= Installing btrfs, systemd-boot, and LUKS with suspend to disk on encrypted swap partition.

Ive been using archlinux for several years now.
Of course, my first installs were... blunderous, as i wanted to do full disk encryption from the get-go, and I didnt know what I was doing.
After those first one or two installs, I generally settled on LVM on LUKS with a GRUB bootloader and my swap on an LVM volume,
mostly because it makes it much easier to setup hibernation/suspend to disk vs, say, a swap file.
(with a swap file, you have to deal with file offsets, and I have never gotten a satisfactory awnser as to whether its possible for the filesystem to just *move* a file to a different disk sector in the process of, say, defragging with a very full hard drive.)

Anyway, with my newest laptop,
(I tend through them more than normal, as I buy them used off windows users once they become slow, but they are plenty fast for X11 less use or even light X11 use)
I decided to try out btrfs, in large part due to its snapshot system and ability to transfer those snapshots over a network.
(Im hoping to make a lightweight filesystem backup using this, on top of the data-level backups I currently use.)

However, suspend-to-disk is also quite important to me, and the archwiki is really only clear on how to do that with unencrypted partitions, LVM on LUKS, and on swapfiles.
The archwiki has some info on how to do it for the encrypt hook with a custom mkinitcpio hook, or with sd-encrytp hooks by just specifying multiple devices, but I didnt want to be writing a ton of custom config for the encrypt hook, and the section on sd-encrypt left some important quesions unawnsered.

////
I awnsered some of these questions:

//TODO: prettify this list.
- Does it matter if you use the kernel command line aurguments or /etc/crypttab.initramfs for suspend-to-disk support? no, but only use one or the other, not both.

- Does using /etc/crypttab.initramfs work when resuming from hibernate? yes.

- sd-encrypt caches your pw so that if multiple volumes can be unlocked with the same password, does that work with cryptab? yes.

- Is it safe to use the filesystem label when using /etc/cryptab.initramfs? yes. The filesystem label is persistent between boots and is stored in the FS header, along with the FS UUID you normaly use. It is exactly as persistent as the FS UUID.
////

== A note on security and risk profiles

TODO

== Things you should do first

Because some things are quite dependent on your system and network, as well as the type of system you end up with,
I will not be detailing some of the early setup steps, such as creating and booting from the arch ISO, or the final steps,
such as setting up a graphical environment.
Also, some of the middle steps require some modification depending on what sort of final setup you want, and your hardware.
I will call out those modifications in the relevant steps.

All this said, I would discorage you from blindly following this guide if its your first time installing arch (or a similarly diy distro like gentoo).
You should clearly understand what most of these commands do before typing them in.

Anyway, start by booting up the arch ISO...

== Installing via ssh

Sometimes, you dont want to be switching from the computer you are installing linux on and the computer wtih the documentatoin and google on it,
and Ive found the best way to avoid that is to set up a simple ssh session from the arch ISO to the computer with the documentation on it.

[IMPORTANT]
====
On a normal, already installed machine, *NEVER* use just a password for SSH. *ESPECIALLY* if it is internet-facing or connected to a public network. 
We are only doing this because we are (hopefully) on a personal network, and the password-based SSH session only exists on the Arch ISO, so as soon as you boot into your fresh system, the SSH session will be gone.
====

On the installee, make a password for the root account
....
# passwd
....

Enable SSH using

....
# systemctl start sshd.service
....

Find the ip adress with

....
# ip addr show
....

you are looking for a line like

....
inet 192.168.1.162/24 brd 192.168.1.255 scope global dynamic enp0s25
....

in this case, my LAN IP is 192.168.1.162

now, on the pc you are going to be SSHing from,

....
# ssh root@[ip we just found on installee]
....

and type in the password you set on the installee

now lets continue with the installation.

== inital setup

verify you are connected to the internet

....
# ping 1.1.1.1
....

turn on ntp

....
# timedatectl set-ntp true
....

== Partitioning

create paritions using the tools of your choice. I will be using the following partition map. If you use a different one, then 

an EFI partition of 512M

a swap partition with a size equal to your RAM.

a btrfs partition containing the rest of the space.

== Encryption

Encrypt the btrfs parition with

....
# cryptsetup luksFormat /dev/sda3

# cryptsetup config --label="btrfs" /dev/sda3
....

and enter the encryption passkey. I reccomend making it a full sentence for security.

Encrypt the swap partition. Use the same password as last time.

....
# cryptsetup luksFormat /dev/sda2

# cryptsetup config --label="swap" /dev/sda2
....

now open the newly encrypted partitions

....
# cryptsetup open /dev/sda2 swap

# cryptsetup open /dev/sda3 btrfs
....

== Filesystem creation

format the EFI poartion with FAT32 and give it the label EFI (label can be something else.)

....
# mkfs.vfat -F32 -n EFI /dev/sda1
....

format the swap partiton as swap

....
# mkswap /dev/mapper/swap
....

format the root partition with btrfs and give the label root (label can be something else.)

....
# mkfs.btrfs -L btrfs /dev/mapper/btrfs
....

== Creating and mounting subvolumes

....
# mount /dev/mapper/btrfs /mnt           

# btrfs subvolume create /mnt/root

# btrfs subvolume create /mnt/home

# umount /mnt
....

mount subvols and EFI partition

....
# mount -o noatime,nodiratime,compress=zstd,ssd,discard,subvol=root /dev/mapper/btrfs /mnt

# mkdir /mnt/home

# mount -o noatime,nodiratime,compress=zstd,ssd,discard,subvol=home /dev/mapper/btrfs /mnt/home

# mkdir /mnt/boot

# mount /dev/sda1 /mnt/boot

# swapon /dev/mapper/swap
....

== installing base system, generating *stab

install arch (ajust this to suit your needs), change intel-ucode to amd-ucode if using an AMD processor.

....
# pacstrap /mnt linux linux-firmware base base-devel btrfs-progs zsh neovim git stow tmux connman wpa_supplicant openvpn fzf htop rsync tig tree xdg-user-dirs units python tree openssh w3m curl intel-ucode
....

generate an fstab

....
# genfstab -U /mnt > /mnt/etc/fstab
....

make /mnt/etc/crypttab.initramfs containing:

....
#our swap device
swap LABEL=swap

#our main device
btrfs LABEL=btrfs
....

== system config

chroot into the new system

....
# arch-chroot /mnt/
....

set time zone.
 
 ....
# ln -sf /usr/share/zoneinfo/Region/City /etc/localtime
....

run hwclock

....
# hwclock --systohc
....

uncomment needed locales in /etc/locale.gen (you always need to at least uncomment en_US.UTF-8 UTF-8.)

gen locales

....
# locale-gen
....

set LANG variable

....
# echo 'LANG=en_US.UTF-8' > /etc/locale.conf
....

create the hostname file

....
# echo '[myhostname]' > /etc/hostname
....

and add maching entries to /etc/hosts, like so (if static ip, use that. if dynamic, use 127)

....
127.0.0.1	localhost
::1		localhost
127.0.1.1	myhostname.localdomain	myhostname
....

== installing the boot loader

edit /etc/mkinitcpio.conf so the HOOKS line looks like this:

....
HOOKS=(base systemd udev autodetect modconf block sd-encrypt btrfs resume filesystems keyboard fsck)
....

and regen the initramfs

....
# mkinitcpio -p linux
....

install systemd-boot

....
# bootctl install
....

create /boot/loader/entries/arch.conf containing:

....
title Arch Linux
linux /vmlinuz-linux
initrd /intel-ucode.img
initrd /initramfs-linux.img
options root=/dev/mapper/btrfs rootflags=subvol=/root resume=/dev/mapper/swap
....

edit /boot/loader/loader.conf and add:

....
default arch.conf
timeout 2
console-mode max
editor no
....

== system config

set root password

....
# passwd
....

exit and shutdown the system

....
# exit

# shutdown now
....

remove the install media, and boot back up. make sure everythign boots. from now on, configure the system as normal.

== configuring userspace

add a non-root user

....
# useradd -m -G wheel -s /bin/sh your_username
# passwd your_username
....

symlink neovim to vi (assuming you installed neovim but not vi. modify as your installed packages call for.)

....
# ln -s /usr/bin/nvim /usr/bin/vi
....

configure sudo

....
# visudo
....

uncomment the line that reads

....
%wheel ALL=(ALL) ALL
....

enable multilib: uncomment the following lines in /ec/pacman.conf

....
[multilib]
Include = /etc/pacman.d/mirrorlist
....

Congrats! you now have a barebones, but functional, encrypted arch install!
