#ARM

Azure Resource Manager (ARM) Templates

Overview

Azure Resource Manager (ARM) templates are JSON files that declare the desired state of Azure infrastructure. Developers define resources and configurations, submit the template to ARM, and Azure provisions and configures everything automatically. This is declarative Infrastructure as Code.

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Introduction to ARM Templates

• Describe what to deploy, not how to deploy.
• Enable repeatable, idempotent deployments across environments.
• Support dependencies, parameterization, and outputs for modular, reusable infrastructure.

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How to Write ARM Templates

• Define parameters for environment-specific values.
• Add variables for computed names/strings.
• List resources with types, API versions, properties, and dependencies.
• Include outputs to return IDs, connection strings, etc.
• Validate and deploy via Azure CLI / PowerShell / Portal.

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Template Structure and Anatomy

• $schema: Template schema URL.
• contentVersion: Your version tag (e.g., 1.0.0.0).
• parameters: Inputs (names, types, defaults).
• variables: Derived values.
• functions: Built-in and user-defined template functions.
• resources: Array of resource declarations.
• outputs: Values returned after deployment.

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Core Properties and Uses

• $schema: Enables tooling validation.
• contentVersion: Controls versioning.
• parameters: e.g., location, names, sizes.
• variables: String concat, resource names.
• resources: type, apiVersion, name, location, properties, dependsOn.
• outputs: Expose resource data (IDs, endpoints).
• functions: concat, format, reference, resourceId, listKeys, if, copy loops.

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{
  "$schema": "",
  "contentVersion": "",
  "parameters": {},
  "variables": {},
  "functions": [],
  "resources": [],
  "outputs": {}
}

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Practical Examples

Storage Account

{
  "type": "Microsoft.Storage/storageAccounts",
  "apiVersion": "2023-01-01",
  "name": "[parameters('storageName')]",
  "location": "[parameters('location')]",
  "sku": { "name": "Standard_LRS" },
  "kind": "StorageV2"
}

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ARM template for storage account

{
    "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
    "contentVersion": "1.0.0.0",
    "parameters": {
        "dev-Type": {
            "type": "string",
            "defaultValue": "Standard_LRS",
            "allowedValues": [
                "Standard_LRS",
                "Standard_ZRS",
                "Standard_GRS",
                "Standard_RAGRS",
                "Premium_LRS"
            ]
        }
    },
    "resources": [
        {
            "name": "[variables('dev-Name')]",
            "type": "Microsoft.Storage/storageAccounts",
            "location": "[resourceGroup().location]",
            "apiVersion": "2015-06-15",
            "dependsOn": [],
            "tags": {
                "displayName": "dev-"
            },
            "properties": {
                "accountType": "[parameters('dev-Type')]"
            }
        }
    ],
    "variables": {
        "dev-Name": "[concat('dev-', uniqueString(resourceGroup().id))]"
    }
}