Azure Key Vault secret client library for .NET

Azure Key Vault is a cloud service that provides a secure storage of secrets, such as passwords and database connection strings.

The secret client library allows you to securely store and control the access to tokens, passwords, API keys, and other secrets. This library offers operations to create, retrieve, update, delete, purge, backup, restore and list the secrets and its versions.

Source code | Package (NuGet) | API reference documentation | Product documentation | Samples

Getting started

Install the package

Install the Azure Key Vault client library for .NET with NuGet:

Install-Package Azure.Security.KeyVault.Secrets -IncludePrerelease

Prerequisites

• An Azure subscription.
• An existing Key Vault. If you need to create a Key Vault, you can use the Azure Portal or Azure CLI.

If you use the Azure CLI, replace <your-resource-group-name> and <your-key-vault-name> with your own, unique names:

az keyvault create --resource-group <your-resource-group-name> --name <your-key-vault-name>

Authenticate the client

In order to interact with the Key Vault service, you'll need to create an instance of the SecretClient class. You would need a vault url, which you may see as "DNS Name" in the portal, and client secret credentials (client id, client secret, tenant id) to instantiate a client object.

Client secret credential authentication is being used in this getting started section but you can find more ways to authenticate with Azure identity. To use the DefaultAzureCredential provider shown below, or other credential providers provided with the Azure SDK, you should install the Azure.Identity package:

Install-Package Azure.Identity

Create/Get credentials

Use the Azure CLI snippet below to create/get client secret credentials.

• Create a service principal and configure its access to Azure resources:

  az ad sp create-for-rbac -n <your-application-name> --skip-assignment
  

  Output:

  {
      "appId": "generated-app-ID",
      "displayName": "dummy-app-name",
      "name": "http://dummy-app-name",
      "password": "random-password",
      "tenant": "tenant-ID"
  }
  

• Use the returned credentials above to set AZURE_CLIENT_ID(appId), AZURE_CLIENT_SECRET(password) and AZURE_TENANT_ID(tenant) environment variables. The following example shows a way to do this in Powershell:

  $Env:AZURE_CLIENT_ID="generated-app-ID"
  $Env:AZURE_CLIENT_SECRET="random-password"
  $Env:AZURE_TENANT_ID="tenant-ID"
  

• Grant the above mentioned application authorization to perform secret operations on the Key Vault:

  az keyvault set-policy --name <your-key-vault-name> --spn $AZURE_CLIENT_ID --secret-permissions backup delete get list set
  

  --secret-permissions: Accepted values: backup, delete, get, list, purge, recover, restore, set

• Use the above mentioned Key Vault name to retrieve details of your Vault which also contains your Key Vault URL:

  az keyvault show --name <your-key-vault-name> 
  

Create SecretClient

Once you've populated the AZURE_CLIENT_ID, AZURE_CLIENT_SECRET and AZURE_TENANT_ID environment variables and replaced your-vault-url with the above returned URI, you can create the SecretClient:

// Create a new secret client using the default credential from Azure.Identity using environment variables previously set,
// including AZURE_CLIENT_ID, AZURE_CLIENT_SECRET, and AZURE_TENANT_ID.
var client = new SecretClient(vaultUri: new Uri(keyVaultUrl), credential: new DefaultAzureCredential());

// Create a new secret using the secret client.
KeyVaultSecret secret = client.SetSecret("secret-name", "secret-value");

// Retrieve a secret using the secret client.
secret = client.GetSecret("secret-name");

Key concepts

KeyVaultSecret

A KeyVaultSecret is the fundamental resource within Azure Key Vault. From a developer's perspective, Key Vault APIs accept and return secret values as strings.

SecretClient

A SecretClient provides both synchronous and asynchronous operations in the SDK allowing for selection of a client based on an application's use case. Once you've initialized a SecretClient, you can interact with secrets in Key Vault.

Examples

The Azure.Security.KeyVault.Secrets package supports synchronous and asynchronous APIs.

The following section provides several code snippets using the above created client, covering some of the most common Azure Key Vault secret service related tasks:

Async examples

• Create a secret
• Retrieve a secret
• Update an existing secret
• Delete a secret
• Delete and purge a secret
• List Secrets

Sync examples

• Create a secret synchronously
• Delete a secret synchronously

Create a secret

SetSecretAsync creates a KeyVaultSecret to be stored in the Azure Key Vault. If a secret with the same name already exists, then a new version of the secret is created.

KeyVaultSecret secret = await client.SetSecretAsync("secret-name", "secret-value");

Console.WriteLine(secret.Name);
Console.WriteLine(secret.Value);
Console.WriteLine(secret.Properties.Version);
Console.WriteLine(secret.Properties.Enabled);

Retrieve a secret

GetSecretAsync retrieves a secret previously stored in the Key Vault.

KeyVaultSecret secret = await client.GetSecretAsync("secret-name");

Console.WriteLine(secret.Name);
Console.WriteLine(secret.Value);

Update an existing secret

UpdateSecretPropertiesAsync updates a secret previously stored in the Key Vault. Only the attributes of the secret are updated. To update the value, call SecretClient.SetSecretAsync on a secret with the same name.

