Graham Eddy

virtualbox using CLI

Create a simple linux virtual machine using CLI (suitable for headless server).

However, the VM instance has an emulated physical console accessed via RDP, if required.

2021-06-22 Ubuntu 21.10-22.04

Main characteristics of this implementation:

• Uses systemctl to start/stop VM instances. The various methods officially documented, including by virtualbox, to autostart VM instance when its host boots are impractical or don't work. This works.
• Assigns ownership of all VM instances to a system user vbox and all users of a VM instance belong to group vbox.

There can be many VM instances. The example VM has configuration:

VM name

goblin

CPUs

1 x shared

RAM

1 MB

NICs

1 – bridged to local LAN, not separate subnet

HDD

1 x 10 MB

DVD

1

Installation

• Answer Y to license prompt on virtualbox extras pack.
• This is a big install (about 180 MB) and includes lots of Gnome GUI, which is unfortunate as we have headless host.

Policy: keep VM resources under one roof:

# members of group 'vbox' permitted to run VBox commands as user 'vbox'
%vbox ALL = (vbox) NOPASSWD: \
    /usr/bin/VBoxManage, \
    /usr/bin/VBoxHeadless, \
    /usr/bin/VBoxSDL, \
    /usr/bin/VBoxBalloonCtrl

• Add all users who need access to a VM to group vbox.

# vm_instance - manage virtualbox VM instance

[Unit]
Description=VirtualBox VM %I
After=network.target virtualbox.service
Before=runlevel2.target shutdown.target

[Service]
User=vbox
Group=vbox
Type=forking
Restart=no
TimeoutSec=5min
IgnoreSIGPIPE=no
KillMode=process
GuessMainPID=no
RemainAfterExit=yes
ExecStart=/usr/bin/VBoxManage startvm %i --type headless
ExecStop=/usr/bin/VBoxManage controlvm %i acpipowerbutton

[Install]
WantedBy=multi-user.target

Create a VM instance

Add a NIC. Rather than creating a new private subnet with NAT, our VM instance will be just another host on our LAN, to which we have already assigned its own IP address. We will share the host's NIC and subnet.

Attach a new, bootable but empty 10GB virtual disk. We will store the virtual disk file in vbox's home directory virtualbox space.

Obtain an ISO file of OS install image (download from somewhere) and store it in vbox's home directory e.g. ~vbox/ubuntu-21.04-live-server-amd64.iso.

Attach a new DVD drive and mount the OS install image.

Enable RDP on VM instance to emulate physical console. Unless the OS install image is able to autoconfigure itself unattended e.g. ssh enabled and working – a practice only started recently – to complete installation of the OS inside a new VM instance, access to (emulated) physical consoles required i.e. an RDP client.

Inspect our creation:

Allow systemctl to manage this VM instance:

At this point the new VM instance is inert (not booted), no OS has been installed, but the install CD is loaded.

Start VM instance

• This starts the VM instance i.e. it begins to boot up. How long it takes to boot depends what is in the VM instance. You can check its readiness for ssh login by pinging it.

First boot special needs

If this is the VM instance's first boot, it is looking to install the OS from the already-mounted OS image:

• If set up for unattended install – unlikely unless it is a recent, custom image such as Raspbian bullseye – then allow 15-20 minutes for that to complete, then ssh should be available.
• If not unattended install, then you must use the (emulated) physical console (i.e. connect via RDP) to complete the installation. Make sure to enable OpenSSH when installing.

FYI, some problems encountered with Mac Mini as host running Ubuntu 21.10 when installing client OS:

• Selecting next OS version fails due to invalid shim under /boot → stay with version on install CD.
• De-selecting LVM results in crash during next step → leave LVM selected.
• Virtual CD not unmounted cleanly at end of install so it tries and fails to boot from it on restart → coerce boot from hard disk. Once-off problem per install.

Stop VM instance

• This initiates a clean shutdown. The systemctl command finishes immediately but the actual shutdown can take several minutes. You can monitor using ping.

Alternatively – not recommended normal practice! – you can directly just 'pull the plug' by: