Azure Service Bus trigger for Azure Functions
Use the Service Bus trigger to respond to messages from a Service Bus queue or topic. Starting with extension version 3.1.0, you can trigger on a session-enabled queue or topic.
For information on setup and configuration details, see the overview.
Service Bus scaling decisions for the Consumption and Premium plans are made based on target-based scaling. For more information, see Target-based scaling.
Important
This article uses tabs to support multiple versions of the Node.js programming model. The v4 model is currently in preview and is designed to have a more flexible and intuitive experience for JavaScript and TypeScript developers. Learn more about the differences between v3 and v4 in the upgrade guide.
Azure Functions supports two programming models for Python. The way that you define your bindings depends on your chosen programming model.
The Python v2 programming model lets you define bindings using decorators directly in your Python function code. For more information, see the Python developer guide.
This article supports both programming models.
Example
A C# function can be created using one of the following C# modes:
- In-process class library: compiled C# function that runs in the same process as the Functions runtime.
- Isolated worker process class library: compiled C# function that runs in a worker process that is isolated from the runtime. Isolated worker process is required to support C# functions running on non-LTS versions .NET and the .NET Framework.
- C# script: used primarily when creating C# functions in the Azure portal.
Important
Support will end for the in-process model on November 10, 2026. We highly recommend that you migrate your apps to the isolated worker model for full support.
This code defines and initializes the ILogger
:
// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the MIT License. See License.txt in the project root for license information.
using System;
using System.Threading.Tasks;
using Azure.Messaging.ServiceBus;
using Microsoft.Azure.Functions.Worker;
using Microsoft.Extensions.Logging;
namespace SampleApp
{
/// <summary>
/// Samples demonstrating binding to the <see cref="ServiceBusReceivedMessage"/> type.
/// </summary>
public class ServiceBusReceivedMessageFunctions
{
//<docsnippet_servicebusmessage_createlogger>
private readonly ILogger<ServiceBusReceivedMessageFunctions> _logger;
public ServiceBusReceivedMessageFunctions(ILogger<ServiceBusReceivedMessageFunctions> logger)
{
_logger = logger;
}
//</docsnippet_servicebusmessage_createlogger>
/// <summary>
/// This function demonstrates binding to a single <see cref="ServiceBusReceivedMessage"/>.
/// </summary>
//<docsnippet_servicebus_readmessage>
[Function(nameof(ServiceBusReceivedMessageFunction))]
[ServiceBusOutput("outputQueue", Connection = "ServiceBusConnection")]
public string ServiceBusReceivedMessageFunction(
[ServiceBusTrigger("queue", Connection = "ServiceBusConnection")] ServiceBusReceivedMessage message)
{
_logger.LogInformation("Message ID: {id}", message.MessageId);
_logger.LogInformation("Message Body: {body}", message.Body);
_logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);
var outputMessage = $"Output message created at {DateTime.Now}";
return outputMessage;
}
//</docsnippet_servicebus_readmessage>
/// <summary>
/// This function demonstrates binding to an array of <see cref="ServiceBusReceivedMessage"/>.
/// Note that when doing so, you must also set the <see cref="ServiceBusTriggerAttribute.IsBatched"/> property
/// to <value>true</value>.
/// </summary>
//<docsnippet_servicebus_readbatch>
[Function(nameof(ServiceBusReceivedMessageBatchFunction))]
public void ServiceBusReceivedMessageBatchFunction(
[ServiceBusTrigger("queue", Connection = "ServiceBusConnection", IsBatched = true)] ServiceBusReceivedMessage[] messages)
{
foreach (ServiceBusReceivedMessage message in messages)
{
_logger.LogInformation("Message ID: {id}", message.MessageId);
_logger.LogInformation("Message Body: {body}", message.Body);
_logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);
}
}
//</docsnippet_servicebus_readbatch>
/// <summary>
/// This functions demonstrates that it is possible to bind to both the ServiceBusReceivedMessage and any of the supported binding contract
/// properties at the same time. If attempting this, the ServiceBusReceivedMessage must be the first parameter. There is not
/// much benefit to doing this as all of the binding contract properties are available as properties on the ServiceBusReceivedMessage.
/// </summary>
[Function(nameof(ServiceBusReceivedMessageWithStringProperties))]
public void ServiceBusReceivedMessageWithStringProperties(
[ServiceBusTrigger("queue", Connection = "ServiceBusConnection")]
ServiceBusReceivedMessage message, string messageId, int deliveryCount)
{
// The MessageId property and the messageId parameter are the same.
