/lib/nix
  sudo chown $USER:$USER /var/lib/nix

• /etc/systemd/system/[email protected]

  [Unit]
  Description=Enable mount points in / for ostree
  ConditionPathExists=!%f
  DefaultDependencies=no
  Requires=local-fs-pre.target
  After=local-fs-pre.target
  
  [Service]
  Type=oneshot
  ExecStartPre=chattr -i /
  ExecStart=mkdir -p '%f'
  ExecStopPost=chattr +i /

• /etc/systemd/system/nix.mount

  [Unit]
  Description=Nix Package Manager
  DefaultDependencies=no
  After[email protected]
  Wants[email protected]
  Before=sockets.target
  After=ostree-remount.service
  BindsTo=var.mount
  
  [Mount]
  What=/var/lib/nix
  Where=/nix
  Options=bind
  Type=none
  
  [Install]
  WantedBy=local-fs.target

• Enable and mount the nix mount.

  # Ensure systemd picks up the newly created units
  sudo systemctl daemon-reload
  # Enable the nix mount on boot.
  sudo systemctl enable nix.mount
  # Mount the nix mount now.
  sudo systemctl start nix.mount

• Install Nix

  sh <(curl -L https://nixos.org/nix/install) --no-daemon

• Load Nix into your environment. Enable bash/fish/zhs completion for nix installed commands

  Load Nix into your environment. The installer modified ~/.bash_profile, but it isn't used when you start a terminal from desktop, it's only used when using a full shell login with bash -l, which doesn't happen on silverblue.

  tee --append $HOME/.bashrc <<EOF
  # Nix Package Manager
  if [ -e $HOME/.nix-profile/etc/profile.d/nix.sh ]; then
      source $HOME/.nix-profile/etc/profile.d/nix.sh;
  fi
  EOF

• Links:

  • https://tecadmin.net/how-to-disable-selinux-on-fedora/
  • https://gist.github.com/matthewpi/08c3d652e7879e4c4c30bead7021ff73
  • https://gist.github.com/queeup/26e36c6e3e701c0ba96c17dc5e5251be

Strange indeed. My instances works with disabled composefs. I will investigate. Thank you both of you for reporting this problem.

This didn't work for me, either, but following the directions here (making my own Kinoite with a /nix) did work:
DeterminateSystems/nix-installer#1445 (comment)

With composefs enabled root subvolume mount options in /etc/fstab are ignored. But with composefs disabled root subvolume mounted as ro (readonly). This is not like that before with Silverblue 41 etc. Silverblue 42 install add ro flag for root mount. So we need to mount rw or erase ro flag from /etc/fstab.

That why disabling composefs not working.

sudo sed -i 's/subvol=root,compress=zstd:1,ro/subvol=root,compress=zstd:1/' /etc/fstab

sudo rpm-ostree kargs --append='ostree.prepare-root.composefs=0' --reboot

after these two command it should work. I will update my howto accordantly.