title	description	author	ms.topic	ms.date	ms.author	ms.devlang	ms.custom	zone_pivot_groups
RabbitMQ trigger for Azure Functions	Learn how to run an Azure Function when a RabbitMQ message is created.	cachai2	reference	01/21/2022	cachai	csharp	devx-track-extended-java, devx-track-js, devx-track-python	programming-languages-set-functions-lang-workers

RabbitMQ trigger for Azure Functions overview

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

[!INCLUDE functions-rabbitmq-plans-support-note]

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

Example

::: zone pivot="programming-language-csharp"

[!INCLUDE functions-bindings-csharp-intro-with-csx]

[!INCLUDE functions-in-process-model-retirement-note]

Isolated worker model

:::code language="csharp" source="~/azure-functions-dotnet-worker/samples/Extensions/RabbitMQ/RabbitMQFunction.cs" range="12-23" :::

In-process model

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.

::: zone-end ::: zone pivot="programming-language-java"

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);
}

::: zone-end
::: zone pivot="programming-language-javascript"

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);
};

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::: zone pivot="programming-language-python"

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)

::: zone-end
::: zone pivot="programming-language-powershell" ::: zone-end
::: zone pivot="programming-language-csharp"

Attributes

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:

Parameter	Description
QueueName	Name of the queue from which to receive messages.
HostName	Hostname of the queue, such as 10.26.45.210. Ignored when using `ConnectStringSetting`.
UserNameSetting	Name of the app setting that contains the username to access the queue, such as `UserNameSetting: "%< UserNameFromSettings >%"`. Ignored when using `ConnectStringSetting`.
PasswordSetting	Name of the app setting that contains the password to access the queue, such as `PasswordSetting: "%< PasswordFromSettings >%"`. Ignored when using `ConnectStringSetting`.
ConnectionStringSetting	The name of the app setting that contains the RabbitMQ message queue connection string. The trigger won't work when you specify the connection string directly instead through an app setting. For example, when you have set `ConnectionStringSetting: "rabbitMQConnection"`, then in both the local.settings.json and in your function app you need a setting like `"RabbitMQConnection" : "< ActualConnectionstring >"`.
Port	Gets or sets the port used. Defaults to 0, which points to the RabbitMQ client's default port setting of `5672`.

Isolated worker model

In C# class libraries, use the RabbitMQTrigger attribute.

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

:::code language="csharp" source="~/azure-functions-dotnet-worker/samples/Extensions/RabbitMQ/RabbitMQFunction.cs" range="12-16":::

In-process model

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)
{
    ...
}

::: zone-end
::: zone pivot="programming-language-java"

Annotations

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

The annotation supports the following configuration options:

Parameter	Description
queueName	Name of the queue from which to receive messages.
hostName	Hostname of the queue, such as 10.26.45.210. Ignored when using `ConnectStringSetting`.
userNameSetting	Name of the app setting that contains the username to access the queue, such as `UserNameSetting: "%< UserNameFromSettings >%"`. Ignored when using `ConnectStringSetting`.
passwordSetting	Name of the app setting that contains the password to access the queue, such as `PasswordSetting: "%< PasswordFromSettings >%"`. Ignored when using `ConnectStringSetting`.
connectionStringSetting	The name of the app setting that contains the RabbitMQ message queue connection string. The trigger won't work when you specify the connection string directly instead through an app setting. For example, when you have set `ConnectionStringSetting: "rabbitMQConnection"`, then in both the local.settings.json and in your function app you need a setting like `"RabbitMQConnection" : "< ActualConnectionstring >"`.
port	Gets or sets the port used. Defaults to 0, which points to the RabbitMQ client's default port setting of `5672`.

::: zone-end
::: zone pivot="programming-language-javascript,programming-language-python,programming-language-powershell"

Configuration

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

function.json property	Description
type	Must be set to `RabbitMQTrigger`.
direction	Must be set to `in`.
name	The name of the variable that represents the queue in function code.
queueName	Name of the queue from which to receive messages.
hostName	Hostname of the queue, such as 10.26.45.210. Ignored when using `connectStringSetting`.
userNameSetting	Name of the app setting that contains the username to access the queue, such as `UserNameSetting: "%< UserNameFromSettings >%"`. Ignored when using `connectStringSetting`.
passwordSetting	Name of the app setting that contains the password to access the queue, such as `PasswordSetting: "%< PasswordFromSettings >%"`. Ignored when using `connectStringSetting`.
connectionStringSetting	The name of the app setting that contains the RabbitMQ message queue connection string. The trigger won't work when you specify the connection string directly instead through an app setting. For example, when you have set `connectionStringSetting: "rabbitMQConnection"`, then in both the local.settings.json and in your function app you need a setting like `"rabbitMQConnection" : "< ActualConnectionstring >"`.
port	Gets or sets the port used. Defaults to 0, which points to the RabbitMQ client's default port setting of `5672`.

[!INCLUDE app settings to local.settings.json]

::: zone-end

See the Example section for complete examples.

Usage

[!INCLUDE functions-rabbitmq-managed-identity-note]

::: zone pivot="programming-language-csharp"
The parameter type supported by the RabbitMQ trigger depends on the C# modality used.

Isolated worker model

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

In-process model

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.

::: zone-end
::: zone pivot="programming-language-java"

Refer to Java annotations.

::: zone-end
::: zone pivot="programming-language-javascript"

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.

::: zone-end
::: zone pivot="programming-language-powershell" ::: zone-end
::: zone pivot="programming-language-python"

Refer to the Python example.

::: zone-end

Dead letter queues

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.

host.json settings

[!INCLUDE functions-host-json-section-intro]

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

Property	Default	Description
prefetchCount	30	Gets or sets the number of messages that the message receiver can simultaneously request and is cached.
queueName	n/a	Name of the queue to receive messages from.
connectionString	n/a	The RabbitMQ message queue connection string. The connection string is directly specified here and not through an app setting.
port	0	(ignored if using connectionString) Gets or sets the Port used. Defaults to 0, which points to rabbitmq client's default port setting: 5672.

Local testing

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"
        }
    }
}

Property	Default	Description
hostName	n/a	(ignored if using connectionString) Hostname of the queue (Ex: 10.26.45.210)
userName	n/a	(ignored if using connectionString) Name to access the queue
password	n/a	(ignored if using connectionString) Password to access the queue

Enable Runtime Scaling

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.

:::image type="content" source="media/functions-networking-options/virtual-network-trigger-toggle.png" alt-text="VNETToggle":::

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

Monitoring RabbitMQ endpoint

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.

Next steps

Send RabbitMQ messages from Azure Functions (Output binding)

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functions-bindings-rabbitmq-trigger.md

functions-bindings-rabbitmq-trigger.md

RabbitMQ trigger for Azure Functions overview

Example

Isolated worker model

In-process model

Attributes

Isolated worker model

In-process model

Annotations

Configuration

Usage

Isolated worker model

In-process model

Dead letter queues

host.json settings

Local testing

Enable Runtime Scaling

Monitoring RabbitMQ endpoint

Next steps

Files

functions-bindings-rabbitmq-trigger.md

Latest commit

History

functions-bindings-rabbitmq-trigger.md

File metadata and controls

RabbitMQ trigger for Azure Functions overview

Example

Isolated worker model

In-process model

Attributes

Isolated worker model

In-process model

Annotations

Configuration

Usage

Isolated worker model

In-process model

Dead letter queues

host.json settings

Local testing

Enable Runtime Scaling

Monitoring RabbitMQ endpoint

Next steps