Using Lambda with Amazon MQ

Amazon MQ is a managed message broker service for Apache ActiveMQ and RabbitMQ. Lambda only supports Apache ActiveMQ. A message broker allows software applications and components to communicate using various programming languages, operating systems, and formal messaging protocols through either topic or queue event destinations.

Amazon MQ can also manage Amazon Elastic Compute Cloud (Amazon EC2) instances on your behalf by installing ActiveMQ brokers and by providing different network topologies and other infrastructure needs.

You can use a Lambda function to process records from your Amazon MQ message broker. Your function is triggered through an event source mapping, a Lambda resource that reads messages from your broker and invokes the function synchronously.

The Amazon MQ event source mapping has the following configuration restrictions:

• Authentication – Only the ActiveMQ SimpleAuthenticationPlugin is supported. User credentials associated with the broker are the only method of connection. For more information about authentication, see Messaging Authentication and Authorization for ActiveMQ in the Amazon MQ Developer Guide.

• Connection quota – Brokers have a maximum number of allowed connections per wire-level protocol. This quota is based on the broker instance type. For more information, see the Brokers section of Quotas in Amazon MQ in the Amazon MQ Developer Guide.

• Connectivity – You can create brokers in a public or private virtual private cloud (VPC). For private VPCs, your Lambda function needs access to the VPC to interact with the records. For more information, see Event source mapping API later in this topic.

• Event destinations – Only queue destinations are supported. However, you can use a virtual topic, which behaves as a topic internally while interacting with Lambda as a queue. For more information, see Virtual Destinations on the Apache ActiveMQ website.

• Network topology – Only one single-instance or standby broker is supported per event source mapping. Single-instance brokers require a failover endpoint. For more information about these broker deployment modes, see Amazon MQ Broker Architecture in the Amazon MQ Developer Guide.

• Protocols – Lambda consumes messages using the OpenWire/Java Message Service (JMS) protocol. No other protocols are supported. Within the JMS protocol, only TextMessage and BytesMessage are supported. For more information about the OpenWire protocol, see OpenWire on the Apache ActiveMQ website.

Lambda automatically supports the latest versions of ActiveMQ that Amazon MQ supports. For the latest supported versions, see Amazon MQ Release Notes in the Amazon MQ Developer Guide.

Note

By default, Amazon MQ has a weekly maintenance window for brokers. During that window of time, brokers are unavailable. For brokers without standby, Lambda cannot process any messages during that window.

Lambda consumer group

To interact with Amazon MQ, Lambda creates a consumer group which can read from your Amazon MQ brokers. The consumer group is created with the same ID as the event source mapping UUID.

Lambda will pull messages until it has processed a maximum of 6 MB, until timeout, or until the batch size is fulfilled. When configured, batch size determines the maximum number of items to retrieve in a single batch. Your batch is converted into a Lambda payload, and your target function is invoked. Messages are neither persisted nor deserialized. Instead, they are retrieved by the consumer group as a BLOB of bytes and are base64-encoded for a JSON payload.

Note

The maximum function invocation time is 14 minutes.

Lambda processes all incoming batches concurrently and automatically scales the concurrency to meet demands. You can monitor a given function's concurrency usage using the ConcurrentExecutions metric in Amazon CloudWatch. For more information about concurrency, see Managing concurrency for a Lambda function.

Example Amazon MQ record event

{
    "eventSource": "aws:amq",
    "eventSourceArn": "arn:aws:mq:us-west-2:112556298976:broker:test:b-9bcfa592-423a-4942-879d-eb284b418fc8",
    "messages": { [
            {
                "messageID": "ID:b-9bcfa592-423a-4942-879d-eb284b418fc8-1.mq.us-west-2.amazonaws.com-37557-1234520418293-4:1:1:1:1",
                "messageType": "jms/text-message",
                "data": "QUJDOkFBQUE=",
                "connectionId": "myJMSCoID",
                "redelivered": false,
                "destination": {
                   "physicalname": "testQueue" 
                }, 
                "timestamp": 1598827811958,
                "brokerInTime": 1598827811958,
                "brokerOutTime": 1598827811959
            },
            {
                "messageID": "ID:b-9bcfa592-423a-4942-879d-eb284b418fc8-1.mq.us-west-2.amazonaws.com-37557-1234520418293-4:1:1:1:1",
                "messageType":"jms/bytes-message",
                "data": "3DTOOW7crj51prgVLQaGQ82S48k=",
                "connectionId": "myJMSCoID1",
                "persistent": false,
                "destination": {
                   "physicalname": "testQueue" 
                }, 
                "timestamp": 1598827811958,
                "brokerInTime": 1598827811958,
                "brokerOutTime": 1598827811959
            }
        ]
    }
}

Execution role permissions

To read records from an Amazon MQ broker, your Lambda function needs the following permissions added to its execution role:

• mq:DescribeBroker

• secretsmanager:GetSecretValue

• ec2:CreateNetworkInterface

• ec2:DeleteNetworkInterface

• ec2:DescribeNetworkInterfaces

• ec2:DescribeSecurityGroups

• ec2:DescribeSubnets

• ec2:DescribeVpcs

Note

When using an encrypted customer managed key, add the kms:Decrypt permission as well.

Configuring a broker as an event source

Create an event source mapping to tell Lambda to send records from an Amazon MQ broker to a Lambda function. You can create multiple event source mappings to process the same data with multiple functions, or to process items from multiple sources with a single function.

To configure your function to read from Amazon MQ, create an MQ trigger in the Lambda console.

To create a trigger

1. Open the Functions page on the Lambda console.

2. Choose a function.

3. Under Function overview, choose Add trigger.

4. Choose a trigger type.

5. Configure the required options and then choose Add.

Lambda supports the following options for Amazon MQ event sources:

• MQ broker – Select an Amazon MQ broker.

• Batch size – Set the maximum number of messages to retrieve in a single batch.

• Queue name – Enter the Amazon MQ queue to consume.

• Source access configuration – Select the AWS Secrets Manager secret that stores your broker credentials.

• Enable trigger – Disable the trigger to stop processing records.

To enable or disable the trigger (or delete it), choose the MQ trigger in the designer. To reconfigure the trigger, use the event source mapping API operations.

Event source mapping API

To manage an event source with the AWS CLI or AWS SDK, you can use the following API operations:

• CreateEventSourceMapping

• ListEventSourceMappings

• GetEventSourceMapping

• UpdateEventSourceMapping

• DeleteEventSourceMapping

To create the event source mapping with the AWS Command Line Interface (AWS CLI), use the create-event-source-mapping command.

By default, Amazon MQ brokers are created with the PubliclyAccessible flag set to false. It is only when PubliclyAccessible is set to true that the broker is given a public IP address.

For full access with your event source mapping, your broker must either use a public endpoint or provide access to the VPC. To meet the Amazon VPC access requirements, you can do one of the following:

• Configure one NAT gateway per public subnet. For more information, see Internet and service access for VPC-connected functions.

• Create a connection between your Amazon VPC and Lambda. Your Amazon VPC must also connect to AWS STS and Secrets Manager endpoints. For more information, see Configuring interface VPC endpoints for Lambda.

The Amazon Virtual Private Cloud (Amazon VPC) security group rules that you configure should have the following settings at minimum:

• Inbound rules – For a broker without public accessibility, allow all traffic on all ports for the security group that's specified as your source. For a broker with public accessibility, allow all traffic on all ports for all destinations.

• Outbound rules – Allow all traffic on all ports for all destinations.

The Amazon VPC configuration is discoverable through the Amazon MQ API and does not need to be configured in the create-event-source-mapping setup.

