Extending ARM Templates with Linked Templates | Azure ARM Tutorial

Welcome to the tutorial on extending ARM templates with linked templates in Azure Resource Manager (ARM). Linked templates provide a powerful way to modularize and scale your ARM deployments by breaking them into smaller, reusable components. In this tutorial, you will learn how to leverage linked templates to extend and enhance your ARM templates for more flexible and manageable deployments.

Introduction to Linked Templates

Linked templates allow you to divide your ARM deployments into multiple smaller templates, each responsible for deploying a specific set of resources or managing a particular aspect of your infrastructure. These templates can be linked together to form a hierarchical structure, enabling you to build complex deployments from reusable building blocks.

Using linked templates provides several benefits:

Modularity: Linked templates allow you to separate your deployments into smaller, manageable units, making it easier to maintain and update specific components without impacting the entire infrastructure.
Reusability: Linked templates can be reused across multiple deployments, promoting consistency and standardization across your infrastructure.
Scalability: By breaking your deployments into linked templates, you can scale your infrastructure by adding or removing specific components as needed.

Example of Using Linked Templates

Let's explore an example to understand how linked templates can be used:

1. Main Template

Create a main ARM template that acts as the entry point for your deployment. This template will reference and deploy one or more linked templates.


{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "resources": [
    {
      "type": "Microsoft.Resources/deployments",
      "apiVersion": "2021-04-01",
      "name": "linkedTemplateDeployment1",
      "properties": {
        "mode": "Incremental",
        "templateLink": {
          "uri": "[uri(deployment().properties.templateLink.uri, 'linkedTemplate1.json')]",
          "contentVersion": "1.0.0.0"
        }
      }
    },
    {
      "type": "Microsoft.Resources/deployments",
      "apiVersion": "2021-04-01",
      "name": "linkedTemplateDeployment2",
      "properties": {
        "mode": "Incremental",
        "templateLink": {
          "uri": "[uri(deployment().properties.templateLink.uri, 'linkedTemplate2.json')]",
          "contentVersion": "1.0.0.0"
        }
      }
    }
  ]
}

2. Linked Templates

Create separate linked templates, such as "linkedTemplate1.json" and "linkedTemplate2.json", that define the resources or configurations to be deployed. Each linked template can have its own parameters, variables, and resources.

Steps for Using Linked Templates

Follow these steps to extend your ARM templates with linked templates:

1. Create Linked Templates

Create separate ARM templates for each component or resource group that you want to deploy. These templates should be self-contained and define the resources and configurations specific to that component.

2. Reference Linked Templates in the Main Template

In your main ARM template, reference the linked templates by adding deployment resource blocks. Specify the URIs of the linked templates and set any required parameters.

3. Deploy the Main Template

Deploy the main ARM template as usual, either through the Azure portal, Azure CLI, Azure PowerShell, or any other deployment method you prefer. During the deployment process, the main template will deploy the linked templates and orchestrate the overall deployment.

Common Mistakes to Avoid

Not properly organizing and modularizing your ARM templates, leading to complex and hard-to-maintain deployments.
Forgetting to specify the correct URIs for the linked templates in the main template, resulting in deployment errors.
Not considering the dependencies and ordering of linked templates, causing resource deployment conflicts or inconsistencies.

Frequently Asked Questions (FAQs)

Q: Can I use linked templates across different resource groups or subscriptions?
A: Yes, linked templates can be used across different resource groups and even different subscriptions. You need to provide the appropriate URIs to the linked templates when referencing them in the main template.
Q: Can I pass parameters to the linked templates?
A: Yes, you can pass parameters to the linked templates by defining the necessary input parameters in both the main template and the linked templates.
Q: Can I link templates recursively?
A: Yes, you can link templates recursively, allowing you to create a hierarchy of linked templates for more complex deployments.
Q: How do I handle dependencies between linked templates?
A: You can handle dependencies between linked templates by ensuring that the templates are deployed in the correct order. You can use the "dependsOn" property to define dependencies between deployment resources in the main template.
Q: Can I use different deployment modes for linked templates?
A: Yes, you can specify different deployment modes, such as "Incremental" or "Complete," for each linked template deployment resource in the main template.

Summary

In this tutorial, you learned how to extend ARM templates with linked templates in Azure Resource Manager (ARM). By leveraging linked templates, you can modularize and scale your deployments, making them more manageable, reusable, and flexible. You now know how to create linked templates, reference them in the main template, and deploy the overall deployment. Avoid common mistakes and consider the provided FAQs to ensure smooth and efficient usage of linked templates. Start using linked templates to enhance the modularity and scalability of your ARM deployments and streamline your infrastructure provisioning process.