In the following example, we specify that the
compute function should be triggered whenever there are messages in the given SQS Queue.
The ARN for the queue can be specified as a string, the reference to the ARN of a resource by logical ID, or the import of an ARN that was exported by a different service or CloudFormation stack.
sqs event will hook up your existing SQS Queue to a Lambda function. Serverless won't create a new queue for you.
functions: compute: handler: handler.compute events: # These are all possible formats - sqs: arn:aws:sqs:region:XXXXXX:MyFirstQueue - sqs: arn: Fn::GetAtt: - MySecondQueue - Arn - sqs: arn: Fn::ImportValue: MyExportedQueueArnId - sqs: arn: Fn::Join: - ':' - - arn - aws - sqs - Ref: AWS::Region - Ref: AWS::AccountId - MyOtherQueue
Setting the BatchSize
For the SQS event integration, you can set the
batchSize, which effects how many SQS messages can be included in a single Lambda invocation. The default
10. The max
10000 for a standard queue,
10 for a FIFO queue.
You can also set
maximumBatchingWindow to standard queues to specify the maximum amount of time in seconds to gather records before invoking the function. The max
You can set
ReportBatchItemFailures to let your function return a partial success result if one or more messages in the batch have failed.
Check AWS documentation for more details.
functions: compute: handler: handler.compute events: - sqs: arn: arn:aws:sqs:region:XXXXXX:myQueue batchSize: 10 maximumBatchingWindow: 60 functionResponseType: ReportBatchItemFailures
Setting filter patterns
This configuration allows customers to filter event before lambda invocation. It accepts up to 5 filter patterns by default and up to 10 with quota extension. If one event matches at least 1 pattern, lambda will process it.
For more details and examples of filter patterns, please see the AWS event filtering documentation
Note: Serverless only sets this property if you explicitly add it to the
sqs configuration (see an example below). The following example will only process records where field
a is equal to 1 or 2.
functions: onlyOneOrTwo: handler: handler.preprocess events: - sqs: arn: arn:aws:sqs:region:XXXXXX:myQueue filterPatterns: - a: [1, 2]
Setting the Maximum Concurrency
The maximum concurrency setting limits the number of concurrent instances of the function that an Amazon SQS event source can invoke. The minimum limit of concurrent functions that the event source can invoke is
2, and the maximum is
1000. To turn off maximum concurrency, leave this field empty.
For more details, see the AWS SQS max concurrency documentation.
functions: onlyOneOrTwo: handler: handler.preprocess events: - sqs: arn: arn:aws:sqs:region:XXXXXX:myQueue maximumConcurrency: 250
The Serverless Framework will automatically configure the most minimal set of IAM permissions for you. However you can still add additional permissions if you need to. Read the official AWS documentation for more information about IAM Permissions for SQS events.
Deploying SQS queues
The examples above show how to consume messages from an existing SQS queue. To create an SQS queue in
serverless.yml, you can either write custom CloudFormation, or you can use Lift.
Lift is a Serverless Framework plugin that simplifies deploying pieces of applications via "constructs". Lift can be installed via:
serverless plugin install -n serverless-lift
We can use the
queue construct to deploy an SQS queue with its Lambda consumer:
constructs: my-queue: type: queue worker: handler: handler.compute plugins: - serverless-lift
queue construct deploys:
- An SQS queue
workerLambda function: this function processes messages sent to the queue.
- An SQS "dead letter queue": this queue stores all the messages that failed to be processed.
queue construct documentation to find a complete example with code, and to learn how to configure the batch size, retries and other options.