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RabbitMQ output bindings for Azure Functions	Learn to send RabbitMQ messages from Azure Functions.	cachai2		reference	01/21/2022	cachai	csharp, java, javascript, python	devx-track-extended-java, devx-track-js, devx-track-python	programming-languages-set-functions-lang-workers

RabbitMQ output binding for Azure Functions overview

Note

The RabbitMQ bindings are only fully supported on Premium and Dedicated plans. Consumption is not supported.

Use the RabbitMQ output binding to send messages to a RabbitMQ queue.

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

Example

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

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

In-process

The following example shows a C# function that sends a RabbitMQ message when triggered by a TimerTrigger every 5 minutes using the method return value as the output:

[FunctionName("RabbitMQOutput")]
[return: RabbitMQ(QueueName = "outputQueue", ConnectionStringSetting = "rabbitMQConnectionAppSetting")]
public static string Run([TimerTrigger("0 */5 * * * *")] TimerInfo myTimer, ILogger log)
{
    log.LogInformation($"C# Timer trigger function executed at: {DateTime.Now}");
    return $"{DateTime.Now}";
}

The following example shows how to use the IAsyncCollector interface to send messages.

[FunctionName("RabbitMQOutput")]
public static async Task Run(
[RabbitMQTrigger("sourceQueue", ConnectionStringSetting = "rabbitMQConnectionAppSetting")] string rabbitMQEvent,
[RabbitMQ(QueueName = "destinationQueue", ConnectionStringSetting = "rabbitMQConnectionAppSetting")]IAsyncCollector<string> outputEvents,
ILogger log)
{
     // send the message
    await outputEvents.AddAsync(JsonConvert.SerializeObject(rabbitMQEvent));
}

The following example shows how to send the messages as POCOs.

namespace Company.Function
{
    public class TestClass
    {
        public string x { get; set; }
    }
    public static class RabbitMQOutput{
        [FunctionName("RabbitMQOutput")]
        public static async Task Run(
        [RabbitMQTrigger("sourceQueue", ConnectionStringSetting = "rabbitMQConnectionAppSetting")] TestClass rabbitMQEvent,
        [RabbitMQ(QueueName = "destinationQueue", ConnectionStringSetting = "rabbitMQConnectionAppSetting")]IAsyncCollector<TestClass> outputPocObj,
        ILogger log)
        {
            // send the message
            await outputPocObj.AddAsync(rabbitMQEvent);
        }
    }
}

Isolated process

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

C# Script

The following example shows a RabbitMQ output binding in a function.json file and a C# script function that uses the binding. The function reads in the message from an HTTP trigger and outputs it to the RabbitMQ queue.

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

{
    "bindings": [
        {
            "type": "httpTrigger",
            "direction": "in",
            "authLevel": "function",
            "name": "input",
            "methods": [
                "get",
                "post"
            ]
        },
        {
            "type": "rabbitMQ",
            "name": "outputMessage",
            "queueName": "outputQueue",
            "connectionStringSetting": "rabbitMQConnectionAppSetting",
            "direction": "out"
        }
    ]
}

Here's the C# script code:

using System;
using Microsoft.Extensions.Logging;

public static void Run(string input, out string outputMessage, ILogger log)
{
    log.LogInformation(input);
    outputMessage = input;
}

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

The following Java function uses the @RabbitMQOutput annotation from the Java RabbitMQ types to describe the configuration for a RabbitMQ queue output binding. The function sends a message to the RabbitMQ queue when triggered by a TimerTrigger every 5 minutes.

@FunctionName("RabbitMQOutputExample")
public void run(
@TimerTrigger(name = "keepAliveTrigger", schedule = "0 */5 * * * *") String timerInfo,
@RabbitMQOutput(connectionStringSetting = "rabbitMQConnectionAppSetting", queueName = "hello") OutputBinding<String> output,
final ExecutionContext context) {
    output.setValue("Some string");
}

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

The following example shows a RabbitMQ output binding in a function.json file and a JavaScript function that uses the binding. The function reads in the message from an HTTP trigger and outputs it to the RabbitMQ queue.

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

{
    "bindings": [
        {
            "type": "httpTrigger",
            "direction": "in",
            "authLevel": "function",
            "name": "input",
            "methods": [
                "get",
                "post"
            ]
        },
        {
            "type": "rabbitMQ",
            "name": "outputMessage",
            "queueName": "outputQueue",
            "connectionStringSetting": "rabbitMQConnectionAppSetting",
            "direction": "out"
        }
    ]
}

Here's JavaScript code:

module.exports = async function (context, input) {
    context.bindings.outputMessage = input.body;
};

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

The following example shows a RabbitMQ output binding in a function.json file and a Python function that uses the binding. The function reads in the message from an HTTP trigger and outputs it to the RabbitMQ queue.

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

{
    "scriptFile": "__init__.py",
    "bindings": [
        {
            "authLevel": "function",
            "type": "httpTrigger",
            "direction": "in",
            "name": "req",
            "methods": [
                "get",
                "post"
            ]
        },
        {
            "type": "http",
            "direction": "out",
            "name": "$return"
        },
        {
            "type": "rabbitMQ",
            "name": "outputMessage",
            "queueName": "outputQueue",
            "connectionStringSetting": "rabbitMQConnectionAppSetting",
            "direction": "out"
        }
    ]
}

In _init_.py:

import azure.functions as func

def main(req: func.HttpRequest, outputMessage: func.Out[str]) -> func.HttpResponse:
    input_msg = req.params.get('message')
    outputMessage.set(input_msg)
    return 'OK'

::: 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`.

In-process

In C# class libraries, use the RabbitMQAttribute.

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

[FunctionName("RabbitMQOutput")]
public static async Task Run(
[RabbitMQTrigger("SourceQueue", ConnectionStringSetting = "TriggerConnectionString")] string rabbitMQEvent,
[RabbitMQ("DestinationQueue", ConnectionStringSetting = "OutputConnectionString")]IAsyncCollector<string> outputEvents,
ILogger log)
{
    ...
}

Isolated process

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":::

C# script

C# script uses a function.json file for configuration instead of attributes.

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

function.json property	Description
type	Must be set to `RabbitMQ`.
direction	Must be set to `out`.
name	The name of the variable that represents the queue in function code.
queueName	See the QueueName attribute above.
hostName	See the HostName attribute above.
userNameSetting	See the UserNameSetting attribute above.
passwordSetting	See the PasswordSetting attribute above.
connectionStringSetting	See the ConnectionStringSetting attribute above.
port	See the Port attribute above.

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

Annotations

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

The annotation supports the following configuration settings:

Setting	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`.

See the output binding example for more detail.

::: zone-end
::: zone pivot="programming-language-javascript,programming-language-csharp,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 `RabbitMQ`.
direction	Must be set to `out`.
name	The name of the variable that represents the queue in function code.
queueName	Name of the queue to send messages to.
hostName	Hostname of the queue, such as 10.26.45.210. Ignored when using `connectStringSetting`.
userName	Name of the app setting that contains the username to access the queue, such as UserNameSetting: "< UserNameFromSettings >". Ignored when using `connectStringSetting`.
password	Name of the app setting that contains the password to access the queue, such as UserNameSetting: "< UserNameFromSettings >". 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 of through an app setting in `local.settings.json`. 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

::: zone pivot="programming-language-csharp"
The parameter type supported by the RabbitMQ trigger depends on the Functions runtime version, the extension package version, and the C# modality used.

In-process

Use the following parameter types for the output binding:

byte[] - If the parameter value is null when the function exits, Functions doesn't create a message.
string - If the parameter value is null when the function exits, Functions doesn't create a message.
POCO - The message is formatted as a C# object.

When working with C# functions:

Async functions need a return value or IAsyncCollector instead of an out parameter.

Isolated process

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

C# script

Use the following parameter types for the output binding:

byte[] - If the parameter value is null when the function exits, Functions doesn't create a message.
string - If the parameter value is null when the function exits, Functions doesn't create a message.
POCO - If the parameter value isn't formatted as a C# object, an error will be received. For a complete example, see C# Script example.

When working with C# Script functions:

Async functions need a return value or IAsyncCollector instead of an out parameter.

For a complete example, see C# example.

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

Use the following parameter types for the output binding:

byte[] - If the parameter value is null when the function exits, Functions doesn't create a message.
string - If the parameter value is null when the function exits, Functions doesn't create a message.
POJO - If the parameter value isn't formatted as a Java object, an error will be received.

::: 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

Next steps

Run a function when a RabbitMQ message is created (Trigger)

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functions-bindings-rabbitmq-output.md

functions-bindings-rabbitmq-output.md

RabbitMQ output binding for Azure Functions overview

Example

In-process

Isolated process

C# Script

Attributes

In-process

Isolated process

C# script

Annotations

Configuration

Usage

In-process

Isolated process

C# script

Next steps

Files

functions-bindings-rabbitmq-output.md

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functions-bindings-rabbitmq-output.md

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RabbitMQ output binding for Azure Functions overview

Example

Attributes

Annotations

Configuration

Usage

Next steps