ARM Template concatenate objects

Question

I am trying to set up some tags within an ARM template in accordance with this article: https://docs.microsoft.com/en-us/azure/azure-resource-manager/resource-manager-templates-resources#apply-an-object-to-the-tag-element

I wanted to be able to set up a couple of generic tags in the TagValues parameter, but then append others for specific resources. Is this possible, and if so how? I've tried using [concat()] but it's not happy dealing with objects, and fails validation.

Here's an example of what I'm trying to do:

{
  "$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "tagValues": {
      "type": "object",
      "defaultValue": {
        "Dept": "Finance",
        "Environment": "Production"
      }
    }
  },
  "resources": [
    {
      "apiVersion": "2016-01-01",
      "type": "Microsoft.Storage/storageAccounts",
      "name": "[concat('storage', uniqueString(resourceGroup().id))]",
      "location": "[resourceGroup().location]",
      "tags": "[parameters('tagValues')]",     // want to concatenate another tag here, so that the following is returned: "Dept": "Finance", "Environment": "Production", "myExtraTag": "myTagValue"
      "sku": {
        "name": "Standard_LRS"
      },
      "kind": "Storage",
      "properties": {}
    }
{
          "apiVersion": "2016-01-01",
          "type": "Microsoft.Storage/storageAccounts",
          "name": "mySecondResource",
          "location": "[resourceGroup().location]",
          "tags": "[parameters('tagValues')]",     // want to concatenate a DIFFERENT tag here, so that the following is returned: "Dept": "Finance", "Environment": "Production", "myExtraDifferentTag": "myDifferentTagValue"
          "sku": {
            "name": "Standard_LRS"
          },
          "kind": "Storage",
          "properties": {}
        }
  ]
}

Answer 1

It's possible with union function. You can find more documentation about it here

Below solution might work for you. I have given 2 approaches. One with inline string converted to object with json function. Other approach is to create an object in variables and using union to concatenate both objects.

    {
  "$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "tagValues": {
      "type": "object",
      "defaultValue": {
        "Dept": "Finance",
        "Environment": "Production"
      }
    }
  },
  "variables" : {
     "customTag" : {"myExtraDifferentTag": "myDifferentTagValue", "myAnotherExtraDifferentTag": "myAnotherDifferentTagValue"}
  },
  "resources": [
    {
      "apiVersion": "2016-01-01",
      "type": "Microsoft.Storage/storageAccounts",
      "name": "[concat('storage', uniqueString(resourceGroup().id))]",
      "location": "[resourceGroup().location]",
      "tags": "[union(parameters('tagValues'),json('{\"myExtraTag\":\"myTagValue \"}'))]",  //Concatenates `tagValues` object to inline object    
      "sku": {
        "name": "Standard_LRS"
      },
      "kind": "Storage",
      "properties": {}
    }
{
          "apiVersion": "2016-01-01",
          "type": "Microsoft.Storage/storageAccounts",
          "name": "mySecondResource",
          "location": "[resourceGroup().location]",
          "tags": "[union(parameters('tagValues'),variables('customTag'))]",     // Concatenates `tagValues` object to `customTag` object
          "sku": {
            "name": "Standard_LRS"
          },
          "kind": "Storage",
          "properties": {}
        }
  ]
}

Answer 2

Good question Greg!

You can achieve what you are after with the below:

{
  "$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "variables": {
      "testvar": "customtagfromvar"
  },
  "parameters": {
  },
  "resources": [
    {
      "apiVersion": "2016-01-01",
      "type": "Microsoft.Storage/storageAccounts",
      "name": "[concat('storage', uniqueString(resourceGroup().id))]",
      "location": "[resourceGroup().location]",
      "tags": {
          "department": "Finance",
          "customTag": "[concat(variables('testvar'), '-concatedtext')]"
      },
      "sku": {
        "name": "Standard_LRS"
      },
      "kind": "Storage",
      "properties": {}
    }
  ]
}

Hope this helps!