Getting invocation statistics for a Lambda function.

Question

I have a moderate collection of Lambda functions that have been developed over a period of several years and I'm attempting a clean up and rationalisation. As part of this, I am attempting to run some reports on the frequency of invocation and success of these functions over time. I would like to do this programmatically - initially from the command line and subsequently from a Python program. I'm calling "aws cloudwatch get-metric-statistics" with input from a json file :  
  
"aws cloudwatch get-metric-statistics --cli-input-json file://get-stats.json"  
  
where the input file is:  
"{  
    "Namespace": "AWS/Lambda",  
    "MetricName": "Invocations",  
    "Dimensions": \[  
                {  
                    "Name": "FunctionName",  
                    "Value": "serverWatchdog"  
                },  
                {  
                    "Name": "Resource",  
                    "Value": "serverWatchdog"  
                }  
  
    ],  
    "StartTime": "2020-12-01T00:00:00",  
    "EndTime": "2020-12-05T00:00:00",  
    "Period": 360,  
    "Statistics": \[  
        "Average"  
    ],  
  
    "Unit": "Count"  
}"  
  
I know that this function is being called several times per hour - I can see it on the Cloudwatch console. But my CLI command always returns:  
  
{  
    "Label": "Invocations",  
    "Datapoints": \[]  
}  
  
Any suggestions as to what I'm doing wrong?  
  
TIA  
Martin

Answer

Thanks for that - it did fix it. It is an aspect of AWS that is not well documented!  
  
Martin

Answer

get rid of this section (and the leading comma):  
{  
"Name": "Resource",  
"Value": "serverWatchdog"  
}  
  
..and try that.  
  
the return is a little lacking, in that what it should say is "function not found"..but instead it looks like it's returning no data for that time range.

Getting invocation statistics for a Lambda function.

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