Deny-UDR-With-Specific-NextHop.json

{
  "name": "Deny-UDR-With-Specific-NextHop",
  "type": "Microsoft.Authorization/policyDefinitions",
  "apiVersion": "2021-06-01",
  "scope": null,
  "properties": {
    "policyType": "Custom",
    "mode": "All",
    "displayName": "User Defined Routes with 'Next Hop Type' set to 'Internet' or 'VirtualNetworkGateway' should be denied",
    "description": "This policy denies the creation of a User Defined Route with 'Next Hop Type' set to 'Internet' or 'VirtualNetworkGateway'.",
    "metadata": {
      "version": "1.0.0",
      "category": "Network",
      "source": "https://github.com/Azure/Enterprise-Scale/",
      "alzCloudEnvironments": [
        "AzureCloud",
        "AzureChinaCloud",
        "AzureUSGovernment"
      ]
    },
    "parameters": {
      "effect": {
        "type": "String",
        "metadata": {
          "displayName": "Effect",
          "description": "The effect determines what happens when the policy rule is evaluated to match"
        },
        "allowedValues": [
          "Audit",
          "Deny",
          "Disabled"
        ],
        "defaultValue": "Deny"
      },
      "excludedDestinations": {
        "type": "Array",
        "metadata": {
          "displayName": "Excluded Destinations",
          "description": "Array of route destinations that are to be denied"
        },
        "defaultValue": [
          "Internet", 
          "VirtualNetworkGateway"
        ]
      }
    },
    "policyRule": {
      "if": {
        "anyOf": [
          {
            "allOf": [
              {
                "equals": "Microsoft.Network/routeTables",
                "field": "type"
              },
              {
                "count": {
                  "field": "Microsoft.Network/routeTables/routes[*]",
                  "where": {
                        "field": "Microsoft.Network/routeTables/routes[*].nextHopType",
                        "in": "[[parameters('excludedDestinations')]"
                  }
                },
                "notEquals": 0
              }
            ]
          },
          {
            "allOf": [
              {
              "field": "type",
              "equals": "Microsoft.Network/routeTables/routes"
              },
              {
              "field": "Microsoft.Network/routeTables/routes/nextHopType",
              "in": "[[parameters('excludedDestinations')]"
              }
            ]
          }
        ]
      },
      "then": {
        "effect": "[[parameters('effect')]"
      }
    }
  }
}