AWS Serverless - Lambda 同时支持 HTTP 和 Cloudwatch 计划事件

Question

My functions section in serverless.yml looks similar to:

functions: 
  MyLambda: 
    handler: handler.sayHello
    name: my-lambda-say-hello
    events:
      -  http: 
           path: /myPpath 
           method: post
           cors: true
      -  schedule: 
           name: my-schedule-event
           description: 'bla bla'
           rate: rate(10 minutes)
           input: 
             body: '{"name": "John"}'

My handler.sayHello lambda function looks like:

import json  

def sayHello(event, context):
  #Works for HTTP 
  print(json.loads(event['body'])['name']) 

  #Works for Cloudwatch schedule event 
  print(event['body']['name']

So basically I have a lambda function that gets a name and prints it.
This Lambda is triggered either by an HTTP request (I send the data as JSON in body) or by scheduled Cloudwatch event.

As you can see in my Lambda function, when I'm trying to extract the name property when it comes from an HTTP request, I need to json.loads() the event body object.
However, when it comes from a scheduled event, I don't need to json.loads() it at all.
Is it possible to somehow make my Lambda support both of those events, without toggling the json.loads() ?
Thanks!

Answer 1

The event payload of a Lambda function will vary depending on the invoking service. They are not the same across Cloudwatch, API Gateway, or other services like SNS, SQS, EventBridge, DynamoDB, S3 - and more.

Instead, you'll need to add logic which can conditionally extract the name (and other attributes) depending on the invoking service.

You can either wrap json.loads in a try/except block, or you could check if the event contains a requestContext key; which would indicate the function was triggered by an HTTP Request through API Gateway.