_logger.LogInformation("Message ID: {id}", message.MessageId);
_logger.LogInformation("Message ID: {id}", messageId);
// Similarly the DeliveryCount property and the deliveryCount parameter are the same.
_logger.LogInformation("Delivery Count: {count}", message.DeliveryCount);
_logger.LogInformation("Delivery Count: {count}", deliveryCount);
}
//<docsnippet_servicebus_message_actions>
[Function(nameof(ServiceBusMessageActionsFunction))]
public async Task ServiceBusMessageActionsFunction(
[ServiceBusTrigger("queue", Connection = "ServiceBusConnection", AutoCompleteMessages = false)]
ServiceBusReceivedMessage message,
ServiceBusMessageActions messageActions)
{
_logger.LogInformation("Message ID: {id}", message.MessageId);
_logger.LogInformation("Message Body: {body}", message.Body);
_logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);
// Complete the message
await messageActions.CompleteMessageAsync(message);
}
//</docsnippet_servicebus_message_actions>
}
}
This example shows a C# function that receives a single Service Bus queue message and writes it to the logs:
// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the MIT License. See License.txt in the project root for license information.
using System;
using System.Threading.Tasks;
using Azure.Messaging.ServiceBus;
using Microsoft.Azure.Functions.Worker;
using Microsoft.Extensions.Logging;
namespace SampleApp
{
/// <summary>
/// Samples demonstrating binding to the <see cref="ServiceBusReceivedMessage"/> type.
/// </summary>
public class ServiceBusReceivedMessageFunctions
{
//<docsnippet_servicebusmessage_createlogger>
private readonly ILogger<ServiceBusReceivedMessageFunctions> _logger;
public ServiceBusReceivedMessageFunctions(ILogger<ServiceBusReceivedMessageFunctions> logger)
{
_logger = logger;
}
//</docsnippet_servicebusmessage_createlogger>
/// <summary>
/// This function demonstrates binding to a single <see cref="ServiceBusReceivedMessage"/>.
/// </summary>
//<docsnippet_servicebus_readmessage>
[Function(nameof(ServiceBusReceivedMessageFunction))]
[ServiceBusOutput("outputQueue", Connection = "ServiceBusConnection")]
public string ServiceBusReceivedMessageFunction(
[ServiceBusTrigger("queue", Connection = "ServiceBusConnection")] ServiceBusReceivedMessage message)
{
_logger.LogInformation("Message ID: {id}", message.MessageId);
_logger.LogInformation("Message Body: {body}", message.Body);
_logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);
var outputMessage = $"Output message created at {DateTime.Now}";
return outputMessage;
}
//</docsnippet_servicebus_readmessage>
/// <summary>
/// This function demonstrates binding to an array of <see cref="ServiceBusReceivedMessage"/>.
/// Note that when doing so, you must also set the <see cref="ServiceBusTriggerAttribute.IsBatched"/> property
/// to <value>true</value>.
/// </summary>
//<docsnippet_servicebus_readbatch>
[Function(nameof(ServiceBusReceivedMessageBatchFunction))]
public void ServiceBusReceivedMessageBatchFunction(
[ServiceBusTrigger("queue", Connection = "ServiceBusConnection", IsBatched = true)] ServiceBusReceivedMessage[] messages)
{
foreach (ServiceBusReceivedMessage message in messages)
{
_logger.LogInformation("Message ID: {id}", message.MessageId);
_logger.LogInformation("Message Body: {body}", message.Body);
_logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);
}
}
//</docsnippet_servicebus_readbatch>
/// <summary>
/// This functions demonstrates that it is possible to bind to both the ServiceBusReceivedMessage and any of the supported binding contract
/// properties at the same time. If attempting this, the ServiceBusReceivedMessage must be the first parameter. There is not
/// much benefit to doing this as all of the binding contract properties are available as properties on the ServiceBusReceivedMessage.
/// </summary>
[Function(nameof(ServiceBusReceivedMessageWithStringProperties))]
public void ServiceBusReceivedMessageWithStringProperties(
[ServiceBusTrigger("queue", Connection = "ServiceBusConnection")]
ServiceBusReceivedMessage message, string messageId, int deliveryCount)
{
// The MessageId property and the messageId parameter are the same.
