Use Azure Key Vault to pass secure parameter value during deployment

Instead of putting a secure value (like a password) directly in your parameter file, you can retrieve the value from an Azure Key Vault during a deployment. You retrieve the value by referencing the key vault and secret in your parameter file. The value is never exposed because you only reference its key vault ID. The key vault can exist in a different subscription than the resource group you are deploying to.

Note

This article has been updated to use the new Azure PowerShell Az module. To learn more about the new Az module and AzureRM compatibility, see Introducing the new Azure PowerShell Az module. For installation instructions, see Install Azure PowerShell.

Deploy key vaults and secrets

To create Key Vaults and add secrets, see:

There are some addition considerations and requirements when integrating Key Vault with Resource Manager template deployment:

  • enabledForTemplateDeployment is a key vault property. To access the secrets inside this Key Vault from Resource Manager deployment, enabledForTemplateDeployment must be true.
  • If you are not the owner of the key vault, the owner must update the key vault security policy settings for you to add secrets.

The following Azure CLI and Azure PowerShell samples show how it is done:

# Create a Key Vault
az keyvault create \
  --name $keyVaultName \
  --resource-group $resourceGroupName \
  --location $location \
  --enabled-for-template-deployment true
az keyvault set-policy --upn $userPrincipalName --name $keyVaultName --secret-permissions set delete get list
New-AzKeyVault `
  -VaultName $keyVaultName `
  -resourceGroupName $resourceGroupName `
  -Location $location `
  -EnabledForTemplateDeployment
Set-AzKeyVaultAccessPolicy -VaultName $keyVaultName -UserPrincipalName $userPrincipalName -PermissionsToSecrets set,delete,get,list

Grant access to the secrets

The user who deploys the template must have the Microsoft.KeyVault/vaults/deploy/action permission for scope that contains the Key Vault including resource group and Key Vault. The Owner and Contributor roles both grant this access. If you create the Key Vault, you are the owner so you have the permission. If the Key Vault is under a different subscription, the owner of the Key Vault must grand the access.

The following procedure shows how to create a role with the minimum permission, and how to assign the user

  1. Create a custom role definition JSON file:

    {
      "Name": "Key Vault resource manager template deployment operator",
      "IsCustom": true,
      "Description": "Lets you deploy a resource manager template with the access to the secrets in the Key Vault.",
      "Actions": [
        "Microsoft.KeyVault/vaults/deploy/action"
      ],
      "NotActions": [],
      "DataActions": [],
      "NotDataActions": [],
      "AssignableScopes": [
        "/subscriptions/00000000-0000-0000-0000-000000000000"
      ]
    }
    

    Replace "00000000-0000-0000-0000-000000000000" with the subscription ID of the user who needs to deploy the templates.

  2. Create the new role using the JSON file:

    $resourceGroupName= "<Resource Group Name>" # the resource group which contains the Key Vault
    $userPrincipalName = "<Email Address of the deployment operator>"
    New-AzRoleDefinition -InputFile "<PathToTheJSONFile>" 
    New-AzRoleAssignment -ResourceGroupName $resourceGroupName -RoleDefinitionName "Key Vault resource manager template deployment operator" -SignInName $userPrincipalName
    

    The New-AzRoleAssignment sample assigns the custom role to the user on the resource group level.

When using a Key Vault with the template for a Managed Application, you must grant access to the Appliance Resource Provider service principal. For more information, see Access Key Vault secret when deploying Azure Managed Applications.

Reference secrets with static ID

With this approach, you reference the key vault in the parameter file, not the template. The following image shows how the parameter file references the secret and passes that value to the template.

Resource Manager key vault integration Static ID diagram

Tutorial: Integrate Azure Key Vault in Resource Manager Template deployment uses this method. The tutorial deploy a virtual machine what includes an administrator password. The password parameter is set to a secure string:

Resource Manager key vault integration static ID template file

Now, create a parameter file for the preceding template. In the parameter file, specify a parameter that matches the name of the parameter in the template. For the parameter value, reference the secret from the key vault. You reference the secret by passing the resource identifier of the key vault and the name of the secret:

Resource Manager key vault integration static ID parameter file

If you need to use a version of the secret other than the current version, use the secretVersion property.

