Configure Authentication for Azure Event Hubs

Securely connecting to your Azure Event Hubs namespace is crucial for protecting your data. This guide walks you through the common authentication methods available.

Authentication Methods

Azure Event Hubs supports several authentication mechanisms, allowing you to choose the method that best fits your application's security requirements and deployment environment.

1. Connection Strings

Connection strings are the simplest way to authenticate. They contain the endpoint and shared access signature (SAS) keys required to connect. While convenient, they should be managed carefully as they grant broad access.

Obtaining a Connection String

Navigate to your Event Hubs namespace in the Azure portal.
In the left-hand menu, under "Settings", select "Shared access policies".
Choose an existing policy or create a new one. Ensure the policy has the necessary permissions (e.g., "Listen", "Send", "Manage").
Under the policy details, you will find "Primary connection string" and "Secondary connection string". Copy one of these.

Using a Connection String

You can use the connection string directly in your application code or configuration files.


// Example using Azure SDK for .NET
using Azure.Messaging.EventHubs;

string connectionString = "";
string eventHubName = "";

await using var producerClient = new EventHubProducerClient(connectionString, eventHubName);
// ... send messages

Note: Storing connection strings directly in code is not recommended for production environments. Consider using Azure Key Vault or environment variables.

2. Azure Active Directory (Azure AD) Authentication

Azure AD authentication offers a more secure and robust approach, leveraging managed identities or service principals. This eliminates the need to manage SAS keys directly.

Managed Identities

Managed identities are ideal when your application runs on Azure services like Azure App Service, Azure Functions, or Azure Kubernetes Service. Azure automatically manages the credentials.

Enable a system-assigned or user-assigned managed identity for your Azure resource.
Grant the managed identity appropriate roles (e.g., "Azure Event Hubs Data Sender", "Azure Event Hubs Data Receiver") on your Event Hubs namespace or specific hub.
Configure your application to use the managed identity for authentication.

Service Principals

Service principals are suitable for applications running outside of Azure or when you need fine-grained control over credentials.

Create an Azure AD application registration.
Create a client secret or certificate for the service principal.
Grant the service principal the necessary roles on your Event Hubs namespace.
Use the application ID, tenant ID, and client secret/certificate in your application's authentication configuration.

Using Azure AD Credentials


// Example using Azure SDK for Python with DefaultAzureCredential
from azure.identity import DefaultAzureCredential
from azure.eventhub import EventHubProducerClient

eventhub_namespace = ".servicebus.windows.net"
eventhub_name = ""

# DefaultAzureCredential will try to authenticate using environment variables,
# managed identity, or service principal configurations.
credential = DefaultAzureCredential()

producer = EventHubProducerClient(
    fully_qualified_namespace=eventhub_namespace,
    eventhub_name=eventhub_name,
    credential=credential
)
# ... send messages

Tip: For optimal security, always use the least privilege principle when assigning roles to your identities.

3. SAS Tokens

You can also generate and use Shared Access Signature (SAS) tokens programmatically. This is useful for scenarios where you need temporary access with specific permissions.

The Azure SDKs often provide utilities to help generate SAS tokens from your primary or secondary keys.

Choosing the Right Method

Consider the following when deciding on an authentication method:

Security: Azure AD authentication is generally more secure than connection strings.
Management: Managed identities simplify credential management on Azure.
Environment: Connection strings are easy for local development, while Azure AD is preferred for production.
Granularity: Azure AD allows for more granular role-based access control.

Warning: Never commit connection strings or service principal secrets directly into source control.

By properly configuring authentication, you ensure the integrity and confidentiality of your data flowing through Azure Event Hubs.