The following example AWS CLI command creates an event source which maps a Lambda function named MQ-Example-Function to an Amazon MQ broker named ExampleMQBroker. The command also provides a Secrets Manager secret named ExampleMQBrokerUserPassword that stores the broker credentials.

aws lambda create-event-source-mapping \
--event-source-arn arn:aws:mq:us-east-1:12345678901:broker:ExampleMQBroker:b-b4d492ef-bdc3-45e3-a781-cd1a3102ecca \
--function-name MQ-Example-Function \
--source-access-configuration Type=BASIC_AUTH,URI=arn:aws:secretsmanager:us-east-1:12345678901:secret:ExampleMQBrokerUserPassword-xPBMTt \
--queues ExampleQueue 

You should see the following output:

{
    "UUID": "91eaeb7e-c976-1234-9451-8709db01f137",
    "BatchSize": 100,
    "EventSourceArn": "arn:aws:mq:us-east-1:12345678901:broker:ExampleMQBroker:b-b4d492ef-bdc3-45e3-a781-cd1a3102ecca",
    "FunctionArn": "arn:aws:lambda:us-east-1:12345678901:function:MQ-Example-Function",
    "LastModified": 1601927898.741,
    "LastProcessingResult": "No records processed",
    "State": "Creating",
    "StateTransitionReason": "USER_INITIATED",
    "Queues": [
        "ExampleQueue"
    ],
    "SourceAccessConfigurations": [
        {
            "Type": "BASIC_AUTH",
            "URI": "arn:aws:secretsmanager:us-east-1:12345678901:secret:ExampleMQBrokerUserPassword-xPBMTt"
        }
    ]
}

Using the update-event-source-mapping command, you can configure additional options such as how batches are processed and to specify when to discard records that can't be processed. The following example command updates an event source mapping to have a batch size of 2.

aws lambda update-event-source-mapping \
--uuid 91eaeb7e-c976-1234-9451-8709db01f137 \
--batch-size 2

You should see the following output:

{
    "UUID": "91eaeb7e-c976-1234-9451-8709db01f137",
    "BatchSize": 2,
    "EventSourceArn": "arn:aws:mq:us-east-1:12345678901:broker:ExampleMQBroker:b-b4d492ef-bdc3-45e3-a781-cd1a3102ecca",
    "FunctionArn": "arn:aws:lambda:us-east-1:12345678901:function:MQ-Example-Function",
    "LastModified": 1601928393.531,
    "LastProcessingResult": "No records processed",
    "State": "Updating",
    "StateTransitionReason": "USER_INITIATED"
} 

Updated settings are applied asynchronously and aren't reflected in the output until the process completes. To view the current status of your resource, use the get-event-source-mapping command.

aws lambda get-event-source-mapping \
--uuid 91eaeb7e-c976-4939-9451-8709db01f137

You should see the following output:

{
    "UUID": "91eaeb7e-c976-4939-9451-8709db01f137",
    "BatchSize": 2,
    "EventSourceArn": "arn:aws:mq:us-east-1:12345678901:broker:ExampleMQBroker:b-b4d492ef-bdc3-45e3-a781-cd1a3102ecca",
    "FunctionArn": "arn:aws:lambda:us-east-1:12345678901:function:MQ-Example-Function",
    "LastModified": 1601928393.531,
    "LastProcessingResult": "No records processed",
    "State": "Enabled",
    "StateTransitionReason": "USER_INITIATED"
}

Event source mapping errors

When a Lambda function encounters an unrecoverable error, your Amazon MQ consumer stops processing records. Any other consumers can continue processing, provided they don't encounter the same error. To determine the potential cause of a stopped consumer, check the StateTransitionReason field in the return details of your EventSourceMapping for one of the following codes:

ESM_CONFIG_NOT_VALID

The event source mapping configuration is not valid.

EVENT_SOURCE_AUTHN_ERROR

Lambda failed to authenticate the event source.

EVENT_SOURCE_AUTHZ_ERROR

Lambda does not have the required permissions to access the event source.

FUNCTION_CONFIG_NOT_VALID

The function's configuration is not valid.

Records also go unprocessed if they are dropped due to their size. The size limit for Lambda records is 6 MB. To redeliver messages upon function error, you can use a redelivery policy and dead-letter queue (DLQ) handling with Amazon MQ. For more information, see Message Redelivery and DLQ Handling on the Apache ActiveMQ website.