Creating Headless Virtual Machines on a Headless Server

Introduction

Setting up virtual machines (VMs) on a headless server can be a powerful way to maximize your hardware resources and run multiple isolated environments. This guide will walk you through the process of creating and managing headless VMs on a headless server using libvirt and QEMU.

Initial Setup

When you first boot into your new virtual machine, you'll need to perform some initial configuration steps:

1. Log in to the correct subdomain
2. Verify network connectivity by pinging Google
3. Set up your terminal environment for better usability

Configuring the Terminal

To improve the terminal experience, add the following line to your .profile file:

export TERM=xterm

This will help with arrow key functionality and other terminal features.

Creating Bash Aliases

Create a .bash_aliases file and add useful aliases, such as:

alias ll='ls -lah --color=auto'

Remember to source your .bashrc file to apply the changes.

Mounting Host Directories

One of the most useful features when working with VMs is the ability to share directories between the host and guest systems. Here's how to mount a host directory in your VM:

1. Create a mount point in the VM:

   sudo mkdir /mount/scripts
   

2. Mount the host directory using the 9p filesystem:

   sudo mount -t 9p -o trans=virtio scripts /mount/scripts
   

3. Verify the mount by listing the contents of the directory:

   ls /mount/scripts
   

Automating the Mount Process

To ensure the directory is mounted automatically on boot, you can create a systemd service:

1. Create a script to perform the mount:

   vim ~/scripts/mount_fs.sh
   

   Add the following content:

   #!/bin/bash
   sudo mount -t 9p -o trans=virtio scripts /mount/scripts
   

2. Make the script executable:

   chmod +x ~/scripts/mount_fs.sh
   

3. Create a systemd service file:

   sudo vim /etc/systemd/system/mount_fs.service
   

   Add the following content:

   [Unit]
   Description=Mount external file systems
   
   [Service]
   Type=oneshot
   ExecStart=/home/username/scripts/mount_fs.sh
   
   [Install]
   WantedBy=multi-user.target
   

4. Enable and start the service:

   sudo systemctl enable mount_fs.service
   sudo systemctl start mount_fs.service
   

Managing Virtual Machines

Starting and Stopping VMs

To start a VM:

sudo virsh start vm_name

To stop a VM gracefully:

sudo virsh shutdown vm_name

To force stop a VM:

sudo virsh destroy vm_name

Accessing the VM Console

To access the console of a headless VM:

sudo virsh console vm_name

To exit the console, use the escape sequence: Ctrl + ]

Snapshots and Backups

Taking snapshots of your VMs is crucial for backup and recovery purposes. However, there are some limitations to be aware of:

UEFI vs Legacy Boot

Creating snapshots for UEFI-based VMs can be challenging. If possible, use legacy boot for your VMs to simplify the snapshot process.

To create a snapshot for a non-UEFI VM:

sudo virsh snapshot-create-as vm_name snapshot_name

For UEFI VMs, you may need to use external snapshots, which are more complex to manage.

Networking

Ensure your VM is configured to use the correct network interface. In this guide, we used a bridged network setup.

To verify network connectivity:

ping google.com

Troubleshooting

File Permissions

If you encounter permission issues when trying to access shared directories, you may need to adjust the ownership and permissions:

1. Change the ownership of the shared directory:

   sudo chown -R username:libvirt-qemu /path/to/shared/directory
   

2. Set appropriate permissions:

   sudo chmod -R 775 /path/to/shared/directory
   

VM Configuration

If you need to modify VM settings, you can edit the VM's XML configuration file:

sudo virsh edit vm_name

This will open the configuration in your default text editor. Be cautious when making changes, as incorrect modifications can render your VM unbootable.

Performance Considerations

Running VMs on a headless server can introduce some performance overhead, especially when dealing with multiple layers of virtualization. Keep this in mind when planning your VM workloads and resource allocation.

Security

When working with VMs, especially those with shared resources, it's important to consider security implications:

1. Use strong passwords for VM access
2. Keep your host and guest systems updated
3. Implement proper network segmentation
4. Use firewalls to control traffic between VMs and the host
5. Regularly audit your VM configurations and access logs

Conclusion

Creating and managing headless virtual machines on a headless server provides a flexible and powerful way to utilize your hardware resources. By following this guide, you should now have a solid understanding of how to set up, configure, and manage VMs in this environment.

Remember to regularly backup your VMs and keep your systems updated to ensure optimal performance and security. As you become more comfortable with this setup, you can explore advanced features like live migration, nested virtualization, and automated provisioning to further enhance your virtual infrastructure.

With practice and experience, you'll be able to create complex, multi-VM environments that can support a wide range of applications and services, all running efficiently on your headless server.

Article created from: https://www.youtube.com/watch?v=upJ-0jOqAEc