Forcing naming convention using Policy

Question

I would like to know if I can define a policy where I can add a prefix followed by '-' and then variable length of numbers or characters.
I cannot find a logical operator to define variable length in Azure policy as whatever I try is not working.

"policyRule": {
"if": {
"allOf": [
{
"field": "type",
"match": "Microsoft.Compute/virtualMachines"
},
{
"not": {
"field": "name",
"matchInsensitively": "ash361-.....`"

ash361-..... works if I name VM as ash361-abcde or ASH361-12345
but what I want is that prefix is required but then add whatever number of characters for example 'ash361-uciptvm67' or 'ash361-cisIPT4367'

I tried 'ash361-.*' but that did not work.

is there an operator for variable length?

Answer 1

@Ashar Siddiqui Welcome to Microsoft Q & A Community Forum. For your requirement , you can use below sample snippet to verify the prefix of the VM name and also vm name can be any number of characters.

{  
  "mode": "All",  
  "policyRule": {  
    "if": {  
      "allOf": [  
        {  
          "not": {  
            "value": "[substring(field('name'), 0, 3)]",  
            "equals": "swa"  
          }  
        },  
        {  
          "field": "type",  
          "equals": "Microsoft.Compute/virtualMachines"  
        }  
      ]  
    },  
    "then": {  
      "effect": "deny"  
    }  
  },  
  "parameters": {}  
}  

Also, to check length of the VM name , you can use this value operator "[length(field('name'))]" in your policy definition.