Working with Nested Templates | Azure ARM Tutorial

Welcome to the tutorial on working with nested templates in ARM templates for Azure Resource Manager. ARM templates provide a powerful way to define and deploy infrastructure and applications in Azure. Nested templates allow you to break down complex deployments into smaller, reusable components, making your deployments more modular and manageable.

1. Using Nested Templates

Nested templates enable you to reference and deploy separate ARM templates within your main template. This allows you to divide your deployment logic into smaller, more manageable pieces.


"resources": [
  {
    "type": "Microsoft.Resources/deployments",
    "apiVersion": "2021-04-01",
    "name": "nestedDeployment",
    "properties": {
      "mode": "Incremental",
      "template": {
        "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
        "contentVersion": "1.0.0.0",
        "resources": [
          {
            "type": "Microsoft.Storage/storageAccounts",
            "name": "myStorageAccount",
            "apiVersion": "2021-04-01",
            ...
          }
        ]
      }
    }
  }
]

2. Working with Nested Templates

To work with nested templates effectively, follow these steps:

Step 1: Create Nested Template

Create a separate ARM template that contains the resources you want to deploy as a nested template. Save the nested template as a separate JSON file.

Step 2: Reference Nested Template

In your main ARM template, add a Microsoft.Resources/deployments resource to reference the nested template. Specify the URI or inline the nested template content within the template property.


"resources": [
  {
    "type": "Microsoft.Resources/deployments",
    "apiVersion": "2021-04-01",
    "name": "nestedDeployment",
    "properties": {
      "mode": "Incremental",
      "template": {
        "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
        "contentVersion": "1.0.0.0",
        "resources": [
          {
            "type": "Microsoft.Storage/storageAccounts",
            "name": "myStorageAccount",
            "apiVersion": "2021-04-01",
            ...
          }
        ]
      }
    }
  }
]

Step 3: Define Parameters and Variables

Define any required parameters and variables within the nested template. These parameters and variables can be referenced and passed values from the main template.


"resources": [
  {
    "type": "Microsoft.Storage/storageAccounts",
    "name": "[variables('storageAccountName')]",
    "apiVersion": "2021-04-01",
    ...
  }
]

Mistakes to Avoid

Not properly referencing the nested template within the main template.
Missing or incorrect usage of parameters and variables within the nested template.
Forgetting to provide the required values for parameters used in the nested template.

Frequently Asked Questions (FAQs)

Q: Can I nest templates within nested templates?
A: Yes, you can nest templates within nested templates to create a hierarchy of modular deployments. However, it's important to maintain proper organization and avoid excessive nesting.
Q: Can I pass values from the main template to the nested template?
A: Yes, you can pass values to the nested template by defining parameters in the nested template and providing values for those parameters in the main template.
Q: Can I reference resources created in the nested template from the main template?
A: Yes, resources created in the nested template can be referenced using the resource ID or by using the reference() function in the main template.
Q: Can I reuse the same nested template in multiple deployments?
A: Yes, nested templates are designed to be reusable. You can reference the same nested template in multiple deployments by specifying its URI or inline content within the main template.
Q: Can I conditionally deploy a nested template?
A: Yes, you can conditionally deploy a nested template by using the condition property in the main template. If the condition evaluates to false, the nested template will not be deployed.

Summary

In this tutorial, you learned how to work with nested templates in ARM templates for Azure Resource Manager. By dividing your deployments into smaller, reusable components, you can create more modular and manageable deployments. Nested templates allow you to reference and deploy separate ARM templates within your main template, making your deployments more organized and flexible.