Uploading objects with presigned URLs

Copy the contents of the script and save it as “put-only-url.py” file. To use the following examples, replace the user input placeholders with your own information (such as your file name).

import argparse
import boto3
from botocore.exceptions import ClientError

def generate_presigned_url(s3_client, client_method, method_parameters, expires_in):
    """
    Generate a presigned Amazon S3 URL that can be used to perform an action.
    
    :param s3_client: A Boto3 Amazon S3 client.
    :param client_method: The name of the client method that the URL performs.
    :param method_parameters: The parameters of the specified client method.
    :param expires_in: The number of seconds the presigned URL is valid for.
    :return: The presigned URL.
    """
    try:
        url = s3_client.generate_presigned_url(
            ClientMethