Archived
333 lines
6.5 KiB
Markdown
333 lines
6.5 KiB
Markdown
# Nix Auto Installer
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This repository builds a custom NixOS installer environment that can automatically
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install any host exposed by a separate NixOS flake.
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The installer provides a small NixOS netboot/install environment with SSH access,
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Git support, and an interactive installation script. When the `nixos` user logs
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in, it runs `/etc/auto-install.sh`, discovers available hosts from the target
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flake, allows the operator to choose a system profile, applies the matching
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Disko storage configuration, installs NixOS, and reboots.
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The installer is designed for a mixed environment where different machines may
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have different storage layouts, including Proxmox VMs, Linode instances, and
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physical hardware. Disk layout is no longer hardcoded in the installer; it is
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defined by each host's NixOS configuration using Disko.
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## Repository Layout
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* `flake.nix`
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* Defines the installer build outputs.
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* Builds an `install-iso` image using `nixos-generators`.
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* Builds netboot kernel, initrd, and iPXE scripts.
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* `installer.nix`
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* Defines the installer environment.
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* Enables SSH access.
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* Configures Git access to the target flake repository.
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* Creates the `nixos` and `root` users.
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* Provides the generated `/etc/auto-install.sh` installation script.
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The installed system configuration lives in a separate NixOS flake. Each target
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host is exposed through:
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```nix
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nixosConfigurations.<hostname>
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```
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and may optionally include a Disko storage configuration.
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## Requirements
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The build machine requires:
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* Nix installed with flakes enabled.
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* Network access to fetch flake inputs.
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* Ability to build NixOS images.
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The target machine requires:
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* Network connectivity during installation.
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* A disk defined by its Disko configuration.
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* SSH access or local console access.
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## Build The Installer ISO
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From the repository root:
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```sh
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nix build
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```
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The generated installer ISO will be available through the `result` symlink.
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The ISO is generated using:
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```nix
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nixos-generators.nixosGenerate {
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format = "install-iso";
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}
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```
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## Build Netboot Components
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The flake also exposes netboot components:
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```sh
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nix build .#netboot-ipxe
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nix build .#netboot-initrd
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nix build .#netboot-kernel
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```
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These can be used to PXE boot the installer environment.
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## Use The Installer
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1. Boot the generated ISO or netboot environment on the target machine.
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2. Log in as the `nixos` user.
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3. The login shell launches:
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```sh
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/etc/auto-install.sh
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```
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4. The installer queries the target flake:
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```text
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git+https://gitea.lan.ddnsgeek.com/beatzaplenty/nixos.git
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```
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5. Available installation profiles are discovered from:
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```nix
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nixosConfigurations
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```
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6. Select the host profile to install.
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7. Confirm the installation.
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8. The installer applies the selected host's Disko storage layout.
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9. NixOS is installed using the selected flake configuration.
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10. The system reboots into the installed OS.
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## Storage Management
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Disk partitioning is handled by Disko.
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The installer no longer contains hardcoded commands such as:
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```sh
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parted
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mkfs.ext4
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mkswap
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mount
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```
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Instead, each NixOS host defines its own storage layout.
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Example:
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```nix
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{
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disko.devices = {
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disk.main = {
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type = "disk";
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device = "/dev/sda";
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content = {
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type = "gpt";
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partitions = {
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root = {
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size = "-8G";
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content = {
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type = "filesystem";
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format = "ext4";
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mountpoint = "/";
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};
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};
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swap = {
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size = "100%";
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content = {
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type = "swap";
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};
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};
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};
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};
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};
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};
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}
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```
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This allows different hosts to define different layouts:
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* Proxmox VMs
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* Linode instances
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* Physical servers
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* ZFS systems
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* Future hardware-specific layouts
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A host without a Disko configuration will not be automatically partitioned.
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## Installer Process
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The generated `/etc/auto-install.sh` performs the following steps:
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1. Fetch available hosts from the configured NixOS flake.
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2. Present available `nixosConfigurations` as a menu.
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3. Confirm the selected installation target.
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4. Check whether the selected host has a Disko configuration.
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5. Run:
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```sh
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disko --mode destroy,format,mount --flake <flake>#<host>
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```
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6. Prepare `/mnt` using the Disko-generated mount configuration.
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7. Install NixOS:
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```sh
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nixos-install \
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--flake <flake>#<host> \
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--no-root-password
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```
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8. Remove temporary installation files.
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9. Reboot.
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## Configuration Notes
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The installer currently assumes:
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* Target flake:
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```text
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git+https://gitea.lan.ddnsgeek.com/beatzaplenty/nixos.git
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```
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* Host definitions are under:
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```nix
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nixosConfigurations
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```
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* The installer has network access before installation.
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* SSH is enabled.
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* Root SSH login is permitted.
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* The timezone is:
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```text
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Australia/Brisbane
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```
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* The target host is responsible for defining its own storage layout.
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Change these values in `installer.nix` if your environment differs.
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## Security Notes
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`installer.nix` currently contains:
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* Git credentials
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* Password hashes
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* SSH public keys
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Treat the repository and generated installer images as sensitive.
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For production use, consider replacing embedded credentials with:
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* Short-lived tokens
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* SSH deploy keys
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* External secrets management
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* Runtime credential injection
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## Safety Warnings
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This installer is destructive.
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The command:
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```sh
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disko --mode destroy,format,mount
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```
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will erase any disks defined by the selected host's Disko configuration.
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Always verify:
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* The selected host profile.
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* The Disko device paths.
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* The target machine.
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Never boot this installer on a machine containing important data unless the
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storage configuration has been reviewed.
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## Troubleshooting
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### No hosts appear in the menu
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Check that the installer can reach the flake repository:
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```sh
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nix eval --json \
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"git+https://gitea.lan.ddnsgeek.com/beatzaplenty/nixos.git#nixosConfigurations" \
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--apply builtins.attrNames
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```
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### Selected host has no Disko configuration
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The installer checks for:
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```nix
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config.disko.devices
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```
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Hosts without Disko storage definitions must either:
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* Add a Disko module, or
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* Be installed using another storage method.
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### Disko evaluation fails
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Check the selected host locally:
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```sh
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nix eval \
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".#nixosConfigurations.<host>.config.disko.devices"
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```
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### Installation fails fetching the flake
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Verify:
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* Network connectivity.
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* Git credentials.
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* Flake input availability.
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### Installer does not start automatically
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Run manually:
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```sh
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sudo /etc/auto-install.sh
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```
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