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Ubuntu VM Management

Introduction​

Virtual machines (VMs) provide a powerful way to run multiple operating systems simultaneously on a single physical computer. Ubuntu VM management involves creating, configuring, monitoring, and maintaining Ubuntu virtual machines. This guide focuses on managing Ubuntu VMs, whether Ubuntu is serving as the host system, the guest system, or both.

Virtualization offers several benefits:

  • Resource isolation: Run multiple environments without interference
  • Testing environment: Safe experimentation without affecting physical systems
  • Development flexibility: Create identical environments across different machines
  • Server consolidation: Optimize hardware usage by running multiple servers on one physical machine
  • Snapshot and backup: Easily create point-in-time backups of entire systems

Understanding Virtualization Types​

Before diving into Ubuntu VM management, it's important to understand different virtualization approaches:

  • Type 1 Hypervisors (bare-metal): Run directly on hardware
    • Examples: KVM, Xen
  • Type 2 Hypervisors (hosted): Run on top of an operating system
    • Examples: VirtualBox, VMware Workstation/Player, QEMU

This guide will focus on the most common tools for Ubuntu environments: KVM, VirtualBox, and Multipass.

Setting Up KVM on Ubuntu​

KVM (Kernel-based Virtual Machine) is integrated into Linux, making it powerful and efficient for running VMs on Ubuntu.

Prerequisites​

First, check if your hardware supports virtualization:

egrep -c '(vmx|svm)' /proc/cpuinfo

If the result is greater than 0, your CPU supports virtualization. Next, install the required packages:

sudo apt update
sudo apt install qemu-kvm libvirt-daemon-system libvirt-clients bridge-utils virt-manager

Configuring User Permissions​

Add your user to the necessary groups:

sudo adduser $USER libvirt
sudo adduser $USER kvm

Log out and log back in for the changes to take effect.

Creating an Ubuntu VM with virt-manager​

Virt-manager provides a graphical interface for VM management:

  1. Start virt-manager:

    sudo virt-manager

  2. Click "Create a new virtual machine"

  3. Select "Local install media" and click Forward

  4. Browse and select your Ubuntu ISO file or enter its location

  5. Allocate RAM and CPU resources

  6. Configure storage for the VM

  7. Configure network settings

  8. Complete the setup and start the VM

Managing VMs with KVM Command Line​

While virt-manager is convenient, command-line tools offer more control and scriptability.

Creating a VM with virsh​

sudo virt-install \
  --name ubuntu20.04 \
  --ram 2048 \
  --disk path=/var/lib/libvirt/images/ubuntu20.04.qcow2,size=20 \
  --vcpus 2 \
  --os-type linux \
  --os-variant ubuntu20.04 \
  --network bridge=virbr0 \
  --graphics none \
  --console pty,target_type=serial \
  --location 'http://archive.ubuntu.com/ubuntu/dists/focal/main/installer-amd64/' \
  --extra-args 'console=ttyS0,115200n8 serial'

Basic VM Management Commands​

List all VMs:

sudo virsh list --all

Start a VM:

sudo virsh start ubuntu20.04

Connect to the VM console:

sudo virsh console ubuntu20.04

Shutdown a VM gracefully:

sudo virsh shutdown ubuntu20.04

Force shutdown (like unplugging the power):

sudo virsh destroy ubuntu20.04

Delete a VM (caution: this removes the VM definition but not its storage):

sudo virsh undefine ubuntu20.04

To delete a VM and its storage:

sudo virsh undefine ubuntu20.04 --remove-all-storage

VM Snapshots with KVM​

Snapshots allow you to save the state of a VM at a point in time:

Create a snapshot:

sudo virsh snapshot-create-as ubuntu20.04 snapshot1 "Clean install with updates" --disk-only --atomic

List snapshots:

sudo virsh snapshot-list ubuntu20.04

Restore to a snapshot:

sudo virsh snapshot-revert ubuntu20.04 snapshot1

Delete a snapshot:

sudo virsh snapshot-delete ubuntu20.04 snapshot1

Using VirtualBox for Ubuntu VMs​

VirtualBox is a popular Type 2 hypervisor that's easy to use, making it ideal for beginners.

