我需要将img从Postman上传到lambda到S3

Question

我正在尝试通过 Postman 的表单上传，然后尝试通过 lambda fn 接收该图像，然后将其存储在 s3 中。

问题是：显示了文件名，但是当我下载它时，我得到了

不支持文件类型

我已授予访问 S3 和 lambda 的权限。我是 lambda 函数的新手，并试图弄清楚如何做这些事情

代码：

import json
import boto3
import base64

s3_client = boto3.client('s3')
BUCKET_NAME = 'u'
last_value = None

def lambda_handler(event, context):
global last_value
print(json.dumps(event))

    # Check if the event is from API Gateway
    if 'httpMethod' in event:
        if event['httpMethod'] == 'POST':
            try:
                headers = event.get('headers', {})
                body = event.get('body', '')
                
                # If the body is base64 encoded, decode it
                if event.get('isBase64Encoded', False):
                    body = base64.b64decode(body)
                
                # Extract file name from headers
                file_name = headers.get('file-name')
                
                if not file_name:
                    raise ValueError("Missing 'file-name' header")
                
                # The body should contain binary data directly if it's a file upload
                # Upload to S3
                s3_client.put_object(
                    Bucket=BUCKET_NAME,
                    Key=file_name,
                    Body=body.split('image/jpeg\r\n\r\n')[1],  # Use the body directly as it should be binary data
                    ContentType='image/jpeg'  # Ensure this matches the actual content type
                )
                
                last_value = file_name
                print('Passed value:', last_value)
                return {
                    'statusCode': 200,
                    'body': json.dumps(f'The passed value is: {last_value}')
                }
            except Exception as e:
                return {
                    'statusCode': 500,
                    'body': json.dumps(f'Error uploading file: {str(e)}')
                }
        
        elif event['httpMethod'] == 'GET':
            try:
                # Fetch the image from S3
                file_name = last_value  # Get the last uploaded file name
                if not file_name:
                    raise ValueError("No file has been uploaded yet.")
                
                s3_response = s3_client.get_object(Bucket=BUCKET_NAME, Key=file_name)
                image_data = s3_response['Body'].read()
                
                return {
                    'statusCode': 200,
                    'isBase64Encoded': True,
                    'headers': {
                        'Content-Type': 'image/jpeg'  # or 'image/png' based on your use case
                    },
                    'body': base64.b64encode(image_data).decode('utf-8')
                }
            except Exception as e:
                return {
                    'statusCode': 500,
                    'body': json.dumps(f'Error fetching image: {str(e)}')
                }
    
    # Check if the event is from S3
    elif 'Records' in event and event['Records'][0]['eventSource'] == 'aws:s3':
        for record in event['Records']:
            bucket_name = record['s3']['bucket']['name']
            object_key = record['s3']['object']['key']
            print(f"File uploaded to bucket: {bucket_name}, Key: {object_key}")
            
        return {
            'statusCode': 200,
            'body': json.dumps('S3 Event processed successfully.')
        }

Answer 1

更好的方法是这个用例。调用对 API Gateway 的调用，该调用将反过来调用 Lambda 函数，该函数调用创建预签名 URL 的 S3 操作。

使用该 URL 将图像直接上传到 S3 存储桶。比尝试通过 Lambda 函数强制将图像从 Postman 传输到 S3 好得多。