When Lambda runs a function, it passes a context object to the handler. This object provides methods and properties that provide information about the invocation, function, and execution environment. One of the context methods is getRemainingTimeInMillis() which returns the number of milliseconds left before the execution times out. Using the method, we can schedule a callback to be actioned before the function times out and and perform whatever task needed ie preemptively log the timeout event. The possibility of false positive could happen for the 50 ms reserved, but that probably outweighs not having any error logs when the function does time out.
Cost: Milliseconds of execution time & single cloudwatch log event. See information on pricing - https://aws.amazon.com/lambda/pricing/
A large indicator of timeouts is by looking at a function’s Max Duration metric.
Cost: Pay for cloudwatch alarm (metric already exists). See information on pricing - https://aws.amazon.com/cloudwatch/pricing/
Guaranteed receiving a 'Task timed out after...' log for when a function times out, therefore creating a cloudwatch log metric for the filter pattern and cloudwatch alarm to be trigger on a certain count.
Cost: Pay for both cloudwatch alarm and custom metric. See information on pricing - https://aws.amazon.com/cloudwatch/pricing/
- AWS Documentation: Lambda context object in Node.js
- AWS Documentation: Cloudwatch Alarms
- AWS Documentation: Creating metrics from log events using filters
export AWS_PROFILE=<profile_name>yarn run installyarn run deployCheck serverless output for api endpoints to test.
curl -X GET https://<API_ID>.<REGION>.execute-api.amazonaws.com/dev/logserverless logs -f log curl -X GET https://<API_ID>.<REGION>.execute-api.amazonaws.com/dev/durationAlarmcurl -X GET https://<API_ID>.<REGION>.execute-api.amazonaws.com/dev/metricFilteryarn run remove