Installation​

sudo apt update
sudo apt install virtualbox

For enhanced functionality, install the extension pack:

sudo apt install virtualbox-ext-pack

Creating an Ubuntu VM in VirtualBox​

  1. Launch VirtualBox and click "New"
  2. Name your VM, select "Linux" as the type and "Ubuntu (64-bit)" as the version
  3. Allocate memory (at least 2GB recommended)
  4. Create a virtual hard disk
  5. Specify the Ubuntu ISO location
  6. Complete the setup and start the VM

VirtualBox Command Line Management​

VirtualBox also offers command-line tools for automation:

List VMs:

VBoxManage list vms

Create a VM:

VBoxManage createvm --name "UbuntuServer" --ostype Ubuntu_64 --register
VBoxManage modifyvm "UbuntuServer" --memory 2048 --cpus 2
VBoxManage createhd --filename ~/VirtualBox\ VMs/UbuntuServer/UbuntuServer.vdi --size 20000

Start a VM:

VBoxManage startvm "UbuntuServer"

Start a VM in headless mode (no GUI):

VBoxManage startvm "UbuntuServer" --type headless

Power off a VM:

VBoxManage controlvm "UbuntuServer" poweroff

VirtualBox Snapshots​

Create a snapshot:

VBoxManage snapshot "UbuntuServer" take "fresh-install" --description "Fresh Ubuntu installation"

List snapshots:

VBoxManage snapshot "UbuntuServer" list

Restore a snapshot:

VBoxManage snapshot "UbuntuServer" restore "fresh-install"

Multipass for Quick Ubuntu VMs​

Multipass, developed by Canonical, makes it extremely easy to spin up Ubuntu VMs for development and testing.

Installation​

sudo snap install multipass

Basic Multipass Commands​

Create a new Ubuntu VM:

multipass launch --name ubuntu-vm

List running instances:

multipass list

Execute commands in a VM:

multipass exec ubuntu-vm -- lsb_release -a

Open a shell in a VM:

multipass shell ubuntu-vm

Stop and start VMs:

multipass stop ubuntu-vm
multipass start ubuntu-vm

Delete a VM:

multipass delete ubuntu-vm
multipass purge  # Actually removes deleted VMs

VM Resource Management​

Efficiently managing VM resources is crucial for optimal performance.

Monitoring VM Performance​

Using KVM/QEMU:

sudo apt install virt-top
sudo virt-top

Or get detailed info:

sudo virsh dominfo ubuntu20.04

Adjusting VM Resources​

With KVM, modify VM settings (must be stopped first):

sudo virsh shutdown ubuntu20.04
sudo virsh setmaxmem ubuntu20.04 4G --config
sudo virsh setmem ubuntu20.04 4G --config
sudo virsh setvcpus ubuntu20.04 4 --config
sudo virsh start ubuntu20.04

With VirtualBox:

VBoxManage modifyvm "UbuntuServer" --memory 4096 --cpus 4

Networking Options for Ubuntu VMs​

VMs can connect to networks in different ways:

KVM Networking Modes​

Configure bridged networking with KVM:

sudo apt install bridge-utils
sudo nano /etc/netplan/01-netcfg.yaml

Add configuration like:

network:
  version: 2
  renderer: networkd
  ethernets:
    enp0s25:
      dhcp4: no
  bridges:
    br0:
      interfaces: [enp0s25]
      dhcp4: yes

Apply configuration:

sudo netplan apply

Update VM to use bridge:

sudo virsh edit ubuntu20.04

Change the network interface to:

<interface type='bridge'>
  <source bridge='br0'/>
  <model type='virtio'/>
</interface>

VirtualBox Networking​

In VirtualBox, the networking modes are:

  • NAT (default)
  • Bridged
  • Host-only
  • Internal network

To configure bridged networking from the command line:

VBoxManage modifyvm "UbuntuServer" --nic1 bridged --bridgeadapter1 enp0s25

Automating VM Management​

Creating VM Templates​

With KVM:

  1. Create a base VM with desired configurations
  2. Install all necessary packages
  3. Clean up the system
  4. Shut down the VM
  5. Create a template:
sudo virt-clone --original ubuntu20.04 --name ubuntu-template --file /var/lib/libvirt/images/ubuntu-template.qcow2

Using Cloud-Init with KVM​

For automated installations:

  1. Install required packages:
sudo apt install cloud-image-utils
  1. Download Ubuntu cloud image:
wget https://cloud-images.ubuntu.com/focal/current/focal-server-cloudimg-amd64.img
  1. Create a cloud-init configuration file cloud-config.yml:
#cloud-config
hostname: ubuntuvm
users:
  - name: ubuntu
    sudo: ALL=(ALL) NOPASSWD:ALL
    shell: /bin/bash
    ssh_authorized_keys:
      - ssh-rsa AAAA... your_key
password: ubuntu
chpasswd: { expire: False }
ssh_pwauth: True
  1. Create a disk with the configuration:
cloud-localds cloud-config.iso cloud-config.yml
  1. Create and start the VM:
sudo virt-install \
  --name ubuntu-cloud \
  --ram 2048 \
  --vcpus 2 \
  --disk focal-server-cloudimg-amd64.img,size=10 \
  --disk cloud-config.iso,device=cdrom \
  --os-type linux \
  --os-variant ubuntu20.04 \
  --network bridge=virbr0 \
  --graphics none \
  --import

