Azure Policy - Enforce location for CosmosDB

Now, it’s very easy on Azure to limit allowed locations for your services. Azure has a built in Azure Policy for this use case.

Reminder, the policy to limit allowed location of your ressources is :

"if": {
    "allOf": [
        {
            "field": "location",
            "notIn": "[parameters('listOfAllowedLocations')]"
        },
        {
            "field": "location",
            "notEquals": "global"
        }
    ]
},
"then": {
    "effect": "deny"
}  

You must add location of your choice. Don’t forget to add global location if you want use not regional services like DNS Zone.

Now, on CosmosDB, with this policy if you have selected only North Europe and West Europe as allowed locations, you can create your Cosmos DB only on this two locations.

However, Cosmos DB have a feature to create a replica on an another region like France Central. Even if you have the policy, you can create the replica..

If you want deny creation of your replicas, you must create a custom policy with this defintion :

{
  "mode": "All",
  "policyRule": {
    "if": {
      "allOf": [
        {
          "field": "type",
          "equals": "Microsoft.DocumentDB/databaseAccounts"
        },
        {
          "not": {
            "field": "Microsoft.DocumentDB/databaseAccounts/Locations[*].locationName",
            "in": "[parameters('allowedLocations')]"
          }
        }
      ]
    },
    "then": {
      "effect": "deny"
    }
  },
  "parameters": {
    "allowedLocations": {
      "type": "Array",
      "metadata": {
        "displayName": "Allowed locations",
        "description": "The list of allowed locations for resources."
      }
    }
  }
}

For your parameters, it’s not possible to use the strong type, we must use a list and use this parameter : westeurope;northeurope;West Europe;North Europe