Migrating Azure Keyvault

Azure Key Vault SDK Migration

Overview

Migrate from the deprecated Microsoft.Azure.KeyVault SDK to the modern Azure.Security.KeyVault.* libraries. The new SDK splits the single KeyVaultClient into resource-specific clients (SecretClient, KeyClient, CertificateClient) and uses Azure.Identity for authentication instead of custom token callbacks. Both synchronous and asynchronous APIs are available.

Package Reference Changes

Old References (Remove)

<PackageReference Include="Microsoft.Azure.KeyVault" Version="{any}" />
<PackageReference Include="Microsoft.Azure.KeyVault.Models" Version="{any}" />
<!-- Legacy authentication helper -->
<PackageReference Include="Microsoft.Azure.Services.AppAuthentication" Version="{any}" />

New References (Add)

<!-- Add only the packages for the resource types the project uses -->
<PackageReference Include="Azure.Security.KeyVault.Secrets" Version="{latest-stable}" />
<PackageReference Include="Azure.Security.KeyVault.Keys" Version="{latest-stable}" />
<PackageReference Include="Azure.Security.KeyVault.Certificates" Version="{latest-stable}" />

<!-- Unified authentication -->
<PackageReference Include="Azure.Identity" Version="{latest-stable}" />

Use tools or NuGet to find the latest stable versions. Only add the Azure.Security.KeyVault.* packages that the project actually needs.

Workflow

Migration Progress:
- [ ] Step 1: Detect Key Vault SDK usage
- [ ] Step 2: Update package references
- [ ] Step 3: Replace authentication
- [ ] Step 4: Replace client initialization
- [ ] Step 5: Convert secret operations
- [ ] Step 6: Convert key and certificate operations
- [ ] Step 7: Migrate error handling
- [ ] Step 8: Build and verify

Step 1: Detect Key Vault SDK Usage

Scan the project for:

• using Microsoft.Azure.KeyVault; and using Microsoft.Azure.KeyVault.Models;
• Types: KeyVaultClient, SecretBundle, KeyBundle, CertificateBundle
• Methods: GetSecretAsync, SetSecretAsync, GetKeyAsync, GetCertificateAsync
• Authentication patterns: KeyVaultClient.AuthenticationCallback, AzureServiceTokenProvider

Step 2: Update Package References

Remove Microsoft.Azure.KeyVault, Microsoft.Azure.KeyVault.Models, and Microsoft.Azure.Services.AppAuthentication from the project file. Add the appropriate Azure.Security.KeyVault.* and Azure.Identity packages.

Step 3: Replace Authentication

// Old — custom token callback
var azureServiceTokenProvider = new AzureServiceTokenProvider();
var client = new KeyVaultClient(
    new KeyVaultClient.AuthenticationCallback(
        azureServiceTokenProvider.KeyVaultTokenCallback));

// New — Azure.Identity (works with managed identity, Azure CLI, Visual Studio, etc.)
var credential = new DefaultAzureCredential();

DefaultAzureCredential chains multiple authentication methods automatically. For production scenarios that need a specific identity, use ManagedIdentityCredential, ClientSecretCredential, or another concrete type from Azure.Identity.

Step 4: Replace Client Initialization

// Old — single client for all resource types
var client = new KeyVaultClient(authCallback);

// New — one client per resource type
var vaultUri = new Uri("https://my-vault.vault.azure.net/");
var secretClient = new SecretClient(vaultUri, credential);
var keyClient = new KeyClient(vaultUri, credential);
var certificateClient = new CertificateClient(vaultUri, credential);

Step 5: Convert Secret Operations

// Old
SecretBundle secret = await client.GetSecretAsync(vaultBaseUrl, "my-secret");
string value = secret.Value;

await client.SetSecretAsync(vaultBaseUrl, "my-secret", "new-value");

// New
KeyVaultSecret secret = await secretClient.GetSecretAsync("my-secret");
string value = secret.Value;

await secretClient.SetSecretAsync("my-secret", "new-value");

The new client takes the vault URI at construction — pass only the secret name to each operation.

Step 6: Convert Key and Certificate Operations

// Old — Keys
KeyBundle key = await client.GetKeyAsync(vaultBaseUrl, "my-key");

// New — Keys
KeyVaultKey key = await keyClient.GetKeyAsync("my-key");

// Old — Certificates
CertificateBundle cert = await client.GetCertificateAsync(vaultBaseUrl, "my-cert");

// New — Certificates
KeyVaultCertificateWithPolicy cert = await certificateClient.GetCertificateAsync("my-cert");

Step 7: Migrate Error Handling

// Old
try { /* operation */ }
catch (KeyVaultErrorException ex) when (ex.Response.StatusCode == HttpStatusCode.NotFound)
{ /* handle */ }

// New
try { /* operation */ }
catch (RequestFailedException ex) when (ex.Status == 404)
{ /* handle */ }

RequestFailedException is the unified exception type across all Azure.* client libraries.

Step 8: Build and Verify

1. Build the project:

   dotnet build
   

2. Verify authentication works in the target environment (local development, CI, Azure)
3. Test secret retrieval and any key/certificate operations against a development vault

API Differences

Troubleshooting

Authentication Failures with DefaultAzureCredential

DefaultAzureCredential tries multiple credential sources in order. If it fails, check that at least one source is configured: Azure CLI login (az login), Visual Studio authentication, environment variables (AZURE_CLIENT_ID, AZURE_TENANT_ID, AZURE_CLIENT_SECRET), or managed identity. Enable logging with AzureEventSourceListener to see which credential is attempted.

Vault URL No Longer Passed Per-Call

The new clients take the vault URI in the constructor. If the old code used different vault URLs for different operations, create separate client instances for each vault.

Missing SecretBundle or KeyBundle Types

These types are replaced by KeyVaultSecret and KeyVaultKey in the new SDK. Update all variable declarations and return types. Properties like SecretBundle.Value map directly to KeyVaultSecret.Value.

Package Version Conflicts with Other Azure SDKs

The new Key Vault libraries depend on Azure.Core. If other Azure SDK packages are present, ensure all packages use compatible Azure.Core versions to avoid binding redirect issues.