_logger.LogInformation("Message ID: {id}", message.MessageId);
_logger.LogInformation("Message ID: {id}", messageId);
// Similarly the DeliveryCount property and the deliveryCount parameter are the same.
_logger.LogInformation("Delivery Count: {count}", message.DeliveryCount);
_logger.LogInformation("Delivery Count: {count}", deliveryCount);
}
//<docsnippet_servicebus_message_actions>
[Function(nameof(ServiceBusMessageActionsFunction))]
public async Task ServiceBusMessageActionsFunction(
[ServiceBusTrigger("queue", Connection = "ServiceBusConnection", AutoCompleteMessages = false)]
ServiceBusReceivedMessage message,
ServiceBusMessageActions messageActions)
{
_logger.LogInformation("Message ID: {id}", message.MessageId);
_logger.LogInformation("Message Body: {body}", message.Body);
_logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);
// Complete the message
await messageActions.CompleteMessageAsync(message);
}
//</docsnippet_servicebus_message_actions>
}
}
This example shows a C# function that receives multiple Service Bus queue messages in a single batch and writes each to the logs:
// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the MIT License. See License.txt in the project root for license information.
using System;
using System.Threading.Tasks;
using Azure.Messaging.ServiceBus;
using Microsoft.Azure.Functions.Worker;
using Microsoft.Extensions.Logging;
namespace SampleApp
{
/// <summary>
/// Samples demonstrating binding to the <see cref="ServiceBusReceivedMessage"/> type.
/// </summary>
public class ServiceBusReceivedMessageFunctions
{
//<docsnippet_servicebusmessage_createlogger>
private readonly ILogger<ServiceBusReceivedMessageFunctions> _logger;
public ServiceBusReceivedMessageFunctions(ILogger<ServiceBusReceivedMessageFunctions> logger)
{
_logger = logger;
}
//</docsnippet_servicebusmessage_createlogger>
/// <summary>
/// This function demonstrates binding to a single <see cref="ServiceBusReceivedMessage"/>.
/// </summary>
//<docsnippet_servicebus_readmessage>
[Function(nameof(ServiceBusReceivedMessageFunction))]
[ServiceBusOutput("outputQueue", Connection = "ServiceBusConnection")]
public string ServiceBusReceivedMessageFunction(
[ServiceBusTrigger("queue", Connection = "ServiceBusConnection")] ServiceBusReceivedMessage message)
{
_logger.LogInformation("Message ID: {id}", message.MessageId);
_logger.LogInformation("Message Body: {body}", message.Body);
_logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);
var outputMessage = $"Output message created at {DateTime.Now}";
return outputMessage;
}
//</docsnippet_servicebus_readmessage>
/// <summary>
/// This function demonstrates binding to an array of <see cref="ServiceBusReceivedMessage"/>.
/// Note that when doing so, you must also set the <see cref="ServiceBusTriggerAttribute.IsBatched"/> property
/// to <value>true</value>.
/// </summary>
//<docsnippet_servicebus_readbatch>
[Function(nameof(ServiceBusReceivedMessageBatchFunction))]
public void ServiceBusReceivedMessageBatchFunction(
[ServiceBusTrigger("queue", Connection = "ServiceBusConnection", IsBatched = true)] ServiceBusReceivedMessage[] messages)
{
foreach (ServiceBusReceivedMessage message in messages)
{
_logger.LogInformation("Message ID: {id}", message.MessageId);
_logger.LogInformation("Message Body: {body}", message.Body);
_logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);
}
}
//</docsnippet_servicebus_readbatch>
/// <summary>
/// This functions demonstrates that it is possible to bind to both the ServiceBusReceivedMessage and any of the supported binding contract
/// properties at the same time. If attempting this, the ServiceBusReceivedMessage must be the first parameter. There is not
/// much benefit to doing this as all of the binding contract properties are available as properties on the ServiceBusReceivedMessage.
/// </summary>
[Function(nameof(ServiceBusReceivedMessageWithStringProperties))]
public void ServiceBusReceivedMessageWithStringProperties(
[ServiceBusTrigger("queue", Connection = "ServiceBusConnection")]
ServiceBusReceivedMessage message, string messageId, int deliveryCount)
{
// The MessageId property and the messageId parameter are the same.
_logger.LogInformation("Message ID: {id}", message.MessageId);
_logger.LogInformation("Message ID: {id}", messageId);
// Similarly the DeliveryCount property and the deliveryCount parameter are the same.
