Event generating cloudwatch logs but not triggering lambda

Question

New to aws, wrote a few lambda functions a few months ago  that are triggered via external events sent to aws.  Those are working fine. 
However, I created a few others in the past few days to accept other types of events. I get the cloudwatch logs but the lambda function does not appear to get executed.

secondabhi_aws · Accepted Answer

I assume you are trying to invoke lambda function through cloudwatch events. If so, then did you check, if resource permission has been added to lambda function for that newly created rule. Most of the cases, this gets missed and even if event would match, it won't be able to invoke lambda function.

For your reference, here is the cloudformation snippet, how you'd add lambda resource permissions for the event rule:

rLambdaInvokePermission:
          Type: 'AWS::Lambda::Permission'
          Properties:
            FunctionName: !Ref myLambdaFunction
            Action: 'lambda:InvokeFunction'
            Principal: events.amazonaws.com
            SourceArn: !GetAtt rEventRule.Arn

Second thing, I'd check, if event pattern is matching exactly what's defined in event rule or not. You can do that by testing the event rule pattern and see if it matches or not.

Also, I'd suggest you to take a look at this [re:Post thread](https://repost.aws/knowledge-center/eventbridge-lambda-not-triggered), which talks in details about the same topic.

Hoe you find this information helpful.

Comment here if you have additional questions, happy to help.

Abhishek

Event generating cloudwatch logs but not triggering lambda

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