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[aws_lambda_events] EventBridgeEvent: missing field detail-type #1064

@pdesjardins90

Description

@pdesjardins90

EventBridgeEvent: missing field 'detail-type'

I've configured an EventBridge rule than triggers a lambda on a schedule, but I get a deserialization error on field 'detail-type' every time the lambda gets invoked.

CDK

new Rule(scope, 'MyRule', {
  schedule: Schedule.cron({ hour: '0', minute: '5' }),
  targets: [
    new LambdaFunction(lambdaAlias, {
      event: RuleTargetInput.fromObject({ myField: 'my value' })
    })
  ]
})

Lambda handler

use aws_lambda_events::eventbridge::EventBridgeEvent;
use lambda_runtime::tracing::{debug, info, init_default_subscriber};
use lambda_runtime::{Error, LambdaEvent, run, service_fn};
use serde::{Deserialize, Serialize};
use tokio::main;

#[derive(Debug, Serialize, Deserialize)]
struct MyPayload {
  #[serde(rename = "myField")]
  my_field: String
}

async fn handler(event: LambdaEvent<EventBridgeEvent<MyPayload>>) -> Result<(), Error> {
  debug!(?event, "My lambda triggered");
  let MyPayload { my_field } = event.payload.detail;
  info!("My field was {}", my_field);
  Ok(())
}

#[main]
async fn main() -> Result<(), Error> {
  init_default_subscriber();
  run(service_fn(handler)).await
}

Error

{
  "message": "Request payload deserialization into LambdaEvent<T> failed. The handler will not be called. Log at TRACE level to see the payload.",
  "error": "DeserializeError { inner: Error { path: Path { segments: [] }, original: Error(\"missing field `detail-type`\", line: 1, column: 22) } }"
}

Trace

{
  "message": "raw JSON event received from Lambda",
  "body": "{\"myField\":\"my value\"}"
}

State of investigation

From what I understand reading the docs, it seems "detail-type" might not be present all the time, but EventBridgeEvent makes it mandatory, hence this error I guess. Did not find a way to set it manually either. Looks like a bug in EventBridgeEvent?

Can you confirm my suspicions? Or am I missing something?

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