_logger.LogInformation("Delivery Count: {count}", message.DeliveryCount);
_logger.LogInformation("Delivery Count: {count}", deliveryCount);
}
//<docsnippet_servicebus_message_actions>
[Function(nameof(ServiceBusMessageActionsFunction))]
public async Task ServiceBusMessageActionsFunction(
[ServiceBusTrigger("queue", Connection = "ServiceBusConnection", AutoCompleteMessages = false)]
ServiceBusReceivedMessage message,
ServiceBusMessageActions messageActions)
{
_logger.LogInformation("Message ID: {id}", message.MessageId);
_logger.LogInformation("Message Body: {body}", message.Body);
_logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);
// Complete the message
await messageActions.CompleteMessageAsync(message);
}
//</docsnippet_servicebus_message_actions>
}
}
This example shows a C# function that receives multiple Service Bus queue messages, writes it to the logs, and then settles the message as completed:
// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the MIT License. See License.txt in the project root for license information.
using System;
using System.Threading.Tasks;
using Azure.Messaging.ServiceBus;
using Microsoft.Azure.Functions.Worker;
using Microsoft.Extensions.Logging;
namespace SampleApp
{
/// <summary>
/// Samples demonstrating binding to the <see cref="ServiceBusReceivedMessage"/> type.
/// </summary>
public class ServiceBusReceivedMessageFunctions
{
//<docsnippet_servicebusmessage_createlogger>
private readonly ILogger<ServiceBusReceivedMessageFunctions> _logger;
public ServiceBusReceivedMessageFunctions(ILogger<ServiceBusReceivedMessageFunctions> logger)
{
_logger = logger;
}
//</docsnippet_servicebusmessage_createlogger>
/// <summary>
/// This function demonstrates binding to a single <see cref="ServiceBusReceivedMessage"/>.
/// </summary>
//<docsnippet_servicebus_readmessage>
[Function(nameof(ServiceBusReceivedMessageFunction))]
[ServiceBusOutput("outputQueue", Connection = "ServiceBusConnection")]
public string ServiceBusReceivedMessageFunction(
[ServiceBusTrigger("queue", Connection = "ServiceBusConnection")] ServiceBusReceivedMessage message)
{
_logger.LogInformation("Message ID: {id}", message.MessageId);
_logger.LogInformation("Message Body: {body}", message.Body);
_logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);
var outputMessage = $"Output message created at {DateTime.Now}";
return outputMessage;
}
//</docsnippet_servicebus_readmessage>
/// <summary>
/// This function demonstrates binding to an array of <see cref="ServiceBusReceivedMessage"/>.
/// Note that when doing so, you must also set the <see cref="ServiceBusTriggerAttribute.IsBatched"/> property
/// to <value>true</value>.
/// </summary>
//<docsnippet_servicebus_readbatch>
[Function(nameof(ServiceBusReceivedMessageBatchFunction))]
public void ServiceBusReceivedMessageBatchFunction(
[ServiceBusTrigger("queue", Connection = "ServiceBusConnection", IsBatched = true)] ServiceBusReceivedMessage[] messages)
{
foreach (ServiceBusReceivedMessage message in messages)
{
_logger.LogInformation("Message ID: {id}", message.MessageId);
_logger.LogInformation("Message Body: {body}", message.Body);
_logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);
}
}
//</docsnippet_servicebus_readbatch>
/// <summary>
/// This functions demonstrates that it is possible to bind to both the ServiceBusReceivedMessage and any of the supported binding contract
/// properties at the same time. If attempting this, the ServiceBusReceivedMessage must be the first parameter. There is not
/// much benefit to doing this as all of the binding contract properties are available as properties on the ServiceBusReceivedMessage.
/// </summary>
[Function(nameof(ServiceBusReceivedMessageWithStringProperties))]
public void ServiceBusReceivedMessageWithStringProperties(
[ServiceBusTrigger("queue", Connection = "ServiceBusConnection")]
ServiceBusReceivedMessage message, string messageId, int deliveryCount)
{
// The MessageId property and the messageId parameter are the same.
_logger.LogInformation("Message ID: {id}", message.MessageId);
_logger.LogInformation("Message ID: {id}", messageId);
// Similarly the DeliveryCount property and the deliveryCount parameter are the same.
_logger.LogInformation("Delivery Count: {count}", message.DeliveryCount);
_logger.LogInformation("Delivery Count: {count}", deliveryCount);
}
//<docsnippet_servicebus_message_actions>
[Function(nameof(ServiceBusMessageActionsFunction))]
public async Task ServiceBusMessageActionsFunction(
[ServiceBusTrigger("queue", Connection = "ServiceBusConnection", AutoCompleteMessages = false)]
ServiceBusReceivedMessage message,
ServiceBusMessageActions messageActions)
{
_logger.LogInformation("Message ID: {id}", message.MessageId);
_logger.LogInformation("Message Body: {body}", message.Body);
_logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);
// Complete the message
await messageActions.CompleteMessageAsync(message);
}
//</docsnippet_servicebus_message_actions>
}
}
The following Java function uses the @ServiceBusQueueTrigger
annotation from the Java functions runtime library to describe the configuration for a Service Bus queue trigger. The function grabs the message placed on the queue and adds it to the logs.
@FunctionName("sbprocessor")
public void serviceBusProcess(
@ServiceBusQueueTrigger(name = "msg",
queueName = "myqueuename",
connection = "myconnvarname") String message,
final ExecutionContext context
) {
context.getLogger().info(message);
}
Java functions can also be triggered when a message is added to a Service Bus topic. The following example uses the @ServiceBusTopicTrigger
annotation to describe the trigger configuration.
@FunctionName("sbtopicprocessor")
public void run(
@ServiceBusTopicTrigger(
name = "message",
topicName = "mytopicname",
subscriptionName = "mysubscription",
connection = "ServiceBusConnection"
) String message,
final ExecutionContext context
) {
context.getLogger().info(message);
}
The following example shows a Service Bus trigger TypeScript function. The function reads message metadata and logs a Service Bus queue message.
import { app, InvocationContext } from '@azure/functions';
export async function serviceBusQueueTrigger1(message: unknown, context: InvocationContext): Promise<void> {
context.log('Service bus queue function processed message:', message);
context.log('EnqueuedTimeUtc =', context.triggerMetadata.enqueuedTimeUtc);
context.log('DeliveryCount =', context.triggerMetadata.deliveryCount);
context.log('MessageId =', context.triggerMetadata.messageId);
}
app.serviceBusQueue('serviceBusQueueTrigger1', {
connection: 'MyServiceBusConnection',
queueName: 'testqueue',
handler: serviceBusQueueTrigger1,
});
The following example shows a Service Bus trigger JavaScript function. The function reads message metadata and logs a Service Bus queue message.
const { app } = require('@azure/functions');
app.serviceBusQueue('serviceBusQueueTrigger1', {
connection: 'MyServiceBusConnection',
queueName: 'testqueue',
handler: (message, context) => {
context.log('Service bus queue function processed message:', message);
context.log('EnqueuedTimeUtc =', context.triggerMetadata.enqueuedTimeUtc);
context.log('DeliveryCount =', context.triggerMetadata.deliveryCount);
context.log('MessageId =', context.triggerMetadata.messageId);
},
});
The following example shows a Service Bus trigger binding in a function.json file and a PowerShell function that uses the binding.
Here's the binding data in the function.json file:
{
"bindings": [
{
"name": "mySbMsg",
"type": "serviceBusTrigger",
"direction": "in",
"topicName": "mytopic",
"subscriptionName": "mysubscription",
"connection": "AzureServiceBusConnectionString"
}
]
}
Here's the function that runs when a Service Bus message is sent.
param([string] $mySbMsg, $TriggerMetadata)
Write-Host "PowerShell ServiceBus queue trigger function processed message: $mySbMsg"
The following example demonstrates how to read a Service Bus queue message via a trigger. The example depends on whether you use the v1 or v2 Python programming model.
import logging
import azure.functions as func
app = func.FunctionApp()
@app.function_name(name="ServiceBusQueueTrigger1")
@app.service_bus_queue_trigger(arg_name="msg",
queue_name="<QUEUE_NAME>",
connection="<CONNECTION_SETTING>")
def test_function(msg: func.ServiceBusMessage):
logging.info('Python ServiceBus queue trigger processed message: %s',
msg.get_body().decode('utf-8'))
The following example demonstrates how to read a Service Bus queue topic via a trigger.
import logging
import azure.functions as func
app = func.FunctionApp()
@app.function_name(name="ServiceBusTopicTrigger1")
@app.service_bus_topic_trigger(arg_name="message",
topic_name="TOPIC_NAME",
connection="CONNECTION_SETTING",
subscription_name="SUBSCRIPTION_NAME")
def test_function(message: func.ServiceBusMessage):
message_body = message.get_body().decode("utf-8")
logging.info("Python ServiceBus topic trigger processed message.")
logging.info("Message Body: " + message_body)
Attributes
Both in-process and isolated worker process C# libraries use the ServiceBusTriggerAttribute attribute to define the function trigger. C# script instead uses a function.json configuration file as described in the C# scripting guide.
