LXD 4.0 VMs: Specify disk size @ creation

LXD
1

Hello.

Is there a way to specify the disk size to create the LXD VM to? Currently, it sets to a default image of 9.3GB for an Ubuntu VM, but I need this to be larger, and I need to be able to configure it at creation time or otherwise expand it after launch.

Using the LXD 4.0 snap with a ZFS storage pool, and need to expand the disk space for the VM. How do I go about that?

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2

Nevermind, I figured this out.

I created a default ‘vm’ profile and have spinoff profiles from that with size definitions and growpart with cloud-init.

3

Could you expand on how exactly you did it?

How did you put VM disk size definitions into a profile?

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4

Heh, actually I got more info from the IRC channel heh.

Got a set of two commands - one to initialize the device and one to override disk size before starting. With a cloud-init setup using growpart it lets me spin Ubuntu VMs easily with LXD.

This is the ‘vm’ profile which controls deployment and base user/system config:

config:
  user.user-data: |
    #cloud-config
    ssh_pwauth: yes

    users:
      - name: teward
        passwd: "snip"  # Use a pw in /etc/shadow format!
        lock_passwd: false
        groups: lxd
        shell: /bin/bash
        sudo: ALL=(ALL) NOPASSWD:ALL

    growpart:
      mode: auto
      devices: ['/']
      ignore_growroot_disabled: false
description: LXD Profile for Virtual Machines
devices:
  config:
    source: cloud-init:config
    type: disk
  eth0:
    name: eth0
    nictype: bridged
    parent: lxdbr0
    type: nic
  root:
    path: /
    pool: lxd-qemu
    type: disk
name: vm

With this, the following two commands work (example using Ubuntu 18.04):

lxc init --vm ubuntu:18.04 bionic-vm --profile=vm
lxc config device override bionic-vm root size=50GB

(You can replace ‘50GB’ with any size that makes sense)

Or because VMs I deploy will need different sizes, I wrote this into a script which executes the relevant commands and prompts for the disk size (in GB), and uses the vm profile for init:

#!/bin/bash

if [ $(($#)) -lt 2 ]; then
    echo "Invalid number of arguments provided. Require: imagepath vmname"
    exit 1
fi

image=$1
name=$2

lxc init ${image} ${name} --vm --profile=vm
if [ $? -ne 0 ]; then
    echo "lxc init failed, please check output."
    exit 2;
fi

echo -n "Enter VM disk size in GB (min=20): "
read inputsize
size=$((inputsize))
if [ $((size)) -lt 20 ]; then
    echo "Size is smaller than 20GB, defaulting to 20GB."
    size=20
fi

lxc config device override ${name} root "size=${size}GB"
if [ $? -ne 0 ]; then
    echo "Unable to override VM disk size, please check error output."
    exit 3
fi

echo ""
echo "------"
echo ""
echo "LXD/QEMU-backed Virtual Machine ${name} created with disk of ${size}GB."
echo ""
echo "You may start your VM with:"
echo ""
echo "    lxc start ${name}"
echo ""
echo "...and access its console by using:"
echo ""
echo "    lxc console ${name}"
echo ""

… which when in the $PATH can be executed as lxc-launch-vm ubuntu:18.04 bionic-vm (where the first is the link to the image, and the second is the name - I only confirmed this works on Ubuntu VMs via LXD at the moment though…)

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