目标仅在通过 AWS CLI 调用 Lambda 时有效

Question

I have a hello-world test Lambda configured with:

• trigger: API Gateway
• destination: Amazon SQS. one queue for success, and another for failure.

import json

def lambda_handler(event, context):
    print("Received event: " + json.dumps(event))

    return {
        "statusCode": 200,
        "body": 'success'
    }

When I invoke the Lambda via the CLI, the message gets enqueued to the success queue as expected:

aws lambda invoke --function-name event-destinations --invocation-type Event --payload '{}' response.json

However, when I invoke the Lambda via the API Gateway, no messages are enqueued to either destination queue. I have Lambda Proxy Integration enabled. Cloudwatch metrics confirm that the invocation is successful (Invocations count goes up, Errors count does not). The following returns a 200 and and the expected response body from my Lambda code:

curl 'https://REDACTED.execute-api.us-east-1.amazonaws.com/api_trigger' \
--header 'Content-Type: application/json' \
--data-raw '{}'

Similarly, no messages are enqueued to either destination queue when I use the Test button in the Lambda console. edit: this is expected behavior per https://www.trek10.com/blog/lambda-destinations-what-we-learned-the-hard-way

Why would the destination behavior differ between these 3 invocations? I have set retry attempts to 0 for this test.

Answer 1

It seems there is a set of valid {trigger, destination} pairs, and {API Gateway, SQS} is not one of them. Being able to invoke the lambda from a given trigger is not sufficient to get the event passed along to the destination. AWS console doesn't enforce these pairing or raise warnings.

I referenced the chart from: https://www.trek10.com/blog/lambda-destinations-what-we-learned-the-hard-way/

I added an S3 trigger to my lambda, and the S3 events are published to the destination SQS queues without issue.

Answer 2

Lambda Destinations are only triggered for asynchronous invocations . In Lambda non-proxy (custom) integration, the backend Lambda function is invoked synchronously by default.

You can configure the Lambda function for a Lambda non-proxy integration to be invoked asynchronously by specifying 'Event' as the Lambda invocation type. This is done as follows:

In Integration Request, add an X-Amz-Invocation-Type header with a static value of 'Event'.

Quoting from here .