Add Microsoft Entra ID authentication methods to the MS SQL family destinations (SQL Server, Synapse, Fabric)

[sdebruyn]

Feature description

Add Microsoft Entra ID authentication to the mssql, synapse, and fabric destinations, covering both driver-native methods and token methods where dlt acquires and injects an access token.

Use case

The MS SQL family destinations authenticate with SQL Server logins (username and password). Many Azure users, and all Fabric Warehouse users, authenticate with Microsoft Entra ID instead. Fabric Warehouse does not accept SQL logins at all, so without Entra ID support the destination cannot connect. Service principal, Azure CLI, environment, and managed-identity authentication are also needed for unattended/CI runs and for setups where no interactive login is available.

Proposed solution

Add an authentication setting that selects one of:

• driver-native methods handled by the ODBC driver: ActiveDirectoryServicePrincipal, ActiveDirectoryPassword, ActiveDirectoryIntegrated, ActiveDirectoryInteractive;
• token methods where dlt uses azure-identity to acquire an access token and injects it through attrs_before, so they work cross-platform: cli, environment, interactive, devicecode, managedidentity, and auto/default (DefaultAzureCredential).

For Fabric, default to ActiveDirectoryServicePrincipal and fall back to DefaultAzureCredential when no service principal secret is configured.

Related issues

N/A

[sdebruyn]

This is available now as a maintained fork package on PyPI: https://pypi.org/project/dlt-fabric/.

It adds Microsoft Entra ID authentication (Azure CLI, service principal, managed identity, and the other azure-identity methods) for the mssql, synapse, and fabric destinations, packaged on top of the latest dlt release (currently 1.28.1). The change is proposed upstream in #4140.

The fork tracks dlt's releases and stays maintained until the upstream PRs (#4140, #4141, #4142, #4147) are merged, after which it is no longer needed. Install dlt-fabric in place of dlt (pip install dlt-fabric / uv add dlt-fabric); the import stays import dlt.