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# nixos # nixos
## Installation ## Installation
Follow the [NixOS manual](https://nixos.org/manual/nixos/stable/index.html#ch-installation) to obtain and boot Follow the [NixOS
the installation medium. Use the graphical ISO image since it ships with useful programs such as `nmtui`; the manual](https://nixos.org/manual/nixos/stable/index.html#ch-installation) to
installation can still be done through the terminal. obtain and boot the installation medium. Use the graphical ISO image since it
ships with useful programs such as `nmtui`; the installation can still be done
through the terminal.
### Disk Partitioning ### Disk Partitioning
For [impermanence](https://nixos.wiki/wiki/Impermanence), partitioning should be done as outlined in the [tmpfs For [impermanence](https://nixos.wiki/wiki/Impermanence), partitioning should
as root](https://elis.nu/blog/2020/05/nixos-tmpfs-as-root/) blogpost, but with `/nix` as a [LUKS-encrypted file be done as outlined in the [tmpfs as
system](https://nixos.org/manual/nixos/stable/index.html#sec-luks-file-systems). The boot partition will not be root](https://elis.nu/blog/2020/05/nixos-tmpfs-as-root/) blogpost, but with
encrypted, since that is poorly supported by systemd-boot. Persistent files will be saved under `/nix/persist`. To `/nix` as a [LUKS-encrypted file
find out which of our darlings will be erased on reboot do `tree -x /` or `ncdu -x /`. system](https://nixos.org/manual/nixos/stable/index.html#sec-luks-file-systems).
The boot partition will not be encrypted, since that is poorly supported by
systemd-boot. Persistent files will be saved under `/nix/persist`. To find out
which of our darlings will be erased on reboot do `tree -x /` or `ncdu -x /`.
The following is based on the [tmpfs as root](https://elis.nu/blog/2020/05/nixos-tmpfs-as-root/) blogpost, the NixOS The following is based on the [tmpfs as
manual's [partitioning](https://nixos.org/manual/nixos/stable/index.html#sec-installation-manual-partitioning), root](https://elis.nu/blog/2020/05/nixos-tmpfs-as-root/) blogpost, the NixOS
[formatting](https://nixos.orgmanual/nixos/stable/index.html#sec-installation-manual-partitioning-formatting) and manual's
[LUKS-Encrypted File Systems](https://nixos.org/manual/nixos/stable/index.html#sec-luks-file-systems) sections, [partitioning](https://nixos.org/manual/nixos/stable/index.html#sec-installation-manual-partitioning),
ArchWiki's [LVM on LUKS](https://wiki.archlinux.org/title/Dm-crypt/Encrypting_an_entire_system#LVM_on_LUKS), [formatting](https://nixos.orgmanual/nixos/stable/index.html#sec-installation-manual-partitioning-formatting)
the unofficial NixOS wiki [Full Disk Encryption](https://nixos.wiki/wiki/Full_Disk_Encryption), and [this GitHub and [LUKS-Encrypted File
Systems](https://nixos.org/manual/nixos/stable/index.html#sec-luks-file-systems)
sections, ArchWiki's [LVM on
LUKS](https://wiki.archlinux.org/title/Dm-crypt/Encrypting_an_entire_system#LVM_on_LUKS),
the unofficial NixOS wiki [Full Disk
Encryption](https://nixos.wiki/wiki/Full_Disk_Encryption), and [this GitHub
gist](https://gist.github.com/martijnvermaat/76f2e24d0239470dd71050358b4d5134). gist](https://gist.github.com/martijnvermaat/76f2e24d0239470dd71050358b4d5134).
We create a 1GiB EFI boot partition (`/dev/sda1`) and the rest will be our LUKS-encrypted volume: We create a 1GiB EFI boot partition (`/dev/sda1`) and the rest will be our
LUKS-encrypted volume:
```fish ```fish
# Create partition table # Create partition table
parted /dev/sda -- mklabel gpt parted /dev/sda -- mklabel gpt
@ -58,8 +69,10 @@ sda
└─vg-root ext4 1.0 nix └─vg-root ext4 1.0 nix
``` ```
Whereas the [NixOS manual](https://nixos.org/manual/nixos/stable/index.html#sec-installation-manual-installing) mounts Whereas the [NixOS
the newly-created `nixos` partition to `/mnt`, we will follow the _tmpfs as root_ blogpost and mount `/mnt` as `tmpfs`: manual](https://nixos.org/manual/nixos/stable/index.html#sec-installation-manual-installing)
mounts the newly-created `nixos` partition to `/mnt`, we will follow the _tmpfs
as root_ blogpost and mount `/mnt` as `tmpfs`:
```fish ```fish
mount -t tmpfs none /mnt mount -t tmpfs none /mnt
mount --mkdir /dev/disk/by-label/BOOT /mnt/boot mount --mkdir /dev/disk/by-label/BOOT /mnt/boot
@ -68,44 +81,62 @@ mkdir -p /mnt/nix/persist/
``` ```
### Secrets ### Secrets
All files in the Nix store are world-readable, so it is not a suitable place for including cleartext secrets, All files in the Nix store are world-readable, so it is not a suitable place
even if we had a scheme to securely transfer them to each system. [Agenix](https://github.com/ryantm/agenix) for including cleartext secrets, even if we had a scheme to securely transfer
solves this issue by encrypting the secrets using [age](https://github.com/FiloSottile/age), and then decrypting them to each system. [Agenix](https://github.com/ryantm/agenix) solves this
and symlinking them using the system's SSH host key during system activation. issue by encrypting the secrets using
[age](https://github.com/FiloSottile/age), and then decrypting and symlinking
them using the system's SSH host key during system activation.
