ARM template array lookup

arm-template-array-lookup.json

{
  "$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0",
  "parameters": {
    "vnet": {
      "type": "string",
      "defaultValue": "resource-group/vnet-name"
    },
    "ipAddress": {
      "type": "string",
      "defaultValue": ""
    }
  },
  "variables": {
    "convertToVnet": [
      {
        "resourceGroup": "[resourceGroup().name]",
        "name": "[parameters('vnet')]"
      },
      {
        "resourceGroup": "[split(parameters('vnet'),'/')[0]]",
        "name": "[split(concat(parameters('vnet'),'/'),'/')[1]]"
      }
    ],
    "vnet": "[variables('convertToVnet')[sub(length(split(parameters('vnet'),'/')),1)]]",
    "ipAddressHasValue": "[length(trim(parameters('ipAddress'), 1))]",
    "convertToPrivateIpConfiguration": [
      {
        "privateIPAddress": null,
        "privateIPAllocationMethod": "Dynamic"
      },
      {
        "privateIPAddress": "[parameters('ipAddress')]",
        "privateIPAllocationMethod": "Static"
      }
    ],
    "privateIpConfiguration": "[variables('convertToPrivateIpConfiguration')[variables('ipAddressHasValue')]]"
  },
  "resources": [],
  "outputs": {
    "vnet": {
      "value": "[variables('vnet')]",
      "type" : "object"
    },
    "privateIpConfiguration": {
      "value": "[variables('privateIpConfiguration')]",
      "type" : "object"
    }
  }
}