Duplicate Properties in Arm Templates

When troubleshooting an Azure Resource Manager template, be sure to validate that there are not duplicate properties that exist in the parameters.json file.

We were building an IoT Hub template for quick deployment in multiple regions on Azure. In the template, we wanted to add a “routing” property to the json to create endpoints and routes for the IoT Hub.

The resource provider for the IoT Hub did not reply with any error messages, only a success message and the end results being that our endpoints and routes did not exist in the Azure portal.

An example of our json to create these endpoints.

        "routing": {
          "endpoints": {
            "serviceBusQueues": [],
            "serviceBusTopics": [],
            "eventHubs": [
              {
                "connectionString": "[concat('Endpoint=sb://', parameters('iotHubServiceBusName'), '.servicebus.windows.net:5671/;SharedAccessKeyName=RootManageSharedAccessKey;SharedAccessKey=', parameters('iotHubServiceBusKey'), ';EntityPath=hubdata')]",
                "name": "Hub",
                "subscriptionId": "...",
                "resourceGroup": "iotdata"
              }
            ]
          },
          "routes": [
            {
              "name": "Route",
              "source": "DeviceMessages",
              "condition": "payloadType = \"Data\"",
              "endpointNames": [
                "Energy"
              ],
              "isEnabled": true
            }
          ]
        },

The problem is that in our Azure Resource Manager template, further down in the json we had another “routing” property that looked like the following code.

        "routing": {
        }

Because of this our IoT Hub instance in the Azure portal was taking the second definition and not deploying any endpoints or routes to the IoT Hub instance.

In a future post, we will walk through utilizing the azure-arm-validator on GitHub to ensure that the json is valid.

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