https://channels.nixos.org/nixos-24.05/latest-nixos-minimal-x86_64-linux.iso

Flash the image to an USB drive using Rufus or use Ventoy. Please note that using these tools will erase all data on the USB drive, so make sure to back up any important files before proceeding.

You can install it in a VM using ProxmoxVE or VMWare Workstation Pro as well.

• Change your keyboard layout with sudo loadkeys de if you don't have an ANSI keyboard.
• Type sudo passwd to enter a password and activate the root account.

• Type in ip a to see your IP-address and connect via SSH from another machine with ssh root@<IPFromTheNixOS-BackupServer>.

• Use ls /sys/firmware/efi to check if you are in UEFI or BIOS mode. If you receive ls: cannot access '/sys/firmware/efi': No such file or directory you are in BIOS mode.
• Plugin the backup disks now, if not already connected. Partition and format them as needed.
• Display your disks with lsblk -f and adjust the device paths /dev/sdX in the following commands with your desired drive(s) to install NixOS on.

parted --script /dev/sdX mklabel gpt && \
parted --script /dev/sdX mkpart primary fat32 1MB 512MB --align optimal && \
parted --script /dev/sdX set 1 esp on && \
parted --script /dev/sdX mkpart primary ext4 512MB 10.982GB --align optimal && \
parted --script /dev/sdX mkpart primary linux-swap 10.982GB 11.980GB --align optimal && \
mkfs.ext4 -L NIXOS /dev/sdX2 && \
mkswap -L SWAP /dev/sdX3 && \
swapon /dev/sdX3 && \
mkfs.fat -F 32 -n BOOT /dev/sdX1 && \
mount /dev/disk/by-label/NIXOS /mnt && \
mkdir -p /mnt/boot && \
mount -o umask=077 /dev/disk/by-label/BOOT /mnt/boot && \
mkdir -p /mnt/etc/nixos/

parted --script /dev/sdX mklabel msdos && \
parted --script /dev/sdX mkpart primary ext4 1MB 11GB --align optimal && \
parted --script /dev/sdX mkpart primary linux-swap 11GB 12GB --align optimal && \
mkfs.ext4 -L NIXOS /dev/sdX1 && \
mkswap -L SWAP /dev/sdX2 && \
swapon /dev/sdX2 && \
mount /dev/disk/by-label/NIXOS /mnt && \
mkdir -p /mnt/etc/nixos/

• Open a gitMinimal shell with nix-shell -p gitMinimal, clone this repo with git clone https://github.com/DieSchoeneWolke/NixOS-BackupServer && exit.

• Copy all files to /mnt/etc/nixos/ with cp -R ./NixOS-BackupServer/* /mnt/etc/nixos/ && cd /mnt/etc/nixos/.

• Edit the network configuration file with nano network.nix and replace it with the values for your network card.

• Create a user on the machine with read/write/execute permissions on the directories you want to back up.

• Generate two ssh-keyfiles. One on the machine you are configuring this server from with a keyphrase and insert the content of the public keyfile in the users.nix file and change the initialPassword in the file. The other ssh-keyfile should be created on this server with ssh-keygen -o -a 100 -t ed25519 and saved to /root/.ssh/rsync.prvk without a passphrase. Insert the content of the public keyfile in the machine you want to backup at /home/<UserYouCreated>/.ssh/known_hosts. chmod 600 <YourPrivateKeyfile> to set appropriate permissions for the current user on the private keyfile.

• Edit the backup.nix file and adjust the backup jobs to your needs.

• If you are in BIOS mode, edit system.nix, remove the UEFI bootloader section,uncomment the BIOS section and replace the device name with your root drive.

• Generate a hardware-configuration.nix file with nixos-generate-config --root /mnt and replace /dev/disk/by-uuid with /dev/disk/by-label. Use /dev/disk/by-label/NIXOS on the drive with fsType = "ext4"; and if you are in UEFI mode /dev/disk/by-label/BOOT on the drive with fsType = "vfat"; and /dev/disk/by-label/SWAP at the device in swapDevices. Append "nofail" in the options of your backup drives.

• Install NixOS with nixos-install --no-root-passwd.

• reboot the system.

• Reconnect with ssh -i <PrivateKeyfileFromTheConfiguringMachine> backupper@<IPFromTheNixOS-BackupServer> and the keyphrase you provided while creating the keyfile.

• Change the password with passwd.

• Connect to the machine you want to back up from the NixOS-BackupServer with sudo ssh -i /root/.ssh/rsync.prvk <UsernameFromTheBackupMachine>@<IPFromTheBackupMachine> once to add it to the known_hosts file.

• systemctl list-timers --all to see if the timers for your backup jobs are running.

• Email notification upon backup completion. As of now this only works for manual jobs since systemd-timers use an empty environment and don't support MAILTO like cron. Use the mail.nix from my NixOS-SMTP repository to use msmtp as SMTP client.