Infrastructure as Code with ARM Templates and Bicep: Part 3 – Advanced ARM Template Patterns → Explore with me!

This entry is part 3 of 7 in the series Infrastructure as Code templates using ARM and Bicep

Infrastructure as Code templates using ARM and Bicep

Infrastructure as Code with ARM Templates and Bicep: Part 1 – ARM Template Fundamentals
Infrastructure as Code with ARM Templates and Bicep: Part 2 – Building Production-Ready Infrastructure
Infrastructure as Code with ARM Templates and Bicep: Part 3 – Advanced ARM Template Patterns
Infrastructure as Code with ARM Templates and Bicep: Part 4 – Introduction to Bicep
Infrastructure as Code with ARM Templates and Bicep: Part 5 – Advanced Bicep Patterns
Infrastructure as Code with ARM Templates and Bicep: Part 6 – CI/CD Integration and Advanced Deployment
Infrastructure as Code with ARM Templates and Bicep: Part 7 – Enterprise Governance and Compliance

As your infrastructure grows in complexity, you’ll need advanced ARM template patterns to maintain modularity, handle conditional deployments, and efficiently create multiple similar resources. This part covers nested templates, linked templates, conditional logic, and copy loops.

Welcome to Part 3 of our Infrastructure as Code series, where we explore the advanced patterns that make ARM templates truly powerful for enterprise scenarios.

What You’ll Learn

Nested and linked template patterns
Conditional resource deployment
Copy loops for arrays and objects
Template modularity and reusability
Advanced parameter handling

Template Modularity with Linked Templates

Break down complex infrastructure into manageable, reusable modules:

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "projectName": {
      "type": "string"
    },
    "environment": {
      "type": "string",
      "allowedValues": ["dev", "staging", "prod"]
    },
    "deployDatabase": {
      "type": "bool",
      "defaultValue": true
    },
    "vmCount": {
      "type": "int",
      "defaultValue": 1,
      "minValue": 1,
      "maxValue": 5
    },
    "_artifactsLocation": {
      "type": "string",
      "defaultValue": "[deployment().properties.templateLink.uri]"
    }
  },
  "variables": {
    "templateBaseUri": "[uri(parameters('_artifactsLocation'), '.')]",
    "networkTemplateUri": "[uri(variables('templateBaseUri'), 'modules/network.json')]",
    "storageTemplateUri": "[uri(variables('templateBaseUri'), 'modules/storage.json')]",
    "computeTemplateUri": "[uri(variables('templateBaseUri'), 'modules/compute.json')]",
    "databaseTemplateUri": "[uri(variables('templateBaseUri'), 'modules/database.json')]"
  },
  "resources": [
    {
      "type": "Microsoft.Resources/deployments",
      "apiVersion": "2021-04-01",
      "name": "networkDeployment",
      "properties": {
        "mode": "Incremental",
        "templateLink": {
          "uri": "[variables('networkTemplateUri')]"
        },
        "parameters": {
          "projectName": {
            "value": "[parameters('projectName')]"
          },
          "environment": {
            "value": "[parameters('environment')]"
          }
        }
      }
    },
    {
      "type": "Microsoft.Resources/deployments",
      "apiVersion": "2021-04-01",
      "name": "storageDeployment",
      "dependsOn": [
        "networkDeployment"
      ],
      "properties": {
        "mode": "Incremental",
        "templateLink": {
          "uri": "[variables('storageTemplateUri')]"
        },
        "parameters": {
          "projectName": {
            "value": "[parameters('projectName')]"
          },
          "environment": {
            "value": "[parameters('environment')]"
          },
          "vnetResourceId": {
            "value": "[reference('networkDeployment').outputs.vnetResourceId.value]"
          }
        }
      }
    },
    {
      "condition": "[parameters('deployDatabase')]",
      "type": "Microsoft.Resources/deployments",
      "apiVersion": "2021-04-01",
      "name": "databaseDeployment",
      "dependsOn": [
        "networkDeployment"
      ],
      "properties": {
        "mode": "Incremental",
        "templateLink": {
          "uri": "[variables('databaseTemplateUri')]"
        },
        "parameters": {
          "projectName": {
            "value": "[parameters('projectName')]"
          },
          "environment": {
            "value": "[parameters('environment')]"
          },
          "dataSubnetResourceId": {
            "value": "[reference('networkDeployment').outputs.dataSubnetResourceId.value]"
          }
        }
      }
    }
  ],
  "outputs": {
    "deploymentSummary": {
      "type": "object",
      "value": {
        "networkDeployed": true,
        "storageDeployed": true,
        "databaseDeployed": "[parameters('deployDatabase')]",
        "vmCount": "[parameters('vmCount')]"
      }
    }
  }
}

Copy Loops for Scaling Resources

Use copy loops to create multiple instances of resources efficiently:

{
  "type": "Microsoft.Network/networkInterfaces",
  "apiVersion": "2023-04-01",
  "name": "[concat('nic-vm', copyIndex(1), '-', parameters('projectName'), '-', parameters('environment'))]",
  "location": "[resourceGroup().location]",
  "copy": {
    "name": "nicLoop",
    "count": "[parameters('vmCount')]"
  },
  "dependsOn": [
    "[resourceId('Microsoft.Network/networkSecurityGroups', variables('networkSecurityGroupName'))]",
    "[resourceId('Microsoft.Network/loadBalancers', variables('loadBalancerName'))]"
  ],
  "properties": {
    "ipConfigurations": [
      {
        "name": "ipconfig1",
        "properties": {
          "privateIPAllocationMethod": "Dynamic",
          "subnet": {
            "id": "[parameters('subnetResourceId')]"
          },
          "loadBalancerBackendAddressPools": "[if(greater(parameters('vmCount'), 1), createArray(createObject('id', concat(resourceId('Microsoft.Network/loadBalancers', variables('loadBalancerName')), '/backendAddressPools/BackendPool1'))), createArray())]"
        }
      }
    ],
    "networkSecurityGroup": {
      "id": "[resourceId('Microsoft.Network/networkSecurityGroups', variables('networkSecurityGroupName'))]"
    }
  }
}

Advanced Variable Copy Patterns

Use variable copy for complex object construction:

"variables": {
  "copy": [
    {
      "name": "virtualMachines",
      "count": "[parameters('vmCount')]",
      "input": {
        "name": "[concat('vm', copyIndex('virtualMachines', 1))]",
        "size": "[if(equals(parameters('environment'), 'prod'), 'Standard_D4s_v3', 'Standard_B2s')]",
        "zone": "[string(add(mod(copyIndex('virtualMachines'), 3), 1))]",
        "dataDisks": [
          {
            "lun": 0,
            "diskSizeGB": "[if(equals(parameters('environment'), 'prod'), 1024, 128)]",
            "createOption": "Empty"
          }
        ]
      }
    }
  ]
}

Conditional Deployment Patterns

Deploy resources based on environment or feature flags:

{
  "condition": "[or(equals(parameters('environment'), 'staging'), equals(parameters('environment'), 'prod'))]",
  "type": "Microsoft.Network/applicationGateways",
  "apiVersion": "2023-04-01",
  "name": "[concat('agw-', parameters('projectName'), '-', parameters('environment'))]",
  "location": "[parameters('location')]",
  "properties": {
    "sku": {
      "name": "[if(equals(parameters('environment'), 'prod'), 'WAF_v2', 'Standard_v2')]",
      "tier": "[if(equals(parameters('environment'), 'prod'), 'WAF_v2', 'Standard_v2')]",
      "capacity": "[if(equals(parameters('environment'), 'prod'), 3, 1)]"
    },
    "webApplicationFirewallConfiguration": "[if(equals(parameters('environment'), 'prod'), createObject('enabled', true, 'firewallMode', 'Prevention', 'ruleSetType', 'OWASP', 'ruleSetVersion', '3.2'), null())]"
  }
}

Database Module with Environment Logic

Create environment-specific database configurations:

{
  "variables": {
    "environmentConfig": {
      "dev": {
        "sqlServerSku": "Basic",
        "databaseSku": {
          "name": "S0",
          "tier": "Standard"
        },
        "backupRetentionDays": 7,
        "geoRedundantBackup": "Disabled"
      },
      "staging": {
        "sqlServerSku": "Standard",
        "databaseSku": {
          "name": "S1",
          "tier": "Standard"
        },
        "backupRetentionDays": 14,
        "geoRedundantBackup": "Enabled"
      },
      "prod": {
        "sqlServerSku": "Premium",
        "databaseSku": {
          "name": "P1",
          "tier": "Premium"
        },
        "backupRetentionDays": 35,
        "geoRedundantBackup": "Enabled"
      }
    },
    "currentEnvironmentConfig": "[variables('environmentConfig')[parameters('environment')]]"
  },
  "resources": [
    {
      "type": "Microsoft.Sql/servers/databases",
      "apiVersion": "2023-05-01-preview",
      "name": "[concat(variables('sqlServerName'), '/', parameters('databases')[copyIndex()].name)]",
      "location": "[parameters('location')]",
      "copy": {
        "name": "databaseLoop",
        "count": "[length(parameters('databases'))]"
      },
      "dependsOn": [
        "[resourceId('Microsoft.Sql/servers', variables('sqlServerName'))]"
      ],
      "sku": "[variables('currentEnvironmentConfig').databaseSku]",
      "properties": {
        "collation": "[parameters('databases')[copyIndex()].collation]",
        "maxSizeBytes": "[parameters('databases')[copyIndex()].maxSizeBytes]",
        "catalogCollation": "SQL_Latin1_General_CP1_CI_AS",
        "zoneRedundant": "[if(equals(parameters('environment'), 'prod'), true, false)]",
        "readScale": "[if(equals(parameters('environment'), 'prod'), 'Enabled', 'Disabled')]",
        "requestedBackupStorageRedundancy": "[variables('currentEnvironmentConfig').geoRedundantBackup]"
      }
    }
  ]
}

Nested Copy Loops

Implement complex scenarios with nested copy operations:

{
  "type": "Microsoft.Compute/virtualMachines",
  "apiVersion": "2023-03-01",
  "name": "[variables('virtualMachines')[copyIndex()].name]",
  "copy": {
    "name": "vmLoop",
    "count": "[length(variables('virtualMachines'))]"
  },
  "dependsOn": [
    "nicLoop",
    "[resourceId('Microsoft.Compute/availabilitySets', variables('availabilitySetName'))]"
  ],
  "properties": {
    "availabilitySet": "[if(greater(parameters('vmCount'), 1), createObject('id', resourceId('Microsoft.Compute/availabilitySets', variables('availabilitySetName'))), null())]",
    "hardwareProfile": {
      "vmSize": "[variables('virtualMachines')[copyIndex()].size]"
    },
    "storageProfile": {
      "copy": [
        {
          "name": "dataDisks",
          "count": "[length(variables('virtualMachines')[copyIndex()].dataDisks)]",
          "input": {
            "lun": "[variables('virtualMachines')[copyIndex()].dataDisks[copyIndex('dataDisks')].lun]",
            "diskSizeGB": "[variables('virtualMachines')[copyIndex()].dataDisks[copyIndex('dataDisks')].diskSizeGB]",
            "createOption": "[variables('virtualMachines')[copyIndex()].dataDisks[copyIndex('dataDisks')].createOption]",
            "managedDisk": {
              "storageAccountType": "Premium_LRS"
            }
          }
        }
      ]
    }
  }
}

Template Deployment Script

Automate complex deployments with bash scripting:

#!/bin/bash

# Set variables
RESOURCE_GROUP="rg-webapp-${ENVIRONMENT}"
TEMPLATE_URI="https://raw.githubusercontent.com/your-repo/arm-templates/main/main-template.json"
PARAMETER_FILE="${ENVIRONMENT}.parameters.json"

# Create resource group if it doesn't exist
az group create --name $RESOURCE_GROUP --location $LOCATION

# Validate template
echo "Validating template..."
az deployment group validate \
  --resource-group $RESOURCE_GROUP \
  --template-uri $TEMPLATE_URI \
  --parameters @$PARAMETER_FILE

# Deploy template
echo "Deploying template..."
az deployment group create \
  --resource-group $RESOURCE_GROUP \
  --template-uri $TEMPLATE_URI \
  --parameters @$PARAMETER_FILE \
  --name "deployment-$(date +%Y%m%d-%H%M%S)"

# Get outputs
echo "Deployment outputs:"
az deployment group show \
  --resource-group $RESOURCE_GROUP \
  --name "deployment-$(date +%Y%m%d-%H%M%S)" \
  --query properties.outputs

Best Practices for Advanced Templates

Modular Design: Break complex templates into smaller, focused modules
Conditional Deployment: Use conditions to deploy resources based on environment or feature flags
Copy Loops: Leverage copy loops for creating multiple similar resources efficiently
Variable Calculations: Use variables with copy loops for complex object construction
Environment Configuration: Create environment-specific configurations using variables
Output Management: Provide comprehensive outputs for integration with other systems

Testing Complex Templates

# Test with different parameter combinations
for env in dev staging prod; do
  echo "Testing $env environment..."
  az deployment group validate \
    --resource-group "rg-test-$env" \
    --template-file main-template.json \
    --parameters @$env.parameters.json
done

# Test with different VM counts
for count in 1 3 5; do
  echo "Testing with $count VMs..."
  az deployment group validate \
    --resource-group "rg-test-scale" \
    --template-file main-template.json \
    --parameters @dev.parameters.json \
    --parameters vmCount=$count
done

What’s Next?

In Part 4, we’ll transition from ARM templates to Bicep, exploring how Bicep simplifies the authoring experience while maintaining all the power of ARM templates. We’ll convert our complex template to Bicep and explore Bicep-specific features.

We’ll discover:

Bicep syntax and structure
Converting ARM templates to Bicep
Bicep-specific features and improvements
Tooling and development experience
Migration strategies

This is Part 3 of our 7-part series on Infrastructure as Code with ARM Templates and Bicep. We’re mastering advanced patterns that enable enterprise-scale deployments.

Navigate<< Infrastructure as Code with ARM Templates and Bicep: Part 2 – Building Production-Ready InfrastructureInfrastructure as Code with ARM Templates and Bicep: Part 4 – Introduction to Bicep >>

Infrastructure as Code with ARM Templates and Bicep: Part 3 – Advanced ARM Template Patterns

What You’ll Learn

Template Modularity with Linked Templates

Copy Loops for Scaling Resources

Advanced Variable Copy Patterns

Conditional Deployment Patterns

Database Module with Environment Logic

Nested Copy Loops

Template Deployment Script

Best Practices for Advanced Templates

Testing Complex Templates

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What You’ll Learn

Template Modularity with Linked Templates

Copy Loops for Scaling Resources

Advanced Variable Copy Patterns

Conditional Deployment Patterns

Database Module with Environment Logic

Nested Copy Loops

Template Deployment Script

Best Practices for Advanced Templates

Testing Complex Templates

What’s Next?

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