SignalR Service bindings for Azure Functions

This set of articles explains how to authenticate and send real-time messages to clients connected to Azure SignalR Service by using SignalR Service bindings in Azure Functions. Azure Functions runtime version 2.x and higher supports input and output bindings for SignalR Service.

{
    "version": "2.0",
    "extensionBundle": {
        "id": "Microsoft.Azure.Functions.ExtensionBundle",
        "version": "[4.0.0, 5.0.0)"
    }
}

<dependency>
    <groupId>com.microsoft.azure.functions</groupId>
    <artifactId>azure-functions-java-library-signalr</artifactId>
    <version>1.0.0</version>
</dependency>

Connections

You can use connection string or Microsoft Entra identity to connect to Azure SignalR Service.

Connection string

For instructions on how to retrieve the connection string for your Azure SignalR Service, see Connection strings in Azure SignalR Service

This connection string should be stored in an application setting with a name AzureSignalRConnectionString. You can customize the application setting name with the connectionStringSetting property of the binding configuration.

Identity-based connections

If you're using version 1.7.0 or higher, instead of using a connection string with a secret, you can have the app use an Microsoft Entra identity.

First of all, you should make sure your Microsoft Entra identity has role SignalR Service Owner.

Then you would define settings with a common prefix AzureSignalRConnectionString. You can customize prefix name with the connectionStringSetting property of the binding configuration.

In this mode, the settings include following items:

Multiple endpoints setting

You can also configure multiple endpoints and specify identity settings per endpoint.

In this case, prefix your settings with Azure__SignalR__Endpoints__{endpointName}. The {endpointName} is an arbitrary name assigned by you to associate a group of settings to a service endpoint. The prefix Azure__SignalR__Endpoints__{endpointName} can't be customized by connectionStringSetting property.

For more information about multiple endpoints, see Scale SignalR Service with multiple instances

For optimal security, your function app should use managed identities when connecting to the Azure SignalR service instead of using a connection string, which contains a shared secret key. For more information, see Authorize requests to Azure SignalR Service resources with Microsoft Entra managed identities.

Next steps

For details on how to configure and use SignalR Service and Azure Functions together, refer to Azure Functions development and configuration with Azure SignalR Service.

• Handle messages from SignalR Service (Trigger binding)
• Return the service endpoint URL and access token (Input binding)
• Send SignalR Service messages (Output binding)