Add nix files

nix/INSTALLATION.md

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+# INSTALLING ENCRYPTED NIX OS
+
+This is just a random jumbling of notes I took when I installed Nix on my T440s.
+
+## Partitioning
+
+I used the graphical installer and gparted to do partitioning.
+
+
+First, the partition table should be GPT.
+
+1MB grub data partition - EXT4 and bios_grub flag set. I called this partition "grub". Make sure to click "apply".
+Otherwise it will not let you right click -> manage flags to set `bios_grub` to true.
+
+1GB boot partition - on the large side but I have 500GB to spend. Set this to fat32. Flags are "boot" and "esp".
+
+Finally use the remaining space in one big partition, format it to EXT4 with the lvm flag, and commit it.
+
+## Disk Encryption
+
+The large LVM partition above is our encrypted partition.
+
+Type `cryptSetup luksFormat /dev/sdX3` where `sdX` is the drive name. Enter a good password. Not used anywhere
+else.
+
+Now we need to create the partitions
+
+`cryptsetup luksOpen /dev/sdX3 enc-pv` and enter the password from above.
+
+`pvcreate /dev/mapper/enc-pv` to initialize the partition.
+
+`vgcreate vg /dev/mapper/enc-pv` to create the volume group `vg` on `/dev/mapper/enc-pv` from above.
+
+`lvcreate -L 16GB -n swap vg` to create a swap logical volume on vg. I went with 2x RAM_SIZE_IN_GB. This is a little
+excessive and can be reduced quite a bit.
+
+`lvcreate -l 100%FREE -n root vg` to create the root logical volume on vg. This consumes the remaining space in the
+volume group.
+
+## Partition Formatting and Mounting
+
+Since we used `gparted` it is not necessary to format the unencrypted partitions.
+
+For `root` however we need to format it `ext4` (or whatever format you want) and also configure the swap.
+
+`mkfs.ext4 -0 dir_index -j -L root /dev/vg/root` to format the root as `ext4`.
+
+`mkswap -L swap /dev/vg/swap`.
+
+Now let's mount these for installation:
+
+`mount /dev/vg/root /mnt`
+`mkdir /mnt/boot`
+`mount /dev/sdX2 /mnt/boot`
+`swapon /dev/vg/swap`
+
+## Initial Nix Configuration
+
+Now we need to set up a barebones configuration so we can see if we can boot up.
+
+`nixos-generate-config --root /mnt`
+
+This will give us two files, `/etc/nixos/hardware-configuration.nix` and `/etc/nixos/configuration.nix` to set the
+system up with.
+
+The defaults are fairly sane for an initial boot. Double check to make sure everything looks okay according to
+your system specs.
+
+The major change we need to make is to let NixOS know we have an encrypted partition. Add the following into the
+`configuration.nix` file.
+
+```
+boot.initrd.luks.devices = [
+  { name = "root"; device = "/dev/sdX3"; preLVM = true; }
+];
+```
+
+I tend to keep my boot stuff grouped together near the top.
+
+We will keep the `gummiboot` related lines. `gummiboot` is a good enough bootloader for our purposes.
+
+In your `hardware-configuration.nix` file your boot partition may not have the right `fsType`. Change it to `vfat` if
+necessary.
+
+Finally, add `networking.wireless.enable = true;` to the file so we can use `wpa_supplicant` when we boot back up.
+
+now type `reboot` to reboot. You should see gummiboot.
+
+## Installing the Rest of the System
+
+Now that the hardest part is over we can configure Nix.
+
+Let's begin by setting up a user.
+
+`useradd -m <your_name>`
+`passwd <your_name>`
+`groupadd -a -G wheel <your_name>`
+
+This will grant your user access to everything under sudo.