How to Create an OS Template in Virtualizor: Complete Guide 2025

By HelpSysAdminLinux, server management
template virtualizor

Introduction

Creating custom OS templates in Virtualizor is essential for administrators who want to standardize virtual environments and streamline the provisioning process. This detailed guide will show you how to create professional and efficient OS templates in Virtualizor.

What is an OS Template in Virtualizor?

An OS (Operating System) template in Virtualizor is a preconfigured image that serves as the basis for creating new virtual machines (VMs) or VPS containers. These templates significantly speed up deployment and ensure consistency across servers.

Prerequisites

Before you start creating templates in Virtualizor, you’ll need:

  • Root access to the Virtualizor dashboard
  • Server with KVM, OpenVZ, Xen, or LXC virtualization configured
  • Base operating system installed and configured
  • Sufficient disk space to store the templates
  • Basic knowledge of Linux administration

Step by Step: Creating OS Templates in Virtualizor

Prepare the Base Virtual Machine

First, create and configure a VM with your desired operating system:

  • Install the OS cleanly (Ubuntu, CentOS, Debian, etc.)
  • Update all system packages
  • Configure only essential tools
  • Remove temporary files and logs
  • Clear the command history

Important tip: Keep the template as clean as possible to make future customizations easier.

2. Access the Virtualizor Panel

Access the Virtualizor admin panel:

  • Go to: https://your-server:4085
  • Log in with administrator credentials
  • Navigate to the “Templates” section in the side menu

3. Create Template from Existing VM

For technologies like KVM:

  • Completely shut down the VM that will be used as the base.
  • In the Virtualizor dashboard, go to Admin Panel > Templates.
  • Click Create Template.
  • Select the source VM.
  • Set a descriptive name for the template.
  • Add a detailed description.
  • Configure the file system (ext4, xfs, etc.).
  • Click Create to begin the process.

4. Create OpenVZ/LXC Template

For OpenVZ or LXC containers, the process is slightly different:

  • Prepare a configured base container
  • Stop the container: vzctl stop CTID
  • Create a tarball of the container
  • Move the file to the Virtualizor templates directory
  • Run the import command in Virtualizor
  • Update the templates list in the panel

5. Optimize the Template

Apply these optimizations to your template:

  • Reduce size: Remove unnecessary packages
  • Security: Configure a basic firewall and automatic updates
  • Performance: Adjust kernel parameters where applicable
  • Compatibility: Test on different virtual hardware configurations

6. Test the Template

Before using in production:

  • Create a new VM using the template
  • Verify that all services start correctly
  • Test network connectivity
  • Confirm that usernames and passwords are correct
  • Validate file and directory permissions

Best Practices for Templates in Virtualizor

Standardization

  • Use consistent naming conventions
  • Document all custom settings
  • Keep template versions organized
  • Create different templates for each specific purpose

Security

  • Disable unnecessary default accounts
  • Configure SSH with keys instead of passwords
  • Implement fail2ban or similar
  • Keep only essential services active

Maintenance

  • Update templates regularly (monthly or quarterly)
  • Keep a record of changes between versions
  • Test templates after each update
  • Archive old versions before replacing

Useful Commands for Managing Templates

bash

# List available templates
ls -lh /vz/template/cache/

# Check disk space for templates
df -h /vz/template/cache/

# Clear old template cache
rm /vz/template/cache/template-antigo.tar.gz

# Download official Virtualizor template
cd /vz/template/cache/ && wget URL-do-template

Troubleshooting Common Problems

Template does not appear in the list

  • Check template file permissions
  • Confirm it’s in the correct directory
  • Update the Virtualizor cache
  • Check logs in /var/log/virtualizor/

Error creating VM from template

  • Confirm available disk space
  • Check virtualization compatibility
  • Review the template’s network settings
  • Check specific logs for the created VM

Template too large

  • Remove accumulated log files
  • Clear package cache (apt/yum clean)
  • Uninstall unused packages
  • Consider additional compression

Recommended Templates for 2025

The most popular and trusted templates include:

  • Ubuntu 24.04 LTS: Stability and Long-Term Support
  • AlmaLinux 9: Enterprise CentOS Replacement
  • Debian 12: Lightweight and Proven Reliability
  • Rocky Linux 9: Excellent for Enterprise Environments

Automating Template Creation

For environments that need to create multiple templates, consider using automation scripts:

  1. Use tools like Packer to create automated templates.
  2. Implement CI/CD for template updates.
  3. Use Ansible or similar for post-installation configuration.
  4. Maintain Git repositories with configuration scripts.

Conclusion

Creating custom OS templates in Virtualizor is a fundamental process for administrators seeking efficiency and standardization. By following this guide, you’ll be able to create, manage, and optimize professional templates that meet the specific needs of your infrastructure.

Remember to keep your templates updated regularly and always test them before using them in production environments. With well-configured templates, you’ll significantly reduce provisioning time and minimize configuration errors.

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