Azure Policy evaluation fails when parameter is string - azure

Question

I'm struggling with a policy which should allow only certain values for tags.
Here is the code
{
"mode": "Indexed",
"policyRule": {
"if": {
"allOf": [
{
"field": "type",
"equals": "Microsoft.Compute/virtualMachines"
},
{
"field": "[concat('tags[', parameters('tagName'), ']')]",
"notIn": "[parameters('listOfAllowedValues')]"
}
]
},
"then": {
"effect": "deny"
}
},
"parameters": {
"tagName": {
"type": "String",
"metadata": {
"displayName": "Tag Name",
"description": "Name of the tag, such as 'environment'"
}
},
"listOfAllowedValues": {
"type": "Array",
"metadata": {
"displayName": "Allowed values",
"description": "The list of values which tag can have."
}
}
}
}
I put this array for assigments: ["Not Appliable","1","2","3","4"]
Policy evaluation works perfectly fine for numbers, but when I put tag value to be Not applicable policy always denies creation of VM.
Not sure what's wrong with it..Any help is appreciated!

Answer 1

In your policy definition, for the parameter listOfAllowedValues you are passing the allowed values as Notappliable and while creating the virtual machine you are passing the tag value as NotApplicable since there is spelling mistake that is the reason your policy valuation is getting failed.
I have test the above policy in my local and it working as expected from my end.