Getting Started with ARM Templates in Azure

April 5th, 2023 Azure

Getting Started with ARM Templates in Azure

Azure Resource Manager (ARM) Templates are a powerful tool for managing and deploying infrastructure resources within Microsoft Azure. These templates are written in JSON and allow you to define, configure, and automate the deployment of Azure resources in a consistent and repeatable manner.

Getting started with ARM templates, including creating a basic template, deploying resources, and using template functions.

Understanding ARM Templates

ARM templates are JSON files that define the resources and their configurations in an Azure deployment. These templates can include parameters, variables, and outputs to make them reusable and customizable. The primary components of an ARM template are:

Resources: Azure services that are created and configured within the template.
Parameters: Values that can be passed into the template during deployment to customize the resources.
Variables: Named values that simplify the template by reducing redundancy and making it more maintainable.
Outputs: Values that are returned after a successful deployment, which can be used by other templates or tools.

Setting up your environment

Before you start creating ARM templates, you'll need to install the Azure CLI and the Azure PowerShell module on your machine. You can download and install them using the following links:

Azure CLI: https://docs.microsoft.com/en-us/cli/azure/install-azure-cli
Azure PowerShell: https://learn.microsoft.com/en-us/powershell/azure/install-az-ps

Creating a basic ARM Template

Let's create a simple ARM template to deploy a storage account. Save the following JSON code as a file named azuredeploy.json:

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "storageAccountName": {
      "type": "string",
      "metadata": {
        "description": "The name of the storage account."
      }
    }
  },
  "resources": [
    {
      "type": "Microsoft.Storage/storageAccounts",
      "apiVersion": "2021-04-01",
      "name": "[parameters('storageAccountName')]",
      "location": "[resourceGroup().location]",
      "sku": {
        "name": "Standard_LRS"
      },
      "kind": "StorageV2"
    }
  ]
}

In this template, we have defined a single parameter storageAccountName and used it to create a storage account resource.

Deploying resources using an ARM Template

To deploy resources using the ARM template, you can use either the Azure CLI or Azure PowerShell.

Using Azure CLI:

az group create --name myResourceGroup --location eastus

az deployment group create --resource-group myResourceGroup --template-file ./azuredeploy.json --parameters storageAccountName=myStorageAccount

Using Azure PowerShell:

New-AzResourceGroup -Name myResourceGroup -Location EastUS

New-AzResourceGroupDeployment -ResourceGroupName myResourceGroup -TemplateFile ./azuredeploy.json -storageAccountName myStorageAccount

These commands will create a new resource group named "myResourceGroup" in the "East US" region and deploy the storage account using the ARM template.

Exploring template functions

ARM templates include various functions that can be used to manipulate and transform data during deployment. Some common functions are:

concat(): Combines multiple strings into a single string.
uniqueString(): Generates a deterministic hash based on the input values.
resourceGroup(): Returns an object with properties of the resource group.
parameters(): Retrieves the value of a parameter.
variables(): Retrieves the value of a variable.

Here's an example of using the concat() and uniqueString() functions to generate a unique storage account name:

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "variables": {
    "storageAccountPrefix": "mystorage",
    "uniqueSuffix": "[uniqueString(resourceGroup().id)]"
  },
  "resources": [
    {
      "type": "Microsoft.Storage/storageAccounts",
      "apiVersion": "2021-04-01",
      "name": "[concat(variables('storageAccountPrefix'), variables('uniqueSuffix'))]",
      "location": "[resourceGroup().location]",
      "sku": {
        "name": "Standard_LRS"
      },
      "kind": "StorageV2"
    }
  ]
}

In this example, we've used the concat() function to combine the storageAccountPrefix variable and the uniqueSuffix variable, which is generated using the uniqueString() function. This creates a unique storage account name based on the resource group ID.

Conclusion

ARM templates provide a powerful and flexible way to manage and deploy Azure resources. By using these templates, you can ensure that your infrastructure deployments are consistent, repeatable, and maintainable.