EventBridge event not received. What am I doing wrong?

Serverless Framework
1

Hi there,

I use event bridge to send events to labmda functions. I have this working perfectly between different micro-services (different sls projects). However, when I throw an event with a listener in the same sls project, I’m not receiving it! no error nothing. It all worked fine sls offline with the serverless-offline-aws-eventbridge but once I deploy to aws… nothing :sob:. Please tell me what I’m doing wrong?

I omitted some code here and there. But I provide all the relevant info. In the example below, I call an API call through http (POST /service/items), which creates a bunch of serviceItems in DynamoDB and publishes an event called… serviceItemsCreated. Then a listener listens to this event and does some additional magic.

serverless.yml

custom:
  eventBusArn: arn:aws:events:${env:REGION}:${env:AWS_ACCOUNT_ID}:event-bus/waitless-dev-frank

provider:
  name: aws
  runtime: nodejs12.x
  region: ${env:REGION} // eu-central-1
  environment:
    EVENT_BUS_ARN: ${self:custom.eventBusArn}
    REGION: ${env:REGION}
  iam:
    role:
      statements:
        - Effect: Allow
          Action:
            - events:putEvents
          Resource:
            - ${self:custom.eventBusArn}

functions:
  # API
  serviceApi:
    handler: src/app.handler
    events:
      - http:
          path: /
          method: any
  serviceItemsCreated:
    handler: src/ws.sendEventToServiceConnections
    events:
      - eventBridge:
          eventBus: ${self:custom.eventBusArn}
          pattern:
            source:
              - waitless.api.service
            detail-type:
              - serviceItemsCreated

src/app.ts

does some generic/security magic and includes ./routes/create-service-items.ts

src/routes/create-service-items.ts

import express, { Request, Response } from 'express';
import { publishEvent } from '../libs/events';

router.post('/service/items', async (req: Request, res: Response) => {

	// perform some checks
	// generate some serviceItems
	// do some db mutation

    // publish event serviceItemsCreated
    await publishEvent({
      source: 'waitless.api.service',
      detailType: Types.EventType.serviceItemsCreated,
      detail: JSON.stringify(serviceItems)
    });
    
    res.status(201).send(serviceItems);
  }
);

src/libs/events.ts

I put some logging in this file so I can check in cloudwatch what is happening.

import { CustomError, Types } from '@frank/external-libs';
import AWS from 'aws-sdk';

const EVENT_BUS_ARN = process.env.EVENT_BUS_ARN;
const REGION = process.env.REGION;

console.log('libs / events', 'EVENT_BUS_ARN', EVENT_BUS_ARN);
console.log('libs / events', 'REGION', REGION);

const config = {
  region: REGION,
}

const eventBridge = new AWS.EventBridge(config);

export const publishEvent = async (event: Types.Event) => {

  console.log('services / events', 'publish event', event);

  const params = {
    Entries: [
      {
        EventBusName: EVENT_BUS_ARN,
        Source: event.source,
        DetailType: event.detailType,
        Detail: event.detail,
      },
    ],
  };

  console.log('services / events', 'params', params);
  
  try {
    await eventBridge.putEvents(params).promise();
    console.log('yay');
    return;
  } catch (e) {
    console.error(e);
    throw new CustomError(500, 'publish event failed', 'EVENTBRIDGE-PublishEventFailed', e);
  }  

}

and finally… the place where that event should arrive:

src/ws.ts

// WS Send Event to Service Connections
export const sendEventToServiceConnections = async (event: EventBridgeEvent<Types.EventType, Types.ServiceItem[]>) => {

	// well pretty much irrelevant cause it never gets called i'll just put a console log here
	console.log('here');

}

Hopefully, you have found my error already and made me a happy person. Nevertheless, I will show how I attemt to get to that last part:

I know, long read. Sorry about that. Do you know what i’m doing wrong? Please advice.

Thank you, Frank

2

OK, I have solved the above topic but I can’t seem to close the topic. Maybe interesting for future reference / people who do the same as me: event detail must be a JSON object, and not a JSON array.

Perhaps interesting to know for the people maintaining serverless-offline-aws-eventbridge this works differently online.