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Allow apps to access Azure Stack Hub Key Vault secrets

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The steps in this article describe how to run the sample app HelloKeyVault that retrieves keys and secrets from a key vault in Azure Stack Hub.

Prerequisites

You can install the following prerequisites from the Azure Stack Development Kit, or from a Windows-based external client if you're connected through VPN:

Create a key vault and register an app

To prepare for the sample application:

  • Create a key vault in Azure Stack Hub.
  • Register an app in Microsoft Entra ID.

Use the Azure portal or PowerShell to prepare for the sample app.

Note

By default, the PowerShell script creates a new app in Active Directory. However, you can register one of your existing applications.

Before running the following script, make sure you provide values for the aadTenantName and applicationPassword variables. If you don't specify a value for applicationPassword, this script generates a random password.

$vaultName           = 'myVault'
$resourceGroupName   = 'myResourceGroup'
$applicationName     = 'myApp'
$location            = 'local'

# Password for the application. If not specified, this script generates a random password during app creation.
$applicationPassword = ''

# Function to generate a random password for the application.
Function GenerateSymmetricKey()
{
    $key = New-Object byte[](32)
    $rng = [System.Security.Cryptography.RNGCryptoServiceProvider]::Create()
    $rng.GetBytes($key)
    return [System.Convert]::ToBase64String($key)
}

Write-Host 'Please log into your Azure Stack Hub user environment' -foregroundcolor Green

$tenantARM = "https://management.local.azurestack.external"
$aadTenantName = "FILL THIS IN WITH YOUR AAD TENANT NAME. FOR EXAMPLE: myazurestack.onmicrosoft.com"

# Configure the Azure Stack Hub operator's PowerShell environment.
Add-AzEnvironment `
  -Name "AzureStackUser" `
  -ArmEndpoint $tenantARM

$TenantID = Get-AzsDirectoryTenantId `
  -AADTenantName $aadTenantName `
  -EnvironmentName AzureStackUser

# Sign in to the user portal.
Connect-AzAccount `
  -EnvironmentName "AzureStackUser" `
  -TenantId $TenantID `

$now = [System.DateTime]::Now
$oneYearFromNow = $now.AddYears(1)

$applicationPassword = GenerateSymmetricKey

# Create a new Azure AD application.
$identifierUri = [string]::Format("http://localhost:8080/{0}",[Guid]::NewGuid().ToString("N"))
$homePage = "https://contoso.com"

Write-Host "Creating a new AAD Application"
$ADApp = New-AzADApplication `
  -DisplayName $applicationName `
  -HomePage $homePage `
  -IdentifierUris $identifierUri `
  -StartDate $now `
  -EndDate $oneYearFromNow `
  -Password $applicationPassword

Write-Host "Creating a new AAD service principal"
$servicePrincipal = New-AzADServicePrincipal `
  -ApplicationId $ADApp.ApplicationId

# Create a new resource group and a key vault in that resource group.
New-AzResourceGroup `
  -Name $resourceGroupName `
  -Location $location

Write-Host "Creating vault $vaultName"
$vault = New-AzKeyVault -VaultName $vaultName `
  -ResourceGroupName $resourceGroupName `
  -Sku standard `
  -Location $location

# Specify full privileges to the vault for the application.
Write-Host "Setting access policy"
Set-AzKeyVaultAccessPolicy -VaultName $vaultName `
  -ObjectId $servicePrincipal.Id `
  -PermissionsToKeys all `
  -PermissionsToSecrets all

Write-Host "Paste the following settings into the app.config file for the HelloKeyVault project:"
'<add key="VaultUrl" value="' + $vault.VaultUri + '"/>'
'<add key="AuthClientId" value="' + $servicePrincipal.ApplicationId + '"/>'
'<add key="AuthClientSecret" value="' + $applicationPassword + '"/>'
Write-Host

The following image shows the output from the script used to create the key vault:

Key vault with access keys

Make a note of the VaultUrl, AuthClientId, and AuthClientSecret values returned by the previous script. You use these values to run the HelloKeyVault application.

Download and configure the sample application

Download the key vault sample from the Azure Key Vault client samples page. Extract the contents of the .zip file on your development workstation. There are two apps in the samples folder; this article uses HelloKeyVault.

To load the HelloKeyVault sample:

  1. Browse to the Microsoft.Azure.KeyVault.Samples > samples > HelloKeyVault folder.
  2. Open the HelloKeyVault app in Visual Studio.

Configure the sample application

In Visual Studio:

  1. Open the HelloKeyVault\App.config file and find the <appSettings> element.

  2. Update the VaultUrl, AuthClientId, and AuthCertThumbprint keys with the values returned when creating the key vault. By default, the App.config file has a placeholder for AuthCertThumbprint. Replace this placeholder with AuthClientSecret.

    <appSettings>
 <!-- Update these settings for your test environment -->
 <add key="VaultUrl" value="URL to your Vault" />
 <add key="AuthClientId" value="Client Id of your Service Principal" />
 <add key="AuthCertThumbprint" value="Thumbprint of the certificate used for authentication" />
 <add key="TracingEnabled" value="false" />
</appSettings>

  3. Rebuild the solution.

Run the app

When you run HelloKeyVault, the app signs in to Microsoft Entra ID and then uses the AuthClientSecret token to authenticate to the key vault in Azure Stack Hub.

You can use the HelloKeyVault sample to:

  • Perform basic operations such as create, encrypt, wrap, and delete on the keys and secrets.
  • Pass parameters such as encrypt and decrypt to HelloKeyVault, and apply the specified changes to a key vault.

Next steps