Variables

• Variables are value which can be manipulated with in the templated
• Variable syntax can be found here

Using Copy Effectively

• Starting from where we left in the last article. We have removed the count parameter & added a variable for network name.
• Used a function to populate the resource location
• With these changes, the script looks something like this

{
    "$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
    "contentVersion" : "1.0.0.0",
    "parameters": {
        "vnetaddresspace": {
            "type": "array",
            "defaultValue":["192.168.0.0/16"] 

        },
        "subnetnames":{
            "type": "array",
            "defaultValue": ["web", "business","data"]
        },
        "subnetAddress":{
            "type": "array",
            "defaultValue": ["192.168.0.0/24","192.168.1.0/24", "192.168.2.0/24"]
        }
    },
    "variables":{
        "vnetname": "ntier"
    },
    "resources":[
        {
            "name": "[variables('vnetname')]",
            "type": "Microsoft.Network/virtualNetworks",
            "apiVersion": "2019-04-01",
            "location": "[resourceGroup().location]",
            "properties": {
                "addressSpace": {
                    "addressPrefixes": "[parameters('vnetaddresspace')]"
                }

            } 
        },
        {
            "name": "[concat(variables('vnetname'),'/',parameters('subnetnames')[copyIndex()])]",
            "type": "Microsoft.Network/virtualNetworks/subnets",
            "apiVersion": "2019-04-01",
            "properties": {
                "addressPrefix": "[parameters('subnetAddress')[copyIndex()]]"
            },
            "dependsOn": ["[variables('vnetname')]"],
            "copy": { 
                "name": "websitescopy", 
                "count": "[length(parameters('subnetnames'))]",
                "mode": "serial"
            }
                        
        }

    ]

}

• Lets add an simple output to the template. In this case i will be adding the count of subnets as output. Refer here for more info.

{
    "$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
    "contentVersion" : "1.0.0.0",
    "parameters": {
        "vnetaddresspace": {
            "type": "array",
            "defaultValue":["192.168.0.0/16"] 

        },
        "subnetnames":{
            "type": "array",
            "defaultValue": ["web", "business","data"]
        },
        "subnetAddress":{
            "type": "array",
            "defaultValue": ["192.168.0.0/24","192.168.1.0/24", "192.168.2.0/24"]
        }
    },
    "variables":{
        "vnetname": "ntier"
    },
    "resources":[
        {
            "name": "[variables('vnetname')]",
            "type": "Microsoft.Network/virtualNetworks",
            "apiVersion": "2019-04-01",
            "location": "[resourceGroup().location]",
            "properties": {
                "addressSpace": {
                    "addressPrefixes": "[parameters('vnetaddresspace')]"
                }

            } 
        },
        {
            "name": "[concat(variables('vnetname'),'/',parameters('subnetnames')[copyIndex()])]",
            "type": "Microsoft.Network/virtualNetworks/subnets",
            "apiVersion": "2019-04-01",
            "properties": {
                "addressPrefix": "[parameters('subnetAddress')[copyIndex()]]"
            },
            "dependsOn": ["[variables('vnetname')]"],
            "copy": { 
                "name": "websitescopy", 
                "count": "[length(parameters('subnetnames'))]",
                "mode": "serial"
            }
                        
        }

    ],
    "outputs": {
        "subnets-count": {
            "type": "int",
            "value": "[length(parameters('subnetnames'))]"
        }
    }

}

• Try to create deployment and look at the outputs section

• Microsoft has developed lot of sample templates for various deployments. Refer Here

• If you would like to create user defined functions with in arm template, Refer Here

Whats left

• How can i call existing template from my arm template
• How to create parameters file
• How do i execute arm templates from CLI and Powershell