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Azure Cache for Redis: Microsoft Entra ID with redis client library

Table of contents

Prerequisites

  • Configuration of Role and Role Assignments is required before using the sample code in this document.
  • Dependency requirements:

Samples guidance

Authenticate with Microsoft Entra ID - Hello World This sample is recommended for users getting started to use Microsoft Entra authentication with Azure Cache for Redis.

Authenticate with Microsoft Entra ID - Handle Re-Authentication This sample is recommended to users looking to build long-running applications that would like to handle re-authenticating with Microsoft Entra ID upon token expiry.

Authenticate with Microsoft Entra ID: Hello world

This sample is intended to assist in authenticating with Microsoft Entra ID via the redis client library. It focuses on displaying the logic required to fetch a Microsoft Entra access token and to use it as password when setting up the redis instance.

Migration guidance

When migrating your existing application code, you need to replace the password input with the Microsoft Entra token. Integrate the logic in your application code to fetch a Microsoft Entra access token via the azure-identity library as shown below and replace it with the password configuring/retrieving logic in your application code.

import redis
import base64
import json
from azure.identity import DefaultAzureCredential

scope = "https://redis.azure.com/.default"  # The current scope is for public preview and may change for GA release.
host = ""  # Required
port = 6380  # Required

def extract_username_from_token(token):
    parts = token.split('.')
    base64_str = parts[1]

    if len(base64_str) % 4 == 2:
        base64_str += "=="
    elif len(base64_str) % 4 == 3:
        base64_str += "="

    json_bytes = base64.b64decode(base64_str)
    json_str = json_bytes.decode('utf-8')
    jwt = json.loads(json_str)

    return jwt['oid']

def hello_world():
    cred = DefaultAzureCredential()
    token = cred.get_token(scope)
    user_name = extract_username_from_token(token.token)
    r = redis.Redis(host=host,
                    port=port,
                    ssl=True,    # ssl connection is required.
                    username=user_name,
                    password=token.token,
                    decode_responses=True)
    r.set("Az:key1", "value1")
    t = r.get("Az:key1")
    print(t)

if __name__ == '__main__':
    hello_world()
Supported Token Credentials for Microsoft Entra Authentication

Note: The samples in this doc use the azure-identity library's DefaultAzureCredential to fetch a Microsoft Entra access token. The other supported TokenCredential implementations that can be used from azure-identity are as follows:

Authenticate with Microsoft Entra ID: Handle re-authentication

This sample is intended to assist in authenticating with Microsoft Entra ID via the redis client library. It focuses on displaying the logic required to fetch a Microsoft Entra access token and to use it as password when setting up the redis instance. It also shows how to recreate and authenticate the redis instance when its connection is broken in error/exception scenarios.

Migration guidance

When migrating your existing application code, you need to replace the password input with the Microsoft Entra token. Integrate the logic in your application code to fetch a Microsoft Entra access token via the azure-identity library as shown below and replace it with the password configuring/retrieving logic in your application code.

import time
import logging
import redis
import base64
import json
from azure.identity import DefaultAzureCredential

scope = "https://redis.azure.com/.default"  # The current scope is for public preview and may change for GA release.
host = ""  # Required
port = 6380  # Required

def extract_username_from_token(token):
    parts = token.split('.')
    base64_str = parts[1]

    if len(base64_str) % 4 == 2:
        base64_str += "=="
    elif len(base64_str) % 4 == 3:
        base64_str += "="

    json_bytes = base64.b64decode(base64_str)
    json_str = json_bytes.decode('utf-8')
    jwt = json.loads(json_str)

    return jwt['oid']

def re_authentication():
    _LOGGER = logging.getLogger(__name__)
    cred = DefaultAzureCredential()
    token = cred.get_token(scope)
    user_name = extract_username_from_token(token.token)
    r = redis.Redis(host=host,
                    port=port,
                    ssl=True,   # ssl connection is required.
                    username=user_name,
                    password=token.token,
                    decode_responses=True)
    max_retry = 3
    for index in range(max_retry):
        try:
            if _need_refreshing(token):
                _LOGGER.info("Refreshing token...")
                tmp_token = cred.get_token(scope)
                if tmp_token:
                    token = tmp_token
                r.execute_command("AUTH", user_name, token.token)
            r.set("Az:key1", "value1")
            t = r.get("Az:key1")
            print(t)
            break
        except redis.ConnectionError:
            _LOGGER.info("Connection lost. Reconnecting.")
            token = cred.get_token(scope)
            r = redis.Redis(host=host,
                            port=port,
                            ssl=True,   # ssl connection is required.
                            username=user_name,
                            password=token.token,
                            decode_responses=True)
        except Exception:
            _LOGGER.info("Unknown failures.")
            break


def _need_refreshing(token, refresh_offset=300):
    return not token or token.expires_on - time.time() < refresh_offset

if __name__ == '__main__':
    re_authentication()

Troubleshooting

Invalid Username Password Pair Error

In this error scenario, the username provided and the access token used as password are not compatible. To mitigate this error, navigate to your Azure Cache for Redis resource in the Azure portal. Confirm that:

  • In Data Access Configuration, you've assigned the required role to your user/service principal identity.
  • Under Authentication -> Microsoft Entra Authentication category the Enable Microsoft Entra Authentication box is selected. If not, select it and select the Save button.
Permissions not granted / NOPERM Error

In this error scenario, the authentication was successful, but your registered user/service principal is not granted the RBAC permission to perform the action. To mitigate this error, navigate to your Azure Cache for Redis resource in the Azure portal. Confirm that:

  • In Data Access Configuration, you've assigned the appropriate role (Owner, Contributor, Reader) to your user/service principal identity.
  • In the event you're using a custom role, ensure the permissions granted under your custom role include the one required for your target action.
Managed Identity not working from Local Development Machine

Managed identity does not work from a local development machine. To use managed identity, your code must be running in an Azure VM (or another type of resource in Azure). To run locally with Entra ID authentication, you'll need to use a service principal or user account. This is a common source of confusion, so ensure that when developing locally, you configure your application to use a service principal or user credentials for authentication.