Amazon AWS S3 browser-based upload using POST -

Question

I am building a web application that includes a file upload feature. My goal is to initiate upload from users directly to an S3 bucket. The strategy is to pre-sign a POST re

Answer 1

Found a solution: had to explicitly configure the s3 client to use Amazon's new signature v4. The error occurs since it defaults to an older version, causing the mismatch. Bit of a facepalm - at the time this wasn't written in boto3 docs, although folks at Amazon say it should be soon.

The method is simplified since it now returns exactly the fields required:

def s3_upload_creds(name):
    BUCKET = 'mybucket'
    REGION = 'us-west-1'
    s3 = boto3.client('s3', region_name=REGION, config=Config(signature_version='s3v4'))
    key = '${filename}'
    return s3.generate_presigned_post(
        Bucket = BUCKET,
        Key = key
    )

Which means the form can be easily generated:

  
    
  
  
    {{ creds }}
      

        {% for key, value in creds.fields.items() %}
          
        {% endfor %}
      File:
       

    
  

Cheers