如何在 lambda 中解析来自 AWS 事件规则的输入？

Question

如果我在事件规则中使用输入......我应该如何在 lambda 中解析它？

现在我有：

  MyJobScheduledRule:
    Type: AWS::Events::Rule
    Properties:
      Description: Scheduled Rule
      ScheduleExpression: !Sub "rate(${IntervalMinutes} minutes)"
      State: "ENABLED"
      Targets:
        - Id: "MyJobLambda"
          Arn: !GetAtt MyJobLambda.Arn
          Input: "\"{\\\"key\\\":\\\"value\\\"}\"

使用以下 lambda：

public class MyJobLambda implements RequestHandler<Map<String, String>, Void>  {
  private static Logger LOGGER = LoggerFactory.getLogger(MyJobLambda.class);

  @Override
  public Void handleRequest(Map<String, String> event, Context context) {

    LOGGER.debug("MyJob got value {} from input", event.get("key"));

    return null;
  }

}

但我得到以下运行时异常：

An error occurred during JSON parsing: java.lang.RuntimeException
java.lang.RuntimeException: An error occurred during JSON parsing
Caused by: java.io.UncheckedIOException: com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `java.util.LinkedHashMap` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('
{
    "key": "value"
}

我也尝试过使用 POJO 作为 lambda 的输入。有什么想法吗？

Answer 1

使用 ScheduledEvent 对象，并解析事件的详细信息字段

import com.amazonaws.services.lambda.runtime.events.ScheduledEvent;
public class MyJobLambda implements RequestHandler<Map<String, String>, Void>  {
  private static Logger LOGGER = LoggerFactory.getLogger(MyJobLambda.class);

  @Override
  public Void handleRequest(ScheduledEvent event, Context context) {

    LOGGER.debug("MyJob got value {} from input", mapScheduledEventDetail(event.getDetail());

    return null;
  }

 private String mapScheduledEventDetail(Map<String,Object> detailObject) {
       return ParserUtil.parseObjectToJson(detailObject.get("clientId"));
    }

}

Answer 2

import os
import boto3
import json

#EVENT JSON PARSER (SYED)
def lambda_handler(event, context):
print('starting a new execution')
print('## ENVIRONMENT VARIABLES')
print(os.environ)
AMI = os.environ['AMI']
print('printing os variable AMI')
print(AMI)
print('#########################')
print('PRINTING EVENT')
print(event)
#return event
print('taking message payload from event')
#messagepayload = event['Records'][0]['Sns']['Message']
#the event[] gives a simple string
#the json.loads converts that string into a json/python dictionary that you can use
#[0] denotes first part of the array
messagepayload = json.loads(event['Records'][0]['Sns']['Message'])
print(messagepayload)
#key2 represents a key in the message payload json 
#next we take value for the key named as key2
key2value = messagepayload['key2']
print(key2value)
return key2value
print('END OF EXECUTION')