AWS Lambda timeout warning not referring to the actual assigned timeout

[samkit-jain]

Environment

SaaS (https://sentry.io/)

Steps to Reproduce

1. Create an AWS Lambda function with a timeout of 900 seconds.
2. Create a Sentry project and the DSN to the lambda function code with timeout warning enabled.
3. Configure the function to exit after 200+ seconds.
4. Notice that Sentry raises a timeout warning.

Expected Result

No timeout warning as the execution run time is not at all near the configured 900s run time.

Actual Result

ServerlessTimeoutWarning issue created on Sentry

WARNING : Function is expected to get timed out. Configured timeout duration = 236 seconds.

Configured timeout duration should be 900 seconds. The same can also be seen in the Lambda function

Product Area

Issues

Link

No response

DSN

No response

Version

No response

[linear]

ENG-4685 AWS Lambda timeout warning not referring to the actual assigned timeout

[getsantry]

Auto-routing to @getsentry/product-owners-issues for triage ⏲️

[samkit-jain]

The AWS Lambda Python function is having the runtime version Python 3.12 and in the code, Sentry is initialised at the top of the index file like

import sentry_sdk
from sentry_sdk.integrations.aws_lambda import AwsLambdaIntegration

sentry_sdk.init(
    environment=os.environ["ENV"],
    dsn="DSN URI",
    integrations=[AwsLambdaIntegration(timeout_warning=True)],
)

requirements.txt include

boto3==1.34.113
sentry-sdk==2.19.2

[linear]

PY-1788 AWS Lambda timeout warning not referring to the actual assigned timeout

[szokeasaurusrex]

Hi @samkit-jain – thank you for reaching out.

I am a bit confused about the "Steps to Reproduce" you have provided, specifically item 3:

3. Configure the function to exit after 200+ seconds.

How exactly are you performing this configuration? In code somewhere? Please provide an example code snippet and/or a screenshot if possible, so I can understand what you are doing.

[samkit-jain]

Hi @szokeasaurusrex I am not doing any configuration. My AWS Lambda function normally exited after 203 seconds, so I just shared that to reproduce, one can try letting Lambda run for ~200 seconds.

[sentrivana]

Hey @samkit-jain, do I understand this correctly: You have a Lambda function that just exits on its own after ~200s and you have a way bigger timeout configured. The Lambda function finishes, but you see the TimeoutWarning even though it's nowhere near the configured timeout. Is that correct?

Is the TimeoutWarning raised roughly when the function finishes? If that's the case we need to figure out why it fires on thread shutdown. Does this happen consistently? Does it also happen in other Lambda functions, if you have some w/ Sentry?