Create Azure Hub and Spoke model using ARM templates

The Hub and Spoke model is a popular Architecture for Teams who are migrating their Workloads to Cloud environment incrementally and still keep some workloads on-prem. Following are the main components that make-up Hub and Spoke model:

  1. Hub Virtual Network that holds your common components like VPN or Express Route Gateway, Azure Firewall, Azure Bastion Host etc. These components can be common to different environments like Dev, Staging, Prod etc. for better cost management.
  2. Spoke Virtual Network which have isolated workloads. These can hold VMs or other PaaS services like App Service that connect to On-Prem network via the Hub network gateway transit. There can be any number of Spokes.
Example Hub and Spoke Architecture

The benefits of hub and spoke configuration include cost savings, overcoming subscription limits and workload isolation.

Another example from the MS docs I found useful is as shown below:

I’m going to create the architecture shown above using ARM templates. You can find the templates for different components here. I’ve broken down the combined template into multiple templates that can be run in the following order by deploying them as Custom templates in Azure Portal and will be created in an existing Resource Group:

  1. Log Analytics workbook
  2. Hub (includes vpn gateway, firewall, bastion)
  3. Spoke1
  4. Spoke2
  5. Vnet Peerings
  6. Azure Sentinel
  7. Azure KeyVault

MS docs URL shared above contains more details about these components. Breaking down the templates into separate components gives you more control in creating a automated flow using say Azure pipelines. You can also later add or remove components easily as per your requirement.

Other options can be using Azure Blueprints for creating a minimal architecture and building from there on.

A similar architecture can created using Terraform as per MS docs here. But while running Terraform seems to be erroneous in Cloud shell and sometimes becomes unresponsive as per my experience.

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