KeyVaultSecret secret = await client.GetSecretAsync("secret-name");

// Clients may specify the content type of a secret to assist in interpreting the secret data when it's retrieved.
secret.Properties.ContentType = "text/plain";

// You can specify additional application-specific metadata in the form of tags.
secret.Properties.Tags["foo"] = "updated tag";

SecretProperties updatedSecretProperties = await client.UpdateSecretPropertiesAsync(secret.Properties);

Console.WriteLine(updatedSecretProperties.Name);
Console.WriteLine(updatedSecretProperties.Version);
Console.WriteLine(updatedSecretProperties.ContentType);

Delete a secret

StartDeleteSecretAsync starts a long-running operation to delete a secret previously stored in the Key Vault. You can retrieve the secret immediately without waiting for the operation to complete. When soft-delete is not enabled for the Key Vault, this operation permanently deletes the secret.

DeleteSecretOperation operation = await client.StartDeleteSecretAsync("secret-name");

DeletedSecret secret = operation.Value;
Console.WriteLine(secret.Name);
Console.WriteLine(secret.Value);

Delete and purge a secret

You will need to wait for the long-running operation to complete before trying to purge or recover the secret.

DeleteSecretOperation operation = await client.StartDeleteSecretAsync("secret-name");

// You only need to wait for completion if you want to purge or recover the secret.
await operation.WaitForCompletionAsync();

DeletedSecret secret = operation.Value;
await client.PurgeDeletedSecretAsync(secret.Name);

List secrets

This example lists all the secrets in the specified Key Vault. The value is not returned when listing all secrets. You will need to call SecretClient.GetSecretAsync to retrieve the value.

AsyncPageable<SecretProperties> allSecrets = client.GetPropertiesOfSecretsAsync();

await foreach (SecretProperties secretProperties in allSecrets)
{
    Console.WriteLine(secretProperties.Name);
}

Create a secret synchronously

Synchronous APIs are identical to their asynchronous counterparts, but without the typical "Async" suffix for asynchronous methods.

This example creates a secret in the Key Vault with the specified optional arguments.

KeyVaultSecret secret = client.SetSecret("secret-name", "secret-value");

Console.WriteLine(secret.Name);
Console.WriteLine(secret.Value);

Delete a secret synchronously

When deleting a secret synchronously before you purge it, you need to call UpdateStatus on the returned operation periodically. You could do this in a loop as shown in the example, or periodically within other operations in your program.

DeleteSecretOperation operation = client.StartDeleteSecret("secret-name");

// You only need to wait for completion if you want to purge or recover the secret.
while (!operation.HasCompleted)
{
    Thread.Sleep(2000);

    operation.UpdateStatus();
}

DeletedSecret secret = operation.Value;
client.PurgeDeletedSecret(secret.Name);

Troubleshooting

General

When you interact with the Azure Key Vault secret client library using the .NET SDK, errors returned by the service correspond to the same HTTP status codes returned for REST API requests.

For example, if you try to retrieve a secret that doesn't exist in your Key Vault, a 404 error is returned, indicating Not Found.

try
{
    KeyVaultSecret secret = await client.GetSecretAsync("some_secret");
}
catch (RequestFailedException ex)
{
    Console.WriteLine(ex.ToString());
}

You will notice that additional information is logged, like the Client Request ID of the operation.

Message: 
    Azure.RequestFailedException : Service request failed.
    Status: 404 (Not Found) 
Content:
    {"error":{"code":"SecretNotFound","message":"Secret not found: some_secret"}}
    
Headers:
    Cache-Control: no-cache
    Pragma: no-cache
    Server: Microsoft-IIS/10.0
    x-ms-keyvault-region: westus
    x-ms-request-id: 625f870e-10ea-41e5-8380-282e5cf768f2
    x-ms-keyvault-service-version: 1.1.0.866
    x-ms-keyvault-network-info: addr=131.107.174.199;act_addr_fam=InterNetwork;
    X-AspNet-Version: 4.0.30319
    X-Powered-By: ASP.NET
    Strict-Transport-Security: max-age=31536000;includeSubDomains
    X-Content-Type-Options: nosniff
    Date: Tue, 18 Jun 2019 16:02:11 GMT
    Content-Length: 75
    Content-Type: application/json; charset=utf-8
    Expires: -1

Next steps

Several Key Vault Secrets client library samples are available to you in this GitHub repository. These samples provide example code for additional scenarios commonly encountered while working with Key Vault:

• HelloWorld.cs and HelloWorldAsync.cs - for working with Azure Key Vault, including:

  • Create a secret
  • Get an existing secret
  • Update an existing secret
  • Delete secret

• BackupAndRestore.cs and BackupAndRestoreAsync.cs - Contains the code snippets working with Key Vault secrets, including:

  • Backup and recover a secret

• GetSecrets.cs and GetSecretsAsync.cs - Example code for working with Key Vault secrets, including:

  • Create secrets
  • List all secrets in the Key Vault
  • Update secrets in the Key Vault
  • List versions of a specified secret
  • Delete secrets from the Key Vault
  • List deleted secrets in the Key Vault

Additional Documentation

• For more extensive documentation on Azure Key Vault, see the API reference documentation.
• For Keys client library see Keys client library.
• For Certificates client library see Certificates client library.

Contributing

This project welcomes contributions and suggestions. Most contributions require you to agree to a Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us the rights to use your contribution. For details, visit https://cla.microsoft.com.

When you submit a pull request, a CLA-bot will automatically determine whether you need to provide a CLA and decorate the PR appropriately (e.g., label, comment). Simply follow the instructions provided by the bot. You will only need to do this once across all repos using our CLA.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact opencode@microsoft.com with any additional questions or comments.