Connecting to Azure Data Lake Storage

Set AzureStorageAccount to your Azure Data Lake Storage account name.

Authenticating to Azure Data Lake Storage

You can authenticate to Azure Data Lake Storage via Access Key, Shared Access Signature (SAS), AzureAD user, Azure MSI, or Azure Service Principal.

Access Key

Set the following to authenticate with an Azure Access Key:

• AuthScheme: Set this to AccessKey.
• AzureAccessKey: Set this to the storage key associated with your Azure Data Lake Storage account.

Shared Access Signature (SAS)

Set the following to authenticate with an Shared Access Signature (SAS):

• AuthScheme: Set this to AzureStorageSAS.
• AzureSharedAccessSignature: Set this to the SAS associated with your Azure Blob Storage account.

Follow these steps to create a shared access signature using AzureSharedAccessSignature:

1. Sign into the Azure Portal with the credentials for your root account. (https://portal.azure.com/)
2. Click storage accounts and select the storage account you want to use.
3. Under settings, click Shared Access Signature.
4. Set the permissions.
5. Specify when you want the token to expire.
6. Click Generate SAS and copy the shared access signature it generates.
7. Set AzureSharedAccessSignature to the shared access signature from the previous step.

AzureAD User

AuthScheme must be set to AzureAD in all user account flows.

Desktop Applications

CData provides an embedded OAuth application that simplifies OAuth desktop Authentication. Alternatively, you can create a custom OAuth application. See Creating a Custom OAuth App for information about creating custom applications and reasons for doing so.

Get and Refresh the OAuth Access Token

After setting the following, you are ready to connect:

• InitiateOAuth: Set this to GETANDREFRESH. You can use InitiateOAuth to avoid repeating the OAuth exchange and manually setting the OAuthAccessToken.
• OAuthClientId (custom applications only): Set this to the client Id assigned when you registered your app.
• OAuthClientSecret (custom applications only): Set this to the client secret assigned when you registered your app.
• CallbackURL (custom application only): Set this to the redirect URI defined when you registered your app. For example: http://localhost:33333

When you connect, the driver opens the Microsoft identity platform's OAuth endpoint in your default browser. Log in and grant permissions to the application. The driver then completes the OAuth process:

1. The driver obtains an access token from the Microsoft identity platform and uses it to request data.
2. The OAuth values are saved in the location specified in OAuthSettingsLocation, to be persisted across connections.

The driver refreshes the access token automatically when it expires.

Web Applications

When connecting via a Web application, you need to register a custom OAuth app with Azure Active Directory. You can then use the driver to get and manage the OAuth token values. See Creating a Custom OAuth App for more information.

Get an OAuth Access Token

Set the following connection properties to obtain the OAuthAccessToken:

• OAuthClientId: Set this to the client Id in your app settings.
• OAuthClientSecret: Set this to the client secret in your app settings.

Then call stored procedures to complete the OAuth exchange:

1. Call the GetOAuthAuthorizationURL stored procedure. Set the CallbackURL input to the Redirect URI you specified in your app settings. The stored procedure returns the URL to the OAuth endpoint.

2. Navigate to the URL that the stored procedure returned in Step 1. Log in, and authorize the web application. After authenticating, the browser redirects you to the redirect URI. There will be a parameter called code appended to the redirect URI. Note the value of this parameter.
3. Call the GetOAuthAccessToken stored procedure. Set the AuthMode input to WEB. Set the Verifier input to the code parameter in the query string of the redirect URI.

After you have obtained the access and refresh tokens, you can connect to data and refresh the OAuth access token either automatically or manually.

Automatic Refresh of the OAuth Access Token

To have the driver automatically refresh the OAuth access token, set the following on the first data connection.

• InitiateOAuth: Set this to REFRESH.
• OAuthClientId: Set this to the client Id in your app settings.
• OAuthClientSecret: Set this to the client secret in your app settings.
• OAuthAccessToken: Set this to the access token returned by GetOAuthAccessToken.
• OAuthRefreshToken: Set this to the refresh token returned by GetOAuthAccessToken.
• OAuthSettingsLocation: Set this to the location where you want the driver to save the OAuth values, which persist across connections.

Manual Refresh of the OAuth Access Token

The only value needed to manually refresh the OAuth access token when connecting to data is the OAuth refresh token. Use the RefreshOAuthAccessToken stored procedure to manually refresh the OAuthAccessToken after the ExpiresIn parameter value returned by GetOAuthAccessToken has elapsed, then set the following connection properties:

• OAuthClientId: Set this to the client Id in your app settings.
• OAuthClientSecret: Set this to the client secret in your app settings.

Then call RefreshOAuthAccessToken with OAuthRefreshToken set to the OAuth refresh token returned by GetOAuthAccessToken. After the new tokens have been retrieved, open a new connection by setting the OAuthAccessToken property to the value returned by RefreshOAuthAccessToken.

Finally, store the OAuth refresh token so that you can use it to manually refresh the OAuth access token after it has expired.

Headless Machines

To configure the driver, use OAuth with a user account on a headless machine. You need to authenticate on another device that has an internet browser.

1. Choose one of two options:
   • Option 1: Obtain the OAuthVerifier value as described in "Obtain and Exchange a Verifier Code" below.
   • Option 2: Install the driver on a machine with an internet browser and transfer the OAuth authentication values after you authenticate through the usual browser-based flow.
2. Then configure the driver to automatically refresh the access token on the headless machine.

Option 1: Obtain and Exchange a Verifier Code

To obtain a verifier code, you must authenticate at the OAuth authorization URL.

Follow the steps below to authenticate from the machine with an internet browser and obtain the OAuthVerifier connection property.

1. Choose one of these options:
   • If you are using the Embedded OAuth Application, call the GetOAuthAuthorizationURL stored procedure. Open the URL returned by the stored procedure in a browser.
   • If you are using a custom OAuth application, set the following properties:
     • InitiateOAuth: Set to OFF.
     • OAuthClientId: Set to the client Id assigned when you registered your application.
     • OAuthClientSecret: Set to the client secret assigned when you registered your application.
     Then call the GetOAuthAuthorizationURL stored procedure with the appropriate CallbackURL. Open the URL returned by the stored procedure in a browser.
2. Log in and grant permissions to the driver. You are then redirected to the redirect URI.

There will be a parameter called code appended to the redirect URI. Note the value of this parameter. Later you will set this in the OAuthVerifier connection property.

Next, you need to exchange the OAuth verifier code for OAuth refresh and access tokens.

On the headless machine, set the following connection properties to obtain the OAuth authentication values:

• InitiateOAuth: Set this to REFRESH.
• OAuthVerifier: Set this to the noted verifier code (the value of the code parameter in the redirect URI).
• OAuthClientId: (custom applications only) Set this to the client Id in your custom OAuth application settings.
• OAuthClientSecret: (custom applications only) Set this to the client secret in the custom OAuth application settings.
• OAuthSettingsLocation: Set this to persist the encrypted OAuth authentication values to the specified location.

Test the connection to generate the OAuth settings file, then re-set the following properties to connect:

• InitiateOAuth: Set this to REFRESH.
• OAuthClientId: (custom applications only) Set this to the client Id assigned when you registered your application.
• OAuthClientSecret: (custom applications only) Set this to the client secret assigned when you registered your application.
• OAuthSettingsLocation: Set this to the location containing the encrypted OAuth authentication values. Make sure this location gives read and write permissions to the driver to enable the automatic refreshing of the access token.

Option 2: Transfer OAuth Settings

Prior to connecting on a headless machine, you need to install and create a connection with the driver on a device that supports an internet browser. Set the connection properties as described in "Desktop Applications" above.

After completing the instructions in "Desktop Applications", the resulting authentication values are encrypted and written to the location specified by OAuthSettingsLocation. The default filename is OAuthSettings.txt.

Test the connection to generate the OAuth settings file, then copy the OAuth settings file to your headless machine.

On the headless machine, set the following connection properties to connect to data:

• InitiateOAuth: Set this to REFRESH.
• OAuthClientId: (custom applications only) Set this to the client Id assigned when you registered your application.
• OAuthClientSecret: (custom applications only) Set this to the client secret assigned when you registered your application.
• OAuthSettingsLocation: Set this to the location of the OAuth settings file you copied from the machine with the browser. Make sure this location gives read and write permissions to the driver to enable the automatic refreshing of the access token.

Azure Service Principal

The authentication as an Azure Service Principal is handled via the OAuth Client Credentials flow. It does not involve direct user authentication. Instead, credentials are created for just the application itself. All tasks taken by the app are done without a default user context, but based on the assigned roles. The application access to the resources is controlled through the assigned roles' permissions.

Create an AzureAD App and an Azure Service Principal

When authenticating using an Azure Service Principal, you must create and register an Azure AD application with an Azure AD tenant. See Creating a Custom OAuth Application for more details.

In your App Registration in portal.azure.com, navigate to API Permissions and select the Microsoft Graph permissions. There are two distinct sets of permissions: Delegated permissions and Application permissions. The permissions used during client credential authentication are under Application Permissions.

Assign a role to the application

To access resources in your subscription, you must assign a role to the application.

1. Open the Subscriptions page by searching and selecting the Subscriptions service from the search bar.
2. Select the subscription to assign the application to.
3. Open the Access control (IAM) and select Add > Add role assignment to open the Add role assignment page.
4. Select Owner as the role to assign to your created Azure AD app.

Complete the Authentication Choose whether to use a client secret or a certificate and follow the relevant steps below.

Client Secret

Set these connection properties:

• AuthScheme: AzureServicePrincipal to use a client secret.
• InitiateOAuth: GETANDREFRESH. You can use InitiateOAuth to avoid repeating the OAuth exchange and manually setting the OAuthAccessToken.
• AzureTenant: The tenant you want to connect to.
• OAuthClientId: The client Id in your application settings.
• OAuthClientSecret: The client secret in your application settings.

Certificate

Set these connection properties:

• AuthScheme: AzureServicePrincipalCert to use a certificate.
• InitiateOAuth: GETANDREFRESH. You can use InitiateOAuth to avoid repeating the OAuth exchange and manually setting the OAuthAccessToken.
• AzureTenant: The tenant you want to connect to.
• OAuthJWTCert: The JWT Certificate store.
• OAuthJWTCertType: The type of the certificate store specified by OAuthJWTCert.

You are now ready to connect. Authentication with client credentials takes place automatically like any other connection, except there is no window opened prompting the user. Because there is no user context, there is no need for a browser popup. Connections take place and are handled internally.

Azure MSI

If you are connecting from an Azure VM with permissions for Azure Data Lake Storage, set AuthScheme to AzureMSI.

Azure Service Principal

If you would like to authenticate with a service principal instead of a client secret, it is also possible to authenticate with a client certificate. Set the following to authenticate:

• InitiateOAuth: Set this to GETANDREFRESH. You can use InitiateOAuth to avoid repeating the OAuth exchange and manually setting the OAuthAccessToken.
• AuthScheme: Set this to AzureServicePrincipal.
• AzureTenant: Set this to the tenant you wish to connect to.
• OAuthGrantType: Set this to CLIENT.
• OAuthClientId: Set this to the Client Id in your app settings.
• OAuthJWTCert: Set this to the JWT Certificate store.
• OAuthJWTCertType: Set this to the type of the certificate store specified by OAuthJWTCert.