"secretName": "examplesecret",
"secretVersion": "cd91b2b7e10e492ebb870a6ee0591b68"

Deploy the template and pass in the parameter file:

For Azure CLI, use:

az group create --name $resourceGroupName --location $location
az group deployment create \
    --resource-group $resourceGroupName \
    --template-uri <The Template File URI> \
    --parameters <The Parameter File>

For PowerShell, use:

New-AzResourceGroup -Name $resourceGroupName -Location $location
New-AzResourceGroupDeployment `
  -ResourceGroupName $resourceGroupName `
  -TemplateUri <The Template File URI> `
  -TemplateParameterFile <The Parameter File>

Reference secrets with dynamic ID

The previous section showed how to pass a static resource ID for the key vault secret from the parameter. However, in some scenarios, you need to reference a key vault secret that varies based on the current deployment. Or, you may want to pass parameter values to the template rather than create a reference parameter in the parameter file. In either case, you can dynamically generate the resource ID for a key vault secret by using a linked template.

You can't dynamically generate the resource ID in the parameters file because template expressions aren't allowed in the parameters file.

In your parent template, you add the linked template and pass in a parameter that contains the dynamically generated resource ID. The following image shows how a parameter in the linked template references the secret.

Dynamic ID

The following template dynamically creates the key vault ID and passes it as a parameter.

{
    "$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
    "contentVersion": "1.0.0.0",
    "parameters": {
        "location": {
            "type": "string",
            "defaultValue": "[resourceGroup().location]",
            "metadata": {
                "description": "The location where the resources will be deployed."
            }
        },
        "vaultName": {
            "type": "string",
            "metadata": {
                "description": "The name of the keyvault that contains the secret."
            }
        },
        "secretName": {
            "type": "string",
            "metadata": {
                "description": "The name of the secret."
            }
        },
        "vaultResourceGroupName": {
            "type": "string",
            "metadata": {
                "description": "The name of the resource group that contains the keyvault."
            }
        },
        "vaultSubscription": {
            "type": "string",
            "defaultValue": "[subscription().subscriptionId]",
            "metadata": {
                "description": "The name of the subscription that contains the keyvault."
            }
        },
        "_artifactsLocation": {
            "type": "string",
            "metadata": {
                "description": "The base URI where artifacts required by this template are located. When the template is deployed using the accompanying scripts, a private location in the subscription will be used and this value will be automatically generated."
            },
            "defaultValue": "https://raw.githubusercontent.com/Azure/azure-quickstart-templates/master/201-key-vault-use-dynamic-id/"
        },
        "_artifactsLocationSasToken": {
            "type": "securestring",
            "metadata": {
                "description": "The sasToken required to access _artifactsLocation.  When the template is deployed using the accompanying scripts, a sasToken will be automatically generated."
            },
            "defaultValue": ""
        }
    },
    "resources": [
        {
            "apiVersion": "2018-05-01",
            "name": "dynamicSecret",
            "type": "Microsoft.Resources/deployments",
            "properties": {
                "mode": "Incremental",
                "templateLink": {
                    "contentVersion": "1.0.0.0",
                    "uri": "[uri(parameters('_artifactsLocation'), concat('./nested/sqlserver.json', parameters('_artifactsLocationSasToken')))]"
                },
                "parameters": {
                    "location": {
                        "value": "[parameters('location')]"
                    },
                    "adminLogin": {
                        "value": "ghuser"
                    },
                    "adminPassword": {
                        "reference": {
                            "keyVault": {
                                "id": "[resourceId(parameters('vaultSubscription'), parameters('vaultResourceGroupName'), 'Microsoft.KeyVault/vaults', parameters('vaultName'))]"
                            },
                            "secretName": "[parameters('secretName')]"
                        }
                    }
                }
            }
        }
    ],
    "outputs": {
        "sqlFQDN": {
            "type": "string",
            "value": "[reference('dynamicSecret').outputs.sqlFQDN.value]"
        }
    }
}

Deploy the preceding template, and provide values for the parameters. You can use the example template from GitHub, but you must provide parameter values for your environment.

For Azure CLI, use:

az group create --name $resourceGroupName --location $location
az group deployment create \
    --resource-group $resourceGroupName \
    --template-uri https://raw.githubusercontent.com/Azure/azure-quickstart-templates/master/201-key-vault-use-dynamic-id/azuredeploy.json \
    --parameters vaultName=$keyVaultName vaultResourceGroupName=examplegroup secretName=examplesecret

For PowerShell, use:

New-AzResourceGroup -Name $resourceGroupName -Location $location
New-AzResourceGroupDeployment `
  -ResourceGroupName $resourceGroupName `
  -TemplateUri https://raw.githubusercontent.com/Azure/azure-quickstart-templates/master/201-key-vault-use-dynamic-id/azuredeploy.json `
  -vaultName $keyVaultName -vaultResourceGroupName $keyVaultResourceGroupName -secretName $secretName

Next steps