The following table explains the properties you can set using this trigger attribute:
Property | Description |
---|---|
QueueName | Name of the queue to monitor. Set only if monitoring a queue, not for a topic. |
TopicName | Name of the topic to monitor. Set only if monitoring a topic, not for a queue. |
SubscriptionName | Name of the subscription to monitor. Set only if monitoring a topic, not for a queue. |
Connection | The name of an app setting or setting collection that specifies how to connect to Service Bus. See Connections. |
IsBatched | Messages are delivered in batches. Requires an array or collection type. |
IsSessionsEnabled | true if connecting to a session-aware queue or subscription. false otherwise, which is the default value. |
AutoCompleteMessages | true if the trigger should automatically complete the message after a successful invocation. false if it should not, such as when you are handling message settlement in code. If not explicitly set, the behavior will be based on the autoCompleteMessages configuration in host.json . |
When you're developing locally, add your application settings in the local.settings.json file in the Values
collection.
Decorators
Applies only to the Python v2 programming model.
For Python v2 functions defined using a decorator, the following properties on the service_bus_queue_trigger
:
Property | Description |
---|---|
arg_name |
The name of the variable that represents the queue or topic message in function code. |
queue_name |
Name of the queue to monitor. Set only if monitoring a queue, not for a topic. |
connection |
The name of an app setting or setting collection that specifies how to connect to Service Bus. See Connections. |
For Python functions defined by using function.json, see the Configuration section.
Annotations
The ServiceBusQueueTrigger
annotation allows you to create a function that runs when a Service Bus queue message is created. Configuration options available include the following properties:
Property | Description |
---|---|
name | The name of the variable that represents the queue or topic message in function code. |
queueName | Name of the queue to monitor. Set only if monitoring a queue, not for a topic. |
topicName | Name of the topic to monitor. Set only if monitoring a topic, not for a queue. |
subscriptionName | Name of the subscription to monitor. Set only if monitoring a topic, not for a queue. |
connection | The name of an app setting or setting collection that specifies how to connect to Service Bus. See Connections. |
The ServiceBusTopicTrigger
annotation allows you to designate a topic and subscription to target what data triggers the function.
When you're developing locally, add your application settings in the local.settings.json file in the Values
collection.
See the trigger example for more detail.
Configuration
Applies only to the Python v1 programming model.
The following table explains the properties that you can set on the options
object passed to the app.serviceBusQueue()
or app.serviceBusTopic()
methods.
Property | Description |
---|---|
queueName | Name of the queue to monitor. Set only if monitoring a queue, not for a topic. |
topicName | Name of the topic to monitor. Set only if monitoring a topic, not for a queue. |
subscriptionName | Name of the subscription to monitor. Set only if monitoring a topic, not for a queue. |
connection | The name of an app setting or setting collection that specifies how to connect to Service Bus. See Connections. |
accessRights | Access rights for the connection string. Available values are manage and listen . The default is manage , which indicates that the connection has the Manage permission. If you use a connection string that does not have the Manage permission, set accessRights to "listen". Otherwise, the Functions runtime might fail trying to do operations that require manage rights. In Azure Functions version 2.x and higher, this property is not available because the latest version of the Service Bus SDK doesn't support manage operations. |
isSessionsEnabled | true if connecting to a session-aware queue or subscription. false otherwise, which is the default value. |
autoComplete | Must be true for non-C# functions, which means that the trigger should either automatically call complete after processing, or the function code manually calls complete.When set to true , the trigger completes the message automatically if the function execution completes successfully, and abandons the message otherwise.Exceptions in the function results in the runtime calls abandonAsync in the background. If no exception occurs, then completeAsync is called in the background. This property is available only in Azure Functions 2.x and higher. |
When you're developing locally, add your application settings in the local.settings.json file in the Values
collection.
