Manage secrets for retail channels

Articolo
08/12/2022

This article explains how to manage secrets when you're using an extension with channels that require access to secrets. Extensions will not be able to deploy any custom certificates in Commerce scale unit or add thumbprints or secrets in web.config files. The recommended approach for managing secrets is to use the Azure Key Vault, as noted in this article.

Key Vault setup

The extension developer follows these development steps:
1. Create a test secret in Microsoft Azure Key Vault.
2. Configure the head-office client to connect to Key Vault.
3. On the Key Vault Parameters page (Head Office > Key Vault Parameters), specify an extension key name for the Key Vault secret. The same name must be used in the next step.
4. Use the GetUserDefinedSecretStringValueServiceRequest Commerce Runtime (CRT) application programming interface (API) to get the secret. Pass a unique secret name to identify the secret.
5. As part of the documentation of the extension setup, state the secret name that is referenced in the extension. We recommend that the extension developer use a namespace for the secret name, because this approach helps prevent conflicts with other extensions.
The IT pro or implementation partner follows these deployment and configuration steps:
1. Apply the extension to the customer environment. For details, see Apply updates to cloud environments.
2. Upload the desired secrets to Key Vault (or enter them). For details, see What is Azure Key Vault?
3. On the Key Vault Parameters page (Head Office > Key Vault Parameters), configure the head-office client to connect to Key Vault.
4. On the Key Vault Parameters page, specify the extension secret name for the Key Vault secret in the head-office client.

Consume the secret in the CRT extension

To consume the secret in the extension, add the following request and response.

Request/response	Parameters	Description
GetUserDefinedSecretStringValueServiceRequest	string secretName	The request class that is used to get user-defined secrets from Headquarters.
GetUserDefinedSecretStringValueServiceResponse	string SecretStringValue	The response class that is used to get user-defined secrets from Headquarters. The response returns a SecretStringValue value, and extensions can type-cast this value to X509Certificate2 or use it as string value.

To read the secret in the CRT extension, follow these steps.

Cache the key vault in memory in CRT/Retail Server

Whenever a call is made to read the Key Vault secret value in CRT, CRT calls Headquarters in real time to get the value. Headquarters then calls the key vault to get the value. Because multiples hops are involved in reading the value, the latency for the call is increased. Therefore, we recommend that you cache the Key Vault secret value in memory on the CRT/Retail Server side to help improve performance. If the value is often changed in Key Vault, you must decide the correct strategy for cache expiration, based on your scenario.

Create a new CRT extension project (C# class library project type). Use the sample templates from the Retail software development kit (SDK) (RetailSDK\SampleExtensions\CommerceRuntime).

In the CRT extension, you can create a new request/response, or you can add a pre-trigger or post-trigger for the existing CRT request, and then call it. In the following example, a trigger was added for SaveCartRequest. It calls GetUserDefinedSecretStringValueServiceRequest to read the secret by passing the secret key that is configured in Headquarters. You don't have to write custom code to read the secret from Headquarters. You can use the request and response to read the value.

public class CustomSaveCartTrigger : IRequestTrigger
{
    /// <summary>
    /// Gets the list of supported request types.
    /// </summary>
    public IEnumerable<Type> SupportedRequestTypes
    {
        get
        {
            return new[]{ typeof(SaveCartRequest) };
        }
    }

    /// <summary>
    /// Pre trigger code.
    /// </summary>
    /// <param name="request">The request.</param>
    public void OnExecuting(Request request)
    {
        ThrowIf.Null(request, "request");
        Type requestedType = request.GetType();
        if (requestedType == typeof(SaveCartRequest))
        {
            // Sample code to get the secret in string format.

            string result = null;

            GetUserDefinedSecretStringValueServiceRequest keyVaultRequest = new GetUserDefinedSecretStringValueServiceRequest("SecretName");
            GetUserDefinedSecretStringValueServiceResponse keyVaultResponse = request.RequestContext.Execute<GetUserDefinedSecretStringValueServiceResponse>(keyVaultRequest);
            result = keyVaultResponse.SecretStringValue;

             GetUserDefinedSecretCertificateServiceRequest getUserDefinedSecretCertificateServiceRequest = new GetUserDefinedSecretCertificateServiceRequest(profileId: null, secretName: "SecretName", thumbprint: null, expirationInterval: null);
             GetUserDefinedSecretCertificateServiceResponse getUserDefinedSecretCertificateServiceResponse = request.RequestContext.Execute<GetUserDefinedSecretCertificateServiceResponse>(getUserDefinedSecretCertificateServiceRequest);

            X509Certificate2 Certificate = getUserDefinedSecretCertificateServiceResponse.Certificate;

            // custom code to additional processing with secrets.
        }
    }

    /// <summary>
    /// Post trigger code.
    /// </summary>
    /// <param name="request">The request.</param>
    /// <param name="response">The response.</param>

    public void OnExecuted(Request request, Response response)
    {
    }
}

Build the CRT extension project.
Copy the output class library, and paste it into …\RetailServer\webroot\bin\Ext for manual testing.
In the CommerceRuntime.Ext.config file, update the extension composition section with the custom library information. Here is an example.
```
<add source="assembly" value="your custom library name" />
```

Credential rotation

When this approach is used for credential management, credential rotation is more streamlined. To update a secret, an IT administrator just has to update the secret in Key Vault. No change is required to the extension.

Offline support

Offline support for credentials requires that the extension code handle failover to offline when Key Vault credentials aren't available or accessible.