libvirt-notes/README.md

# libvirt/virt-install

## Prerequisites

`libvirt`, `qemu`, `virt-install`

### Archlinux:

```bash
pacman -S virt-install libvirt qemu-desktop
pacman -S virt-manager # optional, graphical interface to libvirt
pacman -S qemu-emulators-full # optional, provides extra architectures emulation for qemu

systemctl enable libvirtd.socket # socket activation
```

### MacOS

```bash
brew install qemu libvirt virt-manager # installing virt-manager might take a while since it requires GTK
# optional
brew install virt-viewer
brew services start libvirt
```

The procedure for installing VMs on MacOS is similar to the standard processes, although some flags have to be changed when running on M1:

1. remove the `--virt-type kvm` flag as this is not supported, it will fallback to `qemu` hypervisor
2. remove the `--cpu host` flag and  add `--arch x86_64` to `virt-install` in order to run an `x86_64` system (this might depends on the architecture you want to emulate)

Follow instructions below, editing commands as required.


## Installing VMs

### Archlinux

```bash
curl -O "https://mirror.checkdomain.de/archlinux/iso/2022.05.01/archlinux-2022.05.01-x86_64.iso"
virt-install --name archlinux                        \
            --memory 2048                            \
            --vcpus=2,maxvcpus=4 --cpu host          \
            --cdrom archlinux-2022.05.01-x86_64.iso  \
            --disk size=4,format=qcow2               \
            --network user                           \
            --virt-type kvm                          \
            --console pty,target_type=virtio         \
            --nographics
```

Follow the installation procedure. Edit the kernel cmdline and a serial console before rebooting otherwise the `virsh` serial console won't work:

In `/etc/default/grub`, add to the following to `GRUB_CMDLINE_LINUX` along with any other cmdline flags you require

```
GRUB_CMDLINE_LINUX=console=tty0 console=ttyS0,115200 # and any other flags
```

Update grub:

```bash
grub-mkconfig -o /boot/grub/grub.cfg
```

### Nixos

```bash
curl -O "https://channels.nixos.org/nixos-21.11/latest-nixos-minimal-x86_64-linux.iso"
virt-install --name nixos                                   \
            --memory 2048                                   \
            --vcpus=2,maxvcpus=4                            \
            --cpu host                                      \
            --cdrom latest-nixos-minimal-x86_64-linux.iso   \
            --disk size=4,format=qcow2                      \
            --network user                                  \
            --virt-type kvm                                 \
            --console pty,target_type=virtio                \
            --nographics
```

Follow the installation procedure, adding the following to `/etc/nixos/configuration.nix`, otherwise the `virsh` serial console won't work

```
boot.kernelParams = [
    "console=ttyS0,115200"
    "console=tty1"
  ];
```

### Ubuntu 21.10 (focal)

```bash
virt-install --name ubuntu-focal              \
             --memory 2048                    \
             --vcpus=2,maxvcpus=4             \
             --cpu host                       \
             --pxe                            \
             --disk size=4,format=qcow2       \
             --network user                   \
             --virt-type kvm                  \
             --nographics                     \
             --osinfo ubuntufocal             \
             --extra-args="console=tty0 console=ttyS0,115200" \
             --location http://archive.ubuntu.com/ubuntu/dists/focal/main/installer-amd64/
```

## Other OSs

You can list other supported Operating Systems using

```bash
virt-install --osinfo list
# More info about available OSs
osinfo-query os
```

### Note about serial consoles

In order for the virsh serial console to work, these kernel cmdline options have to be provided

```
console=tty0 console=ttyS0,115200
```

## Usage

```bash
# list all available domains (running and stopped)
virsh list --all
# Start a domain ("archlinux")
virsh start archlinux
# Connect to the serial console
virsh console archlinux
# Destroy (destop) a domain ("archlinux")
virsh destroy archlinux
# Remove a domain
virsh undefine archlinux # disks will **not** be removed
# Edit a domain
virsh edit archlinux
# Get information about network configuration
virsh domifaddr archlinux
```

### Note about serial consoles

Serial consoles might not work out of the box, so it might be required to edit the domain definition to add a serial console:

```bash
virsh edit <domain>
```

then add a pty console:

```xml
<console type='pty'>
  <target type='virtio' port='0'/>
</console>
```

Also see notes about serial consoles above.