All secrets, and other private configuration such as DNS zonefiles, are stored All secrets, and other private configuration such as DNS zonefiles, are stored
in a separate, private [repo](https://git.caspervk.net/caspervk/nixos-secrets). in a separate, private [repo](https://git.caspervk.net/caspervk/nixos-secrets).
To bootstrap a new system, we must first generate a host key manually using To bootstrap a new system, we must generate a host key manually during
`ssh-keygen -A -f /mnt/nix/persist` during installation. Then, on an existing installation:
system, add the new host's public key to `secrets.nix` in the `nixos-secrets` ```fish
repo and rekey all secrets using `agenix --rekey`. Commit and transfer the mkdir -p /mnt/nix/persist/etc/ssh/
repository to the new system. ssh-keygen -A -f /mnt/nix/persist
nc alpha.caspervk.net 1337 < /mnt/nix/persist/etc/ssh/ssh_host_ed25519.pub
When managing secrets, the Keepass recovery key is used like so: ```
Then, on an existing system, add the new host's public key to `secrets.nix` in
the `nixos-secrets` repo and **rekey** all secrets. When managing secrets, the
Keepass recovery key is used like so:
```fish ```fish
set AGE_KEY_FILE (mktemp); read -s > $AGE_KEY_FILE set AGE_KEY_FILE (mktemp); read -s > $AGE_KEY_FILE
agenix -i $AGE_KEY_FILE --rekey
agenix -i $AGE_KEY_FILE -e foo.age agenix -i $AGE_KEY_FILE -e foo.age
``` ```
The new system needs to be able to pull the `nixos-secrets` repo temporarily
during installation:
```fish
ssh-keygen -t ed25519
nc alpha.caspervk.net 1337 < /root/.ssh/id_ed25519.pub
# https://git.caspervk.net/caspervk/nixos-secrets/settings/keys
```
After bootstrapping, servers will auto-upgrade using the shared `autoUpgrade`
SSH key. Desktops will need to add `~caspervk/.ssh/id_ed25519.pub` either as a
deploy key for the `nixos-secrets` repo, or to the entire git user.
### Installation ### Installation
The remaining installation can be done (more or less) according to the [NixOS The remaining installation can be done (more or less) according to the [NixOS
manual](https://nixos.org/manual/nixos/stable/index.html#sec-installation-manual-installing). manual](https://nixos.org/manual/nixos/stable/index.html#sec-installation-manual-installing).
```fish ```fish
cd /mnt/nix cd /mnt/nix
git clone https://git.caspervk.net/caspervk/nixos.git tmp git clone https://git.caspervk.net/caspervk/nixos.git
cd tmp/ cd nixos/
nixos-generate-config --root /mnt --show-hardware-config nixos-generate-config --root /mnt --show-hardware-config
vim hosts/omega/hardware.nix vim hosts/omega/hardware.nix
git add . # nix sometimes ignores files outside version control git add . # nix sometimes ignores files outside version control
nixos-install --no-root-passwd --flake .#omega --override-input secrets ./../nixos-secrets/ nixos-install --no-root-passwd --flake .#omega
``` ```
### Hardware Configuration ### Hardware Configuration
`hosts/*/hardware.nix`, while initially generated by `nixos-generate-config --show-hardware-config`, _is_ manually `hosts/*/hardware.nix`, while initially generated by `nixos-generate-config
modified. --show-hardware-config`, _is_ manually modified.
### State Version ### State Version
Nixpkgs uses `stateVersion` so sparingly that auditing the entire nixpkgs repo is [easy Nixpkgs uses `stateVersion` so sparingly that auditing the entire nixpkgs repo
is [easy
enough](https://sourcegraph.com/search?q=context%3Aglobal+repo%3A%5Egithub%5C.com%3FNixOS%2Fnixpkgs%24++lang%3ANix+stateVersion+AND+23.11). enough](https://sourcegraph.com/search?q=context%3Aglobal+repo%3A%5Egithub%5C.com%3FNixOS%2Fnixpkgs%24++lang%3ANix+stateVersion+AND+23.11).