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VyOS High Availability (HA) Deployment on Azure
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This document describes how to deploy VyOS in a High Availability (HA) configuration on Azure using Terraform and Azure Route Server to provide sub-second failover.

Why Use HA on Azure?
--------------------

This module provides a robust, repeatable foundation for building **resilient network architectures** in Azure. By combining VyOS routing features with Terraform and Azure-native services, it enables:

- Rapid deployment of cloud edge routers.

- Full control over BGP route advertisement and filtering.

- Realistic HA and disaster recovery simulations.

- Seamless integration with hybrid or multi-cloud infrastructure.

The architecture includes:

- Two VyOS routers in a Transit VNet, configured with BGP.

- Azure Route Server for dynamic route distribution.

- Site-to-Site VPN connections to a simulated on-premises VyOS router.

- An Ubuntu VM for connectivity and routing validation.

- A Data VNet for testing and diagnostics.

Key Features
------------

- **High Availability**: Dual VyOS routers for redundancy and failover.

- **Dynamic Routing**: BGP-based routing via Azure Route Server.

- **Hybrid Connectivity**: Site-to-Site VPN integration with a simulated on-prem VyOS.

- **Testing Environment**: Includes Ubuntu VM for verification and diagnostics.

- **Modular & Flexible**: Easily configurable via variables.

HA Architecture Diagram
-----------------------

.. figure:: /_static/images/cloud-azure-ha-architecture.png
   :alt: VyOS HA topology diagram

This deployment architecture simulates a real-world enterprise network scenario for testing and validation purposes.

Terraform Automation
--------------------

To streamline and standardize the process, we developed a Terraform project that automates the deployment of VyOS in High Availability (HA) mode on Azure.

This Terraform project automates the deployment of:

- Two VyOS instances in HA mode.

- Azure Route Server.

- A Transit VNet and a Data VNet containing a test Ubuntu VM for connectivity validation.

Prerequisites
-------------

Ensure you have:

- Active Azure subscription:

.. code-block:: none

   az account set --subscription "<subscription ID or name>"

- Azure CLI installed:

  https://learn.microsoft.com/en-us/cli/azure/install-azure-cli

- Logged in with Azure credentials:

.. code-block:: none

   az version
   az login

- Azure Resource Group (RG) created:

.. code-block:: none

   az group create --name demoResourceGroup --location westus
   az group list
   az group show --name demoResourceGroup

- Terraform installed:

  https://developer.hashicorp.com/terraform/tutorials/aws-get-started/install-cli

- SSH key generated:

.. code-block:: none

   ssh-keygen -t rsa -b 4096 -f keys/vyos_custom_key.pem
   chmod 400 keys/vyos_custom_key.pem

Usage
-----

All variables are defined in ``variables.tf``. Adjust them to match your environment.

Terraform Workflow:

.. code-block:: none

  terraform init
  terraform fmt
  terraform validate
  terraform plan
  terraform apply

On completion, run:

.. code-block:: none

  terraform output

This displays the management IP and connectivity test results.

To clean up:

.. code-block:: none

  terraform destroy

Management
----------

SSH into VyOS:

.. code-block:: none

  ssh adminuser@<vyos_public_ip> -i keys/vyos_custom_key.pem


GitHub Repository
-----------------

You can clone or download the Terraform project and use them in your environment:

https://github.com/vyos/vyos-automation/tree/main/Terraform/Azure/azure-ha-deployment-with-configs