docs: added README.md

README.md

@@ -1,2 +1,71 @@
-# nixos
+# Nixos Configuration
+
 Nixos Configuration Repository
+
+## Directories
+
+### `hardware-configuration`
+
+Contains the hardware configuration for each machine.
+
+### `profiles`
+
+Control plane for each machine. Each profile contains the configuration and features to be enabled for each machine.
+
+### `home`
+
+Contains the configuration/implementation at user level.
+As much as possible, configuration should be done in here to reduce surface of attack in the system, unless requiring system-wide access like `dbus` or `kernel modules`, or `root` needs access to the programs.
+
+### `options`
+
+Contains the options definition to toggle features in the system. Used by [profiles](#profiles) to enable or disable features.
+
+Options are meant to be shared between `system` and `home`. Hence, why the definitions are put in their own folder.
+
+### `secrets`
+
+Contains the secrets for the system. Uses [sops-nix] to encrypt the secrets.
+
+### `system`
+
+Contains system-wide configuration and implementation. Unless requiring system access, it's discouraged to put extended configurations here.
+Only parts that require system access allowed to be here.
+
+## Installation
+
+### Fresh Installation
+
+On new machine, copy this repo, copy the `hardware-configuration.nix` from `/etc/nixos/hardware-configuration.nix` to `./hardware-configuration/<hostname>.nix`.
+
+If creating new profile and hostname, create a new `<profile>.nix` in `./profiles` and
+create a new `nixosConfiguration.<hostname>` option in [`flake.nix`](./flake.nix) and
+re-target the `profile-path` and `hardware-configuration` variable (`specialArgs`) to the new files.
+
+Mount the root drive to `/mnt`, then run the following command:
+
+```sh
+nixos-install --flake /path/to/repository#<hostname>
+```
+
+### Reinstall
+
+If fresh from installation disk, Mount the target disk to `/mnt` and run the following command (Only on reinstalls):
+
+```sh
+nixos-install --flake https://github.com/tigorlazuardi/nixos#<hostname>
+
+# There are 2 hostnames available in this repo: 'castle' or 'fort'
+```
+
+## From Existing Installation
+
+Same steps as [Fresh Installation](#fresh-installation), but no need to mount the root drive.
+
+Then run the following command:
+
+```sh
+sudo nixos-rebuild switch --flake /path/to/repository#<hostname>
+```
+
+[sops-nix]: https://github.com/Mic92/sops-nix