Unable to pass aws.events.event.json in input transformer template

Question

I am using eventbridge to trigger batch run through custom put-events request(using boto3). My request is as follows :-
```python
INPUT_DATA = {
    "data":[List], # i.e. data key has list value where each list item is dict
    "sample_key":"sample_string_value"
}
client = boto3.client("events")
response = client.put_events(Entries=[
    {
        "Source": "my.app.com",
        "Detail": json.dumps(INPUT_DATA),
        "DetailType":"sample-type",
        "EventBusName":"my-event-bus"
    }
])
```
In order to pass data from eventbridge to batch, I have following input transformer template :-
```terraform
input_paths = {
}

input_template = <"
      }
    ]
  }
}
EOF
```
where `aws.events.event.json` is pre-defined variable for event payload(i.e. detail key value) as *string*.

When I run the script, I am able to see metric for `triggeredRule`with `1` but invocation for batch run fails i.e. `failedInvocations` count as `1` is also seen in the metrics. At the same time, if replace `aws.events.event.json` with `aws.events.rule-arn` or `aws.events.rule-name` or `aws.events.event.ingestion-time`, batch run is triggered and correct values of latter variables is also seen in job descriptions's environment section.

I tried to refer similar issue [here](https://repost.aws/questions/QUCMU-UIYoThyQqlkCn2sWEQ/eventbridge-input-transformer-example-doesnt-work) but it does not seem solve the issue.

Can someone suggest where is the issue in above input transformer while using `aws.events.event.json` ? Is it due format of `INPUT_DATA` that I am sending ? Would appreciate any hint.

Thanks

Answer

Not sure on this but can you try this template and see if it works?

```
input_template = <
      }
    ]
  }
}
EOF
```

I've removed the quotes around `` to avoid an escaping issues like the ones mentioned in the last line of this doc https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-transform-target-input.html#eb-transform-input-issues

> EventBridge doesn't escape values extracted by Input Path, when populating the Input Template for a target.

EventBridge also doesn't unescape to when `aws.events.event.json` is `"{\"a\":\"b\"}"`, the outcoming transformation may make `"Value": ""` to `"Value": ""{\"a\":\"b\"}""`. This will be an invalid JSON and lead to failureInvocation metric.

If this wasn't the issue, then I'd recommend checking if there's any other unescaped quotes in the  event payload. The easiest way would be to send your events to CloudWatch Log target and inspect the event there.

Unable to pass aws.events.event.json in input transformer template

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