Package software.amazon.awscdk.services.lambda.destinations
Amazon Lambda Destinations Library
This library provides constructs for adding destinations to a Lambda function.
Destinations can be added by specifying the onFailure
or onSuccess
props when creating a function or alias.
Destinations
The following destinations are supported
- Lambda function
- SQS queue - Only standard SQS queues are supported for failure destinations, FIFO queues are not supported.
- SNS topic
- EventBridge event bus
Example with a SNS topic for successful invocations:
// An sns topic for successful invocations of a lambda function import software.amazon.awscdk.services.sns.*; Topic myTopic = new Topic(this, "Topic"); Function myFn = Function.Builder.create(this, "Fn") .runtime(Runtime.NODEJS_LATEST) .handler("index.handler") .code(Code.fromAsset(join(__dirname, "lambda-handler"))) // sns topic for successful invocations .onSuccess(new SnsDestination(myTopic)) .build();
Example with a SQS queue for unsuccessful invocations:
// An sqs queue for unsuccessful invocations of a lambda function import software.amazon.awscdk.services.sqs.*; Queue deadLetterQueue = new Queue(this, "DeadLetterQueue"); Function myFn = Function.Builder.create(this, "Fn") .runtime(Runtime.NODEJS_LATEST) .handler("index.handler") .code(Code.fromInline("// your code")) // sqs queue for unsuccessful invocations .onFailure(new SqsDestination(deadLetterQueue)) .build();
See also Configuring Destinations for Asynchronous Invocation.
Invocation record
When a lambda function is configured with a destination, an invocation record is created by the Lambda service when the lambda function completes. The invocation record contains the details of the function, its context, and the request and response payloads.
The following example shows the format of the invocation record for a successful invocation:
{ "version": "1.0", "timestamp": "2019-11-24T23:08:25.651Z", "requestContext": { "requestId": "c2a6f2ae-7dbb-4d22-8782-d0485c9877e2", "functionArn": "arn:aws:lambda:sa-east-1:123456789123:function:event-destinations:$LATEST", "condition": "Success", "approximateInvokeCount": 1 }, "requestPayload": { "Success": true }, "responseContext": { "statusCode": 200, "executedVersion": "$LATEST" }, "responsePayload": "<data returned by the function here>" }
In case of failure, the record contains the reason and error object:
{ "version": "1.0", "timestamp": "2019-11-24T21:52:47.333Z", "requestContext": { "requestId": "8ea123e4-1db7-4aca-ad10-d9ca1234c1fd", "functionArn": "arn:aws:lambda:sa-east-1:123456678912:function:event-destinations:$LATEST", "condition": "RetriesExhausted", "approximateInvokeCount": 3 }, "requestPayload": { "Success": false }, "responseContext": { "statusCode": 200, "executedVersion": "$LATEST", "functionError": "Handled" }, "responsePayload": { "errorMessage": "Failure from event, Success = false, I am failing!", "errorType": "Error", "stackTrace": [ "exports.handler (/var/task/index.js:18:18)" ] } }
Destination-specific JSON format
- For SNS/SQS (
SnsDestionation
/SqsDestination
), the invocation record JSON is passed as theMessage
to the destination. - For Lambda (
LambdaDestination
), the invocation record JSON is passed as the payload to the function. - For EventBridge (
EventBridgeDestination
), the invocation record JSON is passed as thedetail
in the PutEvents call. The value for the event fieldsource
islambda
, and the value for the event fielddetail-type
is either 'Lambda Function Invocation Result - Success' or 'Lambda Function Invocation Result – Failure', depending on whether the lambda function invocation succeeded or failed. The event fieldresource
contains the function and destination ARNs. See AWS Events for the different event fields.
Auto-extract response payload with lambda destination
The responseOnly
option of LambdaDestination
allows to auto-extract the response payload from the
invocation record:
// Auto-extract response payload with a lambda destination Function destinationFn; Function sourceFn = Function.Builder.create(this, "Source") .runtime(Runtime.NODEJS_LATEST) .handler("index.handler") .code(Code.fromAsset(join(__dirname, "lambda-handler"))) // auto-extract on success .onSuccess(LambdaDestination.Builder.create(destinationFn) .responseOnly(true) .build()) .build();
In the above example, destinationFn
will be invoked with the payload returned by sourceFn
(responsePayload
in the invocation record, not the full record).
When used with onFailure
, the destination function is invoked with the error object returned
by the source function.
Using the responseOnly
option allows to easily chain asynchronous Lambda functions without
having to deal with data extraction in the runtime code.
-
ClassDescriptionUse an Event Bridge event bus as a Lambda destination.Use a Lambda function as a Lambda destination.A fluent builder for
LambdaDestination
.Options for a Lambda destination.A builder forLambdaDestinationOptions
An implementation forLambdaDestinationOptions
Use a SNS topic as a Lambda destination.Use a SQS queue as a Lambda destination.