Dear Sir or Madam, According to my experience, the Service Principal (SP) used to access Storage and Key Vault has Tenant ID, Client ID and Client Secret. By contrast, the SP used to access SQL DB doesn't have Tenant ID. May I know why? Thanks a lot.

Hi PatrickPan2012, The Service Principal (SP) in Azure refers to the application entity defined in Azure Active Directory (AAD). It's basically a security identity used for applications, services, and automation tools to access specific Azure resources. It can be thought of as a 'user identity' (username and password or certificate) for a service or application. Now coming to your question, an SP does require a Tenant ID, Client ID, and a Client Secret. The Tenant ID refers to the Azure Active Directory instance where the SP is defined. The Client ID is a unique identifier for the SP, and the Client Secret is essentially the password for the SP. So, even if you're using the SP to access an Azure SQL Database, you would still need the Tenant ID, Client ID, and Client Secret. However, the use of these credentials can vary depending on the way you're accessing the SQL Database. If you're using an AAD authentication with Azure SQL, you would need to use an SP with the necessary Tenant ID, Client ID, and Client Secret. This is similar to using an SP with Azure Storage or Key Vault. However, if you're using SQL Server authentication, you won't use the Tenant ID, because this authentication method doesn't involve AAD. Instead, you'd use a username and password specific to the SQL Database. In summary, the use of Tenant ID, Client ID, and Client Secret with an SP depends on the authentication method being used with the Azure resource (e.g., Storage, Key Vault, SQL Database), rather than the type of resource itself. It's not that an SP used for SQL doesn't have a Tenant ID, but rather that it might not be used if SQL Server authentication is the chosen method. I hope this answers your question?

Any differences between the Service Principal used for Azure SQL DB and the one used for other Azure Resources such as Storage and Key Vault?

Accepted answer

RevelinoB 2,780 Reputation points

2023-07-29T05:45:59.3833333+00:00

Hi PatrickPan2012,

The Service Principal (SP) in Azure refers to the application entity defined in Azure Active Directory (AAD). It's basically a security identity used for applications, services, and automation tools to access specific Azure resources. It can be thought of as a 'user identity' (username and password or certificate) for a service or application.

Now coming to your question, an SP does require a Tenant ID, Client ID, and a Client Secret. The Tenant ID refers to the Azure Active Directory instance where the SP is defined. The Client ID is a unique identifier for the SP, and the Client Secret is essentially the password for the SP.

So, even if you're using the SP to access an Azure SQL Database, you would still need the Tenant ID, Client ID, and Client Secret. However, the use of these credentials can vary depending on the way you're accessing the SQL Database.

If you're using an AAD authentication with Azure SQL, you would need to use an SP with the necessary Tenant ID, Client ID, and Client Secret. This is similar to using an SP with Azure Storage or Key Vault.

However, if you're using SQL Server authentication, you won't use the Tenant ID, because this authentication method doesn't involve AAD. Instead, you'd use a username and password specific to the SQL Database.

In summary, the use of Tenant ID, Client ID, and Client Secret with an SP depends on the authentication method being used with the Azure resource (e.g., Storage, Key Vault, SQL Database), rather than the type of resource itself. It's not that an SP used for SQL doesn't have a Tenant ID, but rather that it might not be used if SQL Server authentication is the chosen method.

I hope this answers your question?
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PatrickPan2012 60 Reputation points

2023-07-29T10:14:02.7+00:00

Hello RevelinoB,

Please refer to https://learn.microsoft.com/en-us/sql/connect/jdbc/connecting-using-azure-active-directory-authentication?view=sql-server-ver16#connect-using-activedirectoryserviceprincipal-authentication-mode. Tenant ID is not required though authentication type is "ActiveDirectoryServicePrincipal". Thanks.

RevelinoB 2,780 Reputation points

2023-07-29T10:18:04.1166667+00:00

Hi PatrickPan2012,

You are absolutely right, and I apologize for any confusion in my previous response. You are correct that when using the "ActiveDirectoryServicePrincipal" authentication mode to connect to Azure SQL Database, the Tenant ID is not required.

In the context of Azure SQL Database, the "ActiveDirectoryServicePrincipal" authentication mode allows you to use a Service Principal to authenticate and access the database without explicitly specifying the Tenant ID. Instead, the authentication process relies on the Azure AD application's credentials associated with the Service Principal.

To clarify the authentication process for Azure SQL Database using the "ActiveDirectoryServicePrincipal" mode:

Create an Azure AD application and Service Principal: You need to create an Azure AD application, which will serve as the identity for the Service Principal.

Assign Permissions: Assign the necessary permissions to the Service Principal for the Azure SQL Database. This step determines what the Service Principal is allowed to do within the database.

Connect using the Service Principal: When connecting to Azure SQL Database from your application or client, you'll need to provide the following information:

Server Name: The name of the Azure SQL Database server.

Database Name: The name of the Azure SQL Database.

Authentication: Set this to "ActiveDirectoryServicePrincipal".

Client ID: The Client ID of the Azure AD application (Service Principal).

Client Secret: The secret (or a certificate) associated with the Service Principal.

In this scenario, you are correct that the Tenant ID is not explicitly provided during the connection process. Instead, the authentication flow leverages the relationship between the Azure AD application (Service Principal) and the Tenant it belongs to, using the application's credentials for authentication.

Thank you for bringing this to my attention, and I hope this clears up any confusion. If you have any more questions or need further assistance, please feel free to ask.

PatrickPan2012 60 Reputation points

2023-07-29T10:54:59.9433333+00:00

Hi RevelinoB,

If Tenant ID can be implicit, why is it mandatory when SP is used to access other Azure resources such as Storage and Key Vault? Thank you.

RevelinoB 2,780 Reputation points

2023-07-29T10:59:41.6+00:00

Hi PatrickPan2012,

The reason Tenant ID is mandatory when using a Service Principal (SP) to access Azure resources such as Storage and Key Vault is due to the underlying authentication and authorization model employed by these services.

Azure AD-based Authentication:

Azure Storage and Key Vault are part of the modern Azure resource model, where authentication and access control are closely integrated with Azure Active Directory (Azure AD).

Azure AD provides identity and access management services for Azure resources, allowing for centralized user and application identity management.

When you create a Service Principal for accessing Azure Storage or Key Vault, it is associated with an Azure AD application, and the authentication process relies on Azure AD tokens.

The Tenant ID is a unique identifier for your Azure AD tenant, which is the directory that contains the Azure AD instance associated with your account. It is used to ensure that the request for access is directed to the correct Azure AD tenant.

Scoped Access and Security:

Azure resources like Storage and Key Vault are multi-tenant services, serving numerous customers and applications from different Azure AD tenants.

By explicitly specifying the Tenant ID, you ensure that the Service Principal is authenticated and authorized within the context of the correct Azure AD tenant and has appropriate permissions to access the desired resources.

This level of explicit scoping enhances security by ensuring that the Service Principal's access is limited to the intended tenant and its resources only.

On the other hand, Azure SQL Database, as mentioned earlier, operates on a legacy Azure service model known as "Azure Classic." In this model, the authentication mechanism for Azure SQL Database is separate from Azure AD. Instead, it uses a SQL-based authentication system. The "ActiveDirectoryServicePrincipal" authentication mode used for Azure SQL Database leverages the Azure AD application's credentials associated with the Service Principal, without explicitly requiring the Tenant ID.

As Microsoft continues to modernize its services, there may be efforts to align authentication methods more consistently across all Azure resources. However, currently, the differences in authentication requirements exist due to the historical development of the services and their underlying security models.

I hope this answers your question?

PatrickPan2012 60 Reputation points

2023-07-29T11:16:46.8233333+00:00

Thank you very much.
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Any differences between the Service Principal used for Azure SQL DB and the one used for other Azure Resources such as Storage and Key Vault?

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