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Amazon EventBridge Pipes input transformation

Amazon EventBridge Pipes support optional input transformers when passing data to the enrichment and the target. You can use Input transformers to reshape the JSON event input payload to serve the needs of the enrichment or target service. For Amazon API Gateway and API destinations, this is how you shape the input event to the RESTful model of your API. Input transformers are modeled as an InputTemplate parameter. They can be free text, a JSON path to the event payload, or a JSON object that includes inline JSON paths to the event payload. For enrichment, the event payload is coming from the source. For targets, the event payload is what is returned from the enrichment, if one is configured on the pipe. In addition to the service-specific data in the event payload, you can use reserved variables in your InputTemplate to reference data for your pipe.

To access items in an array, use square bracket notation.

The following are sample InputTemplate parameters referencing an Amazon SQS event payload:

Static string

InputTemplate: "Hello, sender"

JSON Path

InputTemplate: <$.attributes.SenderId>

Dynamic string

InputTemplate: "Hello, <$.attributes.SenderId>"

Static JSON

InputTemplate: >
{
  "key1": "value1",
  "key2": "value2",
  "key3": "value3",
}

Dynamic JSON

InputTemplate: >
{
  "key1": "value1"
  "key2": <$.body.key>,
  "d": <aws.pipes.event.ingestion-time>
}

Using square bracket notation to access an item in an array:

InputTemplate: >
{
  "key1": "value1"
  "key2": <$.body.Records[3]>,
  "d": <aws.pipes.event.ingestion-time>
}

Reserved variables

Input templates can use the following reserved variables:

Input transform example

The following is an example Amazon EC2 event that we can use as our sample event.

{
  "version": "0",
  "id": "7bf73129-1428-4cd3-a780-95db273d1602",
  "detail-type": "EC2 Instance State-change Notification",
  "source": "aws.ec2",
  "account": "123456789012",
  "time": "2015-11-11T21:29:54Z",
  "region": "us-east-1",
  "resources": [
    "arn:aws:ec2:us-east-1:123456789012:instance/i-abcd1111"
  ],
  "detail": {
    "instance-id": "i-0123456789",
    "state": "RUNNING"
  }
}
		

Let's use the following JSON as our Transformer.

{
  "instance" : <$.detail.instance-id>,
  "state": <$.detail.state>,
  "pipeArn" : <aws.pipes.pipe-arn>,
  "pipeName" : <aws.pipes.pipe-name>,
  "originalEvent" : <aws.pipes.event.json>
}

The following will be the resulting Output:

{
  "instance" : "i-0123456789",
  "state": "RUNNING",
  "pipeArn" : "arn:aws:pipe:us-east-1:123456789012:pipe/example",
  "pipeName" : "example",
  "originalEvent" : {
    ... // commented for brevity
  }
}

Implicit body data parsing

The following fields in the incoming payload may be JSON-escaped, such as the Amazon SQS body object, or base64-encoded, such as the Kinesis data object. For both filtering and input transformation, EventBridge transforms these fields into valid JSON so sub-values can be referenced directly. For example, <$.data.someKey> for Kinesis.

To have the target receive the original payload without any additional metadata, use an input transformer with this body data, specific to the source. For example, <$.body> for Amazon SQS, or <$.data> for Kinesis. If the original payload is a valid JSON string (for example {"key": "value"}), then use of the input transformer with source specific body data will result in the quotes within the original source payload being removed. For example, {"key": "value"} will become "{key: value}" when delivered to the target. If your target requires valid JSON payloads (for example, EventBridge Lambda or Step Functions), this will cause delivery failure. To have the target receive the original source data without generating invalid JSON, wrap the source body data input transformer in JSON. For example, {"data": <$.data>}.

Implicit body parsing can also be used to dynamically populate values for most pipe target or enrichment parameters. For more information, see Dynamic path parameters

Common issues with transforming input

These are some common issues when transforming input in EventBridge pipes: