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title description author ms.topic ms.date ms.author ms.devlang ms.custom zone_pivot_groups
RabbitMQ output bindings for Azure Functions
Learn to send RabbitMQ messages from Azure Functions.
cachai2
reference
01/21/2022
cachai
csharp
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]

[!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 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);
        }
    }
}

::: 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.

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 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)
{
    ...
}

::: 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.

Isolated worker model

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

In-process model

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.

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