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 serviceBusTrigger . This property is set automatically when you create the trigger in the Azure portal. |
direction | Must be set to "in". This property is set automatically when you create the trigger in the Azure portal. |
name | The name of the variable that represents the queue or topic message in function code. |
queueName | Name of the queue to monitor. Set only if monitoring a queue, not for a topic. |
topicName | Name of the topic to monitor. Set only if monitoring a topic, not for a queue. |
subscriptionName | Name of the subscription to monitor. Set only if monitoring a topic, not for a queue. |
connection | The name of an app setting or setting collection that specifies how to connect to Service Bus. See Connections. |
accessRights | Access rights for the connection string. Available values are manage and listen . The default is manage , which indicates that the connection has the Manage permission. If you use a connection string that does not have the Manage permission, set accessRights to "listen". Otherwise, the Functions runtime might fail trying to do operations that require manage rights. In Azure Functions version 2.x and higher, this property is not available because the latest version of the Service Bus SDK doesn't support manage operations. |
isSessionsEnabled | true if connecting to a session-aware queue or subscription. false otherwise, which is the default value. |
autoComplete | Must be true for non-C# functions, which means that the trigger should either automatically call complete after processing, or the function code manually calls complete.When set to true , the trigger completes the message automatically if the function execution completes successfully, and abandons the message otherwise.Exceptions in the function results in the runtime calls abandonAsync in the background. If no exception occurs, then completeAsync is called in the background. This property is available only in Azure Functions 2.x and higher. |
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.
Usage
The following parameter types are supported by all C# modalities and extension versions:
Type | Description |
---|---|
System.String | Use when the message is simple text. |
byte[] | Use for binary data messages. |
Object | When a message contains JSON, Functions tries to deserialize the JSON data into known plain-old CLR object type. |
Messaging-specific parameter types contain additional message metadata. The specific types supported by the Service Bus trigger depend on the Functions runtime version, the extension package version, and the C# modality used.
When you want the function to process a single message, the Service Bus trigger can bind to the following types:
Type | Description |
---|---|
string |
The message as a string. Use when the message is simple text. |
byte[] |
The bytes of the message. |
JSON serializable types | When a event contains JSON data, Functions tries to deserialize the JSON data into a plain-old CLR object (POCO) type. |
ServiceBusReceivedMessage | (Preview1) The message object. |
When you want the function to process a batch of messages, the Service Bus trigger can bind to the following types:
Type | Description |
---|---|
T[] where T is one of the single message types |
An array of events from the batch. Each entry represents one event. |
The isolated process model does not yet support message settlement scenarios for Service Bus triggers.
1 To use these types, you need to reference Microsoft.Azure.Functions.Worker.Extensions.ServiceBus 5.10.0-preview2 or later and the common dependencies for SDK type bindings.
When the Connection
property isn't defined, Functions looks for an app setting named AzureWebJobsServiceBus
, which is the default name for the Service Bus connection string. You can also set the Connection
property to specify the name of an application setting that contains the Service Bus connection string to use.
The incoming Service Bus message is available via a ServiceBusQueueMessage
or ServiceBusTopicMessage
parameter.
The Service Bus instance is available via the parameter configured in the function.json file's name property.
The queue message is available to the function via a parameter typed as func.ServiceBusMessage
. The Service Bus message is passed into the function as either a string or JSON object.
For a complete example, see the examples section.
Connections
The connection
property is a reference to environment configuration which specifies how the app should connect to Service Bus. It may specify:
- The name of an application setting containing a connection string
- The name of a shared prefix for multiple application settings, together defining an identity-based connection.
If the configured value is both an exact match for a single setting and a prefix match for other settings, the exact match is used.
Connection string
To obtain a connection string, follow the steps shown at Get the management credentials. The connection string must be for a Service Bus namespace, not limited to a specific queue or topic.
This connection string should be stored in an application setting with a name matching the value specified by the connection
property of the binding configuration.
If the app setting name begins with "AzureWebJobs", you can specify only the remainder of the name. For example, if you set connection
to "MyServiceBus", the Functions runtime looks for an app setting that is named "AzureWebJobsMyServiceBus". If you leave connection
empty, the Functions runtime uses the default Service Bus connection string in the app setting that is named "AzureWebJobsServiceBus".
Identity-based connections
If you are using version 5.x or higher of the extension, instead of using a connection string with a secret, you can have the app use an Azure Active Directory identity. To do this, you would define settings under a common prefix which maps to the connection
property in the trigger and binding configuration.
