Error while creating an cloudwatchMetricFilter with Cloudformation

Question

Hi together,
I'm trying to create an Cloudwatch Metric Filter with Cloudformation:

```
myCWMetric:
    Type: AWS::Logs::MetricFilter
    Properties:
      LogGroupName: /aws/lambda/mybackend-list
      FilterPattern: "[...,uri=%contacts%, duration,]"
      MetricTransformations:
        - MetricValue: "$.duration"
          MetricNamespace: mybackend-list/apiDurations
          MetricName: ContactMediaDuration
          Unit: Milliseconds
```

The ErrorMesage which is Cloudformation is throwing is the following:

```
Resource handler returned message: "Invalid request provided: AWS::Logs::MetricFilter. Invalid metric transformation: metric value $.duration must be a valid number
```
anyone have an idea how to solve this issue?

Thx :-)
Oliver

Andrii S · Accepted Answer

Hello.

The error message suggests that the $.duration is not being interpreted as a valid number, which might be happening because of the filter pattern or a mismatch with the actual log event format.

Ensure that the duration placeholder correctly matches the actual logs. For example, if your log line is something like:

```
some-text uri=/contacts/123 duration=456
```

**Then your filter pattern might look something like:**

```
FilterPattern: "... uri=%contacts% duration=$[duration]"
```

Regards, Andrii

Error while creating an cloudwatchMetricFilter with Cloudformation

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