blog/content/post/install-arch-linux-in-virtual-machine.md

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Install Arch Linux in Virtual Machine (KVM/QEMU)	2022-04-22T06:52:27Z	2022-05-07T06:52:27Z	false	kvm qemu arch vm "virtual machine" libvirt		libvirt	linux		false	true	false	true	false	false	false	false	false	false	false	enable options false	enable options false

Installing Arch Linux on a KVM/QEMU virtual machine is a fairly startightforward process. We will use command line approach in this post.

Create a virtual machine

Here we use virt-install to create a virtual machine. Run the following as root:

virt-install -n arch \
--os-type=linux \
--os-variant=archlinux \
--ram=2048 \
--vcpus=4 \
--disk path=/var/lib/libvirt/images/arch.qcow2,bus=virtio,size=32 \
--graphics=spice \
--cdrom /path/to/image.iso \
--network default

What is happening here?

• Here we specify name for the virtual machine, which is arch.
• Next we specify type and variant.
• The amount of RAM is specified in megabytes.
• We assign four virtual CPUs to the VM.
• In disk path we have given the default location where the virtual machine image is stored.
• Size is in gigabyes.
• We have used spice for graphics. Alternatively, VNC can be used.
• In cdrom we have provided the location of the boot media.
• Finally we asked virt-install to use the default network profile.

Pressing Enter will start the creation of the virtual machine. When done, it will start virt-viewer with live media running.

Install Arch Linux

This part is the same as any Arch Linux installation. We partition disks, run bootstrap script, generate locales, set timezone, hostname, install bootloader and optionally a desktop environment.

Partition disks

The virtual storage goes by /dev/sda. We partition disks using cfdisk. Select dos partition tabke since we are not using UEFI. Create just one partition and use it as root. Write then quit the program.

Now we format the partition.

mkfs.ext4 /dev/vda1

Mount root partition and install

Now we are ready to install Arch Linux. Mount root partition on /mnt with mount /dev/vda1 /mnt. Then we run the bootstrap script that will create the necessary files and install the specified packages.

pacstrap /mnt base base-devel linux vim dhcpcd

What is happening here?

• Here we asked pacstrap to install Arch Linux on /mnt.
• Then we specified the packages to be installed.
• The meta package base contains a minimal package set that defines a basic Arch Linux installation. It includes basic utilities like glibc, bash, coreutils, networking tools, systemd, etc.
• Next is the base-devel group. It contains tools to build many packages like gcc, make, binutils, etc.
• linux is the kernel.
• We require vim to configure various things. Any text editor will do.
• dhcpcd will allow us to connect to the internet. Alternatively, networkmanager can be used.

Generate fstab

This file tells which partitions to mount during boot. Instead of writing by hand, we use a tool to simplify things for us. Running the following

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

will generate a fstab file. We asked it to use /mnt partition. Any partition under /mnt will also be included, so if you created separate /home and /var partitions, they will also be included. The -U parameter tells genfstab to use UUID.

Configuration

In this section we set timezones, locale and hostname.

Chroot into new root

arch-chroot /mnt

Set timezone

List timezones by running timedatectl list-timezones. Set timezone with

timedatectl set-timezone Asia/Kolkata

Replace Asia/Kolkata with your timezone.

Set locale

Uncomment the desired locales in locale.gen

vim /etc/locale.gen

Save and exit then generate them by running

locale-gen

And set locale config

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

Replace en_US.UTF-8 with your locale.

Configure network

Set hostname

Your virtual machine will be identified by this name on the network

echo arch-vm > /etc/hostname

Create /etc/hosts

Your computer will look here for resolving domain names before looking out on the internet. Put the following information in /etc/hosts:

127.0.0.1   localhost
::1         localhost
127.0.1.1   arch-vm

Enable dhcpcd

This will enable the virtual machine to connect to the internet

systemctl enable dhcpcd.service

Create a user

Before we create a regular user, it becomes necessary to set a root password. Set it by running

passwd 

Create a new user with

useradd -m -G wheel,storage,power -s /bin/bash <username>

What is happening here?

• -m tells useradd ro create a home directory for this user.
• -G tells which groups this user will belong to.
• -s specifies the login shell for this user.
• Replace <username> with a username of your choice.

Set a password for this user with

passwd <username>

Install ssh server

If working on command line is all you have to do, then working via SSH is more convenient than using Spice client (or VNC if you chose that). Install it

pacman -S openssh

and enable it

systemctl enable sshd.service

Install bootloader

The instructions thus far will provide us a working bare minimum Arch Linux environment. Now it is time to install a bootloadet and finish the installation. We will go with grub.

pacman -S grub
grub-install /dev/vda
grub-mkconfig -o /boot/grub/grub.cfg

What is happening here?

• First we install grub package.
• Then we install it on the device /dev/vda.
• Next we create a configuration file. It can be modified at /etc/default/grub. Every time we modify the configuration, it must be generated with the last command for the changes to take place.

Reboot

The installation is complete. Next time we boot, we will be dropped into a working Ach Linux environment.

Exit chroot.

exit

Unmount partition

umoount /mnt 

And reboot

reboot

Connecting to the virtual machine

Wait for a minute and the virtual machine will be up. FInd the virtual machine's IP address on host machine (assuming arch is the name of your virtual machine)

virsh domifaddr arch

Save the IP address in your host's /etc/hosts

printf "<ip-address>\t<guest hostname>\n" | sudo tee -a /etc/hosts

Replace <ip-address> with the IP address of the virtual machine and <guest hostname> with the hostname you set while installing the virtual machine. It wuold be something like

printf "192.168.122.43\tarch-vm\n" | sudo tee -a /etc/hosts

Create SSH key pair

While not necessary on a local network, it is generally a good habit to use key pair instead of password authentication.

Go to ~/.ssh and create a key pair.

cd ~/.ssh 
ssh-keygen -t ed25519 -f arch-vm -C "arch linux virtual machine"

What is happening here?

• ssh-keygen generates keys.
• -t specifies the type of the key. We chose Ed25519. Other popular types are EdDSA, RSA, DSA, etc.
• -f specifies the filename of this key pair.
• -C is used to put comment in the key.

This process will ask for a passphrase and generates a private key and a public key. The public key will have extension .pub.

Create a config file. This will tell SSH which key to use with respect to host. The file is named config. Put the following in the file

Host arch-vm
  IdentityFile ~/.ssh/arch-vm

The private key is used to identify you. Anybody with your private key will be impersonate you so keep it safe.

Now copy the public key over to your virtual machine. It can be achieved by programs like scp or rsync. However, we will use ssh-copy-id to conveniently put our key while abstracting most parts.

ssh-copy-id -f -i ~/.ssh/arch arch@arch-vm

It is assuming arch is the username of the normal user of the virtual machine.

Now log in by running

ssh arch@arch-vm

Modify /etc/ssh/sshd_config to only use public key for authentication.

• Change PubkeyAuthentication to yes
• Change PasswordAuthentication to no
• Change X11Forwarding to yes

Now restart sshd for changes to take place.

systemctl restart sshd.config

Exit and try logging in again. This time it should ask for passphrase.

Install a desktop environment

This part is entirely optional if you wish to use GUI. In this post, we will install MATE desktop environment.

pacman -S mate mate-extra

The desktop environment can be started by running exec mate-session. If you want to use xinit then put the command in ~/.xinitrc. Then install xorg-xinit package. Start it with startx.

Alternatively you can use a display manager like GDM, LightDM, SDDM. etc. Install sddm, enable and start it

systemctl enable sddm.service
systemctl start sddm.service

If you wish to run GUI programs over X11 forwarding, a desktop environment might be overkill. In that case just install xorg, xorg-server. To use X11 forwarding, log in via ssh with

ssh -Y arch@arch-vm