在 AWS Lambda 中解析 SQS 消息触发器

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问题描述

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我收到有关 S3 存储桶上传的通知，以便将消息放入 SQS 队列.SQS 队列触发 lambda 函数.我正在尝试提取从触发 lambda 函数的 SQS 消息中上传的文件的名称.打印到 CloudWatch 日志时，我的 SQS 事件记录如下所示:

I have a notification on an S3 bucket upload to place a message in an SQS queue. The SQS queue triggers a lambda function. I am trying to extract the name of the file that was uploaded from the SQS message which triggers the lambda function. My SQS event record looks like this when printed to the CloudWatch logs:

{
"Records": [
    {
        "eventVersion": "2.1",
        "eventSource": "aws:s3",
        "awsRegion": "eu-west-2",
        "eventTime": "2020-04-05T13:55:30.970Z",
        "eventName": "ObjectCreated:Put",
        "userIdentity": {
            "principalId": "A2RFWU4TTDGK95"
        },
        "requestParameters": {
            "sourceIPAddress": "HIDDEN"
        },
        "responseElements": {
            "x-amz-request-id": "024EF2A2E94BD5CA",
            "x-amz-id-2": "P/5p5mDwfIu29SeZcNo3wjJaGAiM4yqBqp4p3gOfLVPeZhf+w5sRjnxsost3BuYub1FVf7tuMFs9KoC98+fwSI9NrT5WbjYq"
        },
        "s3": {
            "s3SchemaVersion": "1.0",
            "configurationId": "ImageUpload",
            "bucket": {
                "name": "HIDDEN",
                "ownerIdentity": {
                    "principalId": "A2RFWU4TTDGK95"
                },
                "arn": "arn:aws:s3:::HIDDEN"
            },
            "object": {
                "key": "activity1.png",
                "size": 41762,
                "eTag": "9e1645a32c2948139a90e75522deb5ab",
                "sequencer": "005E89E354A986B50D"
            }
        }
    }
]
}

使用此代码:

import boto3
rek = boto3.client('rekognition')

def test(event, context):
    for record in event['Records']:
       print ("test")
       payload=record["body"]
       fullpayload=str(payload)
       print(fullpayload)

使用 ['s3]['object]['key'] 访问有效负载字符串上的文件名 'activity1.png' 给我这个错误:

Using ['s3]['object]['key'] to access the filename 'activity1.png' on the payload string gives me this error:

's3': KeyError
Traceback (most recent call last):

如何从 lambda 函数访问文件名?

How can i access the file name from the lambda function?

推荐答案

如果这就是我的想法:S3 对象创建事件 -->SQS <-- lambda 轮询，我也遇到了这个.我使用了 s3 put 示例测试，还使用了来自 sqs 消息的轮询进行了另一个测试.当它不是在测试中实际读取队列时，我遇到了问题.

If this is what I think it is: the S3 Object Create events --> SQS <-- lambda polls, I ran into this also. I was using the s3 put example test and also used my poll from sqs message to make another test. When it came from actually reading the queue not in a test, I had issues.

print(event) 的输出实际上是整个事件的 json，如下所示:

The output of print(event) is actually json of the entire event like below:

    {   'Records': 
        [   
            {
            'messageId': '61155c1d-aaaa-aaaa-aaaa-aaaaaaaaaaaa',
            'receiptHandle': 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaalF5156pb+aSqhRWbEY1XWIAVpingcBgOM8/uv1pIgfVXtfNRwzjtoCcInH6doGo9C38uWG7V48uEzpiAPr6Ao2IkXn5IEQKgxXzgelT5FtW3gpwhsQ3fvsFZdZNkMj2YiBHpdJ9QDgfmjFOWmqEJL+LWHUyksdAHxqVZMFrdaS1Tmno3Xni7DMBg1Ed+HpHkBmAVOWssDfM25lC1RNUivXj8i3iI/gD0yBlCttA4aioAlYNZ0txBrkm8aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaML+jK3JcKXiaslbu+JNZaB7hwevHRNsGIQ2MLuRhX+eHD4BN',
            'body': 
                '{"Records":    
                  [
                    {   
                    "eventVersion":"2.1",
                    "eventSource":"aws:s3",
                    "awsRegion":"us-east-1",
                    "eventTime":"2021-02-24T00:30:07.549Z",
                    "eventName":"ObjectCreated:Put",
                    "userIdentity":{"principalId":"AWS:AROAAAAAAAAAA:Rolehere"},
                    "requestParameters":{"sourceIPAddress":"x.x.x.x"},"responseElements":{"x-amz-request-id":"860A2aaaaaaaB19","x-amz-id-2":"J8epzX+FGaLsliSYSiJaaaaaaaaaaaaaETviVcrVCD/FsQjVLNBJgcv8v/PIh37Y9waaaaaaaaaaaaaaaaoUkoqhlr"},
                    "s3":
                        {"s3SchemaVersion":"1.0",
                        "configurationId":"New arrival",                    
                        "bucket":
                        {"name":"molly-bucketname","ownerIdentity":{"principalId":"A2aaaaaaFMND3"},"arn":"arn:aws:s3:::molly-bucketname"},
                        "object":{"key":"dietcokeofevil.mp3","size":420049,"eTag":"bf153e303affbb6e54feb0a233879d4d","versionId":"B2WJZpLLvpWA4nXP5T5QjVZY09qpnHKa","sequencer":"0060359E131BAA52C0"}
                        }
                    }
                   ]
                 }',
            'attributes': {
                'ApproximateReceiveCount': '1',
                'SentTimestamp': '1614126612305',
                'SenderId': 'AIDAJHaaaaaaaaaaJEBU',
                'ApproximateFirstReceiveTimestamp': '1614126612308'
            },
            'messageAttributes': {},
            'md5OfMessageAttributes': None,
            'md5OfBody': 'c752a7082100075786323ff7e5cdfc26',
            'eventSource': 'aws:sqs',
            'eventSourceARN': 'arn:aws:sqs:us-east-1:#########:queuename',
            'awsRegion': 'us-east-1'
            }
        ]
    }

当 s3 没有传送到 lambda 时，lambda 正在从队列中读取 - 您在 put 示例中实际看到的 json 似乎有一个包装器.如果您尝试在 lambda 中将打印的事件(上图)添加到您的测试中，则会出现 json 错误.我们需要解析初始 Records json &对身体然后 json.load thebody" - 然后从中解析我们的 s3 信息.

When an s3 doesn't deliver to lambda, lambda is reading from the queue - it seems like there's a wrapper around the json you actually see in the put examples. If you tried to add the printed event (above) to your test in lambda, it will json error. We need to parse the initial Records json & for the body then json.load the "body"- then parse our s3 info out of it.

import json
import boto3


def lambda_handler(event, context):
    
    #Loops through every file uploaded
    for record in event['Records']:
        #pull the body out & json load it
        jsonmaybe=(record["body"])
        jsonmaybe=json.loads(jsonmaybe)
        
        #now the normal stuff works
        bucket_name = jsonmaybe["Records"][0]["s3"]["bucket"]["name"]
        print(bucket_name)
        key=jsonmaybe["Records"][0]["s3"]["object"]["key"]
        print(key)

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