Scripting VM Creation​

Create a bash script for automated VM deployment:

#!/bin/bash
# create_ubuntu_vm.sh

VM_NAME=$1
RAM=$2
CPUS=$3
DISK_SIZE=$4

if [ -z "$VM_NAME" ] || [ -z "$RAM" ] || [ -z "$CPUS" ] || [ -z "$DISK_SIZE" ]; then
  echo "Usage: $0 <vm_name> <ram_in_mb> <cpus> <disk_size_in_gb>"
  exit 1
fi

# Download Ubuntu cloud image if not present
IMAGE="focal-server-cloudimg-amd64.img"
if [ ! -f "$IMAGE" ]; then
  wget https://cloud-images.ubuntu.com/focal/current/$IMAGE
fi

# Create a copy of the image
cp $IMAGE $VM_NAME.img
qemu-img resize $VM_NAME.img ${DISK_SIZE}G

# Create cloud-init config
cat > cloud-config.yml <<EOF
#cloud-config
hostname: $VM_NAME
users:
  - name: ubuntu
    sudo: ALL=(ALL) NOPASSWD:ALL
    shell: /bin/bash
password: ubuntu
chpasswd: { expire: False }
ssh_pwauth: True
EOF

# Create cloud-init disk
cloud-localds $VM_NAME-cloud-config.iso cloud-config.yml

# Create and start VM
sudo virt-install \
  --name $VM_NAME \
  --ram $RAM \
  --vcpus $CPUS \
  --disk $VM_NAME.img \
  --disk $VM_NAME-cloud-config.iso,device=cdrom \
  --os-type linux \
  --os-variant ubuntu20.04 \
  --network bridge=virbr0 \
  --graphics none \
  --import

echo "VM $VM_NAME created and started"

Make the script executable:

chmod +x create_ubuntu_vm.sh

Usage:

./create_ubuntu_vm.sh webserver 2048 2 10

Best Practices for Ubuntu VM Management​

  1. Regular backups: Use snapshots but don't rely on them exclusively

    sudo virsh dumpxml ubuntu20.04 > ubuntu20.04.xml
    sudo cp /var/lib/libvirt/images/ubuntu20.04.qcow2 /backup/

  2. Security considerations:

    • Keep both host and guest systems updated
    • Use minimal installations for guests
    • Isolate sensitive VMs on separate networks
    • Disable unnecessary services

  3. Performance optimization:

    • Use virtio drivers where possible
    • Allocate resources based on actual needs
    • Enable CPU passthrough for intensive workloads: 
      sudo virsh edit ubuntu20.04
      Add CPU configuration: 
      <cpu mode='host-passthrough'/>

  4. Documentation: Keep records of VM configurations and purposes

    sudo virsh dumpxml ubuntu20.04 > ~/vm-configs/ubuntu20.04-config.xml

Troubleshooting Common Issues​

VM Won't Start​

Check the error:

sudo virsh start ubuntu20.04 --verbose

Check system logs:

sudo journalctl -u libvirtd

Performance Issues​

Check VM resource usage:

sudo virt-top

Check I/O wait issues:

top
# Look for high %wa values

Improve disk performance with cache settings:

sudo virsh edit ubuntu20.04

Modify disk cache:

<disk type='file' device='disk'>
  <driver name='qemu' type='qcow2' cache='none'/>
  ...
</disk>

Network Connectivity Issues​

Check the network interface status:

sudo virsh domiflist ubuntu20.04

Ensure the bridge is up:

ip a show virbr0

Verify firewall rules aren't blocking traffic:

sudo iptables -L -v | grep virbr0

Summary​

Ubuntu VM management offers powerful capabilities for creating flexible, isolated environments for development, testing, and production. We've covered:

  • Setting up virtualization environments with KVM, VirtualBox, and Multipass
  • Managing VMs through both graphical and command-line interfaces
  • Creating and restoring snapshots
  • Automating VM deployment with scripts and cloud-init
  • Configuring networking for different use cases
  • Optimizing performance and troubleshooting common issues

Additional Resources​

  1. Official Documentation:

  2. Practice Exercises:

    • Create a three-tier application using separate VMs for web, application, and database servers
    • Set up a development environment with automated deployment using cloud-init
    • Create a VM template and deploy multiple instances with different configurations

  3. Advanced Topics to Explore:

    • Container technologies (Docker, LXD) and how they compare to VMs
    • Orchestration tools for managing multiple VMs
    • Live migration between physical hosts
    • Nested virtualization

With these tools and techniques, you can effectively manage Ubuntu virtual machines for almost any use case, from simple development environments to complex multi-server deployments.


If you spot any mistakes on this website, please let me know at [email protected]. I’d greatly appreciate your feedback! :)