In this mode, the extension requires the following properties:
Property | Environment variable template | Description | Example value |
---|---|---|---|
Fully Qualified Namespace | <CONNECTION_NAME_PREFIX>__fullyQualifiedNamespace |
The fully qualified Service Bus namespace. | <service_bus_namespace>.servicebus.chinacloudapi.cn |
Additional properties may be set to customize the connection. See Common properties for identity-based connections.
Note
When using Azure App Configuration or Key Vault to provide settings for Managed Identity connections, setting names should use a valid key separator such as :
or /
in place of the __
to ensure names are resolved correctly.
For example, <CONNECTION_NAME_PREFIX>:fullyQualifiedNamespace
.
When hosted in the Azure Functions service, identity-based connections use a managed identity. The system-assigned identity is used by default, although a user-assigned identity can be specified with the credential
and clientID
properties. Note that configuring a user-assigned identity with a resource ID is not supported. When run in other contexts, such as local development, your developer identity is used instead, although this can be customized. See Local development with identity-based connections.
Grant permission to the identity
Whatever identity is being used must have permissions to perform the intended actions. For most Azure services, this means you need to assign a role in Azure RBAC, using either built-in or custom roles which provide those permissions.
Important
Some permissions might be exposed by the target service that are not necessary for all contexts. Where possible, adhere to the principle of least privilege, granting the identity only required privileges. For example, if the app only needs to be able to read from a data source, use a role that only has permission to read. It would be inappropriate to assign a role that also allows writing to that service, as this would be excessive permission for a read operation. Similarly, you would want to ensure the role assignment is scoped only over the resources that need to be read.
You'll need to create a role assignment that provides access to your topics and queues at runtime. Management roles like Owner aren't sufficient. The following table shows built-in roles that are recommended when using the Service Bus extension in normal operation. Your application may require additional permissions based on the code you write.
Binding type | Example built-in roles |
---|---|
Trigger1 | Azure Service Bus Data Receiver, Azure Service Bus Data Owner |
Output binding | Azure Service Bus Data Sender |
1 For triggering from Service Bus topics, the role assignment needs to have effective scope over the Service Bus subscription resource. If only the topic is included, an error will occur. Some clients, such as the Azure portal, don't expose the Service Bus subscription resource as a scope for role assignment. In such cases, the Azure CLI may be used instead. To learn more, see Azure built-in roles for Azure Service Bus.
Poison messages
Poison message handling can't be controlled or configured in Azure Functions. Service Bus handles poison messages itself.
PeekLock behavior
The Functions runtime receives a message in PeekLock mode.
By default, the runtime calls Complete
on the message if the function finishes successfully, or calls Abandon
if the function fails. You can disable automatic completion through with the autoCompleteMessages
property in host.json
.
By default, the runtime calls Complete
on the message if the function finishes successfully, or calls Abandon
if the function fails. You can disable automatic completion through with the autoCompleteMessages
property in host.json
or through a property on the trigger attribute. You should disable automatic completion if your function code handles message settlement.
If the function runs longer than the PeekLock
timeout, the lock is automatically renewed as long as the function is running. The maxAutoRenewDuration
is configurable in host.json, which maps to ServiceBusProcessor.MaxAutoLockRenewalDuration. The default value of this setting is 5 minutes.
Message metadata
Messaging-specific types let you easily retrieve metadata as properties of the object. These properties depend on the Functions runtime version, the extension package version, and the C# modality used.
These properties are members of the ServiceBusReceivedMessage class.
Property | Type | Description |
---|---|---|
ApplicationProperties |
ApplicationProperties |
Properties set by the sender. |
ContentType |
string |
A content type identifier utilized by the sender and receiver for application-specific logic. |
CorrelationId |
string |
The correlation ID. |
DeliveryCount |
Int32 |
The number of deliveries. |
EnqueuedTime |
DateTime |
The enqueued time in UTC. |
ScheduledEnqueueTimeUtc |
DateTime |
The scheduled enqueued time in UTC. |
ExpiresAt |
DateTime |
The expiration time in UTC. |
MessageId |
string |
A user-defined value that Service Bus can use to identify duplicate messages, if enabled. |
ReplyTo |
string |
The reply to queue address. |
Subject |
string |
The application-specific label which can be used in place of the Label metadata property. |
To |
string |
The send to address. |