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Showing content from https://learn.microsoft.com/azure/azure-functions/functions-bindings-rabbitmq-trigger below:

RabbitMQ trigger for Azure Functions

Use the RabbitMQ trigger to respond to messages from a RabbitMQ queue.

For information on setup and configuration details, see the overview.

You can create a C# function by using one of the following C# modes:

• Isolated worker model: Compiled C# function that runs in a worker process that's isolated from the runtime. An isolated worker process is required to support C# functions running on long-term support (LTS) and non-LTS versions for .NET and the .NET Framework.
• In-process model: Compiled C# function that runs in the same process as the Azure Functions runtime.
• C# script: Used primarily when you create C# functions in the Azure portal.

• Isolated worker model
• In-process model

[Function(nameof(RabbitMQFunction))]
[RabbitMQOutput(QueueName = "destinationQueue", ConnectionStringSetting = "RabbitMQConnection")]
public static string Run([RabbitMQTrigger("queue", ConnectionStringSetting = "RabbitMQConnection")] string item,
    FunctionContext context)
{
    var logger = context.GetLogger(nameof(RabbitMQFunction));

    logger.LogInformation(item);

    var message = $"Output message created at {DateTime.Now}";
    return message;
}

The following example shows a C# function that reads and logs the RabbitMQ message as a RabbitMQ Event:

[FunctionName("RabbitMQTriggerCSharp")]
public static void RabbitMQTrigger_BasicDeliverEventArgs(
    [RabbitMQTrigger("queue", ConnectionStringSetting = "rabbitMQConnectionAppSetting")] BasicDeliverEventArgs args,
    ILogger logger
    )
{
    logger.LogInformation($"C# RabbitMQ queue trigger function processed message: {Encoding.UTF8.GetString(args.Body)}");
}

The following example shows how to read the message as a POCO.

namespace Company.Function
{
    public class TestClass
    {
        public string x { get; set; }
    }

    public class RabbitMQTriggerCSharp{
        [FunctionName("RabbitMQTriggerCSharp")]
        public static void RabbitMQTrigger_BasicDeliverEventArgs(
            [RabbitMQTrigger("queue", ConnectionStringSetting = "rabbitMQConnectionAppSetting")] TestClass pocObj,
            ILogger logger
            )
        {
            logger.LogInformation($"C# RabbitMQ queue trigger function processed message: {pocObj}");
        }
    }
}

Like with JSON objects, an error will occur if the message isn't properly formatted as a C# object. If it is, it's then bound to the variable pocObj, which can be used for what whatever it's needed for.

The following Java function uses the @RabbitMQTrigger annotation from the Java RabbitMQ types to describe the configuration for a RabbitMQ queue trigger. The function grabs the message placed on the queue and adds it to the logs.

@FunctionName("RabbitMQTriggerExample")
public void run(
    @RabbitMQTrigger(connectionStringSetting = "rabbitMQConnectionAppSetting", queueName = "queue") String input,
    final ExecutionContext context)
{
    context.getLogger().info("Java HTTP trigger processed a request." + input);
}

The following example shows a RabbitMQ trigger binding in a function.json file and a JavaScript function that uses the binding. The function reads and logs a RabbitMQ message.

Here's the binding data in the function.json file:

{​​
    "bindings": [
        {​​
            "name": "myQueueItem",
            "type": "rabbitMQTrigger",
            "direction": "in",
            "queueName": "queue",
            "connectionStringSetting": "rabbitMQConnectionAppSetting"
        }​​
    ]
}​​

Here's the JavaScript script code:

module.exports = async function (context, myQueueItem) {​​
    context.log('JavaScript RabbitMQ trigger function processed work item', myQueueItem);
}​​;

The following example demonstrates how to read a RabbitMQ queue message via a trigger.

A RabbitMQ binding is defined in function.json where type is set to RabbitMQTrigger.

{​​
    "scriptFile": "__init__.py",
    "bindings": [
        {​​
            "name": "myQueueItem",
            "type": "rabbitMQTrigger",
            "direction": "in",
            "queueName": "queue",
            "connectionStringSetting": "rabbitMQConnectionAppSetting"
        }​​
    ]
}​​

import logging
import azure.functions as func

def main(myQueueItem) -> None:
    logging.info('Python RabbitMQ trigger function processed a queue item: %s', myQueueItem)

Both in-process and isolated worker process C# libraries use the attribute to define the function. C# script instead uses a function.json configuration file.

The attribute's constructor takes the following parameters:

• Isolated worker model
• In-process model

In C# class libraries, use the RabbitMQTrigger attribute.

Here's a RabbitMQTrigger attribute in a method signature for an isolated worker process library:

[Function(nameof(RabbitMQFunction))]
[RabbitMQOutput(QueueName = "destinationQueue", ConnectionStringSetting = "RabbitMQConnection")]
public static string Run([RabbitMQTrigger("queue", ConnectionStringSetting = "RabbitMQConnection")] string item,
    FunctionContext context)
{

In C# class libraries, use the RabbitMQTrigger attribute.

Here's a RabbitMQTrigger attribute in a method signature for an in-process library:

[FunctionName("RabbitMQTest")]
public static void RabbitMQTest([RabbitMQTrigger("queue")] string message, ILogger log)
{
    ...
}

The RabbitMQTrigger annotation allows you to create a function that runs when a RabbitMQ message is created.

The annotation supports the following configuration options:

The following table explains the binding configuration properties that you set in the function.json file.

When you're developing locally, add your application settings in the local.settings.json file in the Values collection.

See the Example section for complete examples.

Important

The RabbitMQ binding doesn't support Microsoft Entra authentication and managed identities. You can use Azure Key Vault to centrally managed your RabbitMQ connection strings. To learn more, see Manage Connections.

The parameter type supported by the RabbitMQ trigger depends on the C# modality used.

• Isolated worker model
• In-process model

The RabbitMQ bindings currently support only string and serializable object types when running in an isolated process.

The default message type is RabbitMQ Event, and the Body property of the RabbitMQ Event can be read as the types listed below:

• An object serializable as JSON - The message is delivered as a valid JSON string.
• string
• byte[]
• POCO - The message is formatted as a C# object. For complete code, see C# example.

For a complete example, see C# example.

Refer to Java annotations.

The queue message is available via context.bindings.<NAME> where <NAME> matches the name defined in function.json. If the payload is JSON, the value is deserialized into an object.

Refer to the Python example.

Dead letter queues and exchanges can't be controlled or configured from the RabbitMQ trigger. To use dead letter queues, pre-configure the queue used by the trigger in RabbitMQ. Refer to the RabbitMQ documentation.

This section describes the configuration settings available for this binding in version 2.x and later. Settings in the host.json file apply to all functions in a function app instance. For more information about function app configuration settings, see host.json reference for Azure Functions.

{
    "version": "2.0",
    "extensions": {
        "rabbitMQ": {
            "prefetchCount": 100,
            "queueName": "queue",
            "connectionString": "amqp://user:password@url:port",
            "port": 10
        }
    }
}

Note

The connectionString takes precedence over "hostName", "userName", and "password". If these are all set, the connectionString will override the other two.

If you're testing locally without a connection string, you should set the "hostName" setting and "userName" and "password" if applicable in the "rabbitMQ" section of host.json:

{
    "version": "2.0",
    "extensions": {
        "rabbitMQ": {
            ...
            "hostName": "localhost",
            "username": "userNameSetting",
            "password": "passwordSetting"
        }
    }
}

In order for the RabbitMQ trigger to scale out to multiple instances, the Runtime Scale Monitoring setting must be enabled.

In the portal, this setting can be found under Configuration > Function runtime settings for your function app.

In the CLI, you can enable Runtime Scale Monitoring by using the following command:

az resource update -g <resource_group> -n <function_app_name>/config/web --set properties.functionsRuntimeScaleMonitoringEnabled=1 --resource-type Microsoft.Web/sites

To monitor your queues and exchanges for a certain RabbitMQ endpoint:

• Enable the RabbitMQ management plugin
• Browse to http://{node-hostname}:15672 and log in with your user name and password.

• Send RabbitMQ messages from Azure Functions (Output binding)

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