Add EntraID authentication support for Azure Managed Redis

[vchomakov]

Add EntraID Authentication Support for Azure Managed Redis

Overview

Implements comprehensive EntraID (Azure Active Directory) authentication for Azure Managed Redis, enabling OAuth-based authentication with automatic token management and graceful fallback to standard Redis authentication.

Features Added

Authentication Providers

• Service Principal - Application-based authentication (client ID, secret, tenant)
• Managed Identity - Both system-assigned and user-assigned identities
• Default Azure Credential - Automatic credential discovery for Azure environments

Key Capabilities

• Automatic token renewal - Background token refresh with redis-entraid
• Graceful fallback - Falls back to standard Redis auth when EntraID not configured
• Backward compatibility - Existing Redis configurations continue to work unchanged
• Enterprise ready - Designed for Azure Managed Redis tier

Technical Implementation

Core Changes

• Integrated redis-entraid package for OAuth token management
• Added credential provider factory with multiple auth flows

Configuration

# Authentication flow selection (required)
REDIS_ENTRAID_AUTH_FLOW=service_principal

# Service Principal Authentication
REDIS_ENTRAID_CLIENT_ID=your-client-id
REDIS_ENTRAID_CLIENT_SECRET=your-client-secret
REDIS_ENTRAID_TENANT_ID=your-tenant-id

# Managed Identity Authentication  
REDIS_ENTRAID_AUTH_FLOW=managed_identity
REDIS_ENTRAID_IDENTITY_TYPE=system_assigned
# or
REDIS_ENTRAID_IDENTITY_TYPE=user_assigned
REDIS_ENTRAID_USER_ASSIGNED_CLIENT_ID=your-identity-client-id

# Default Azure Credential
REDIS_ENTRAID_AUTH_FLOW=default_credential
REDIS_ENTRAID_SCOPES=https://redis.azure.com/.default

[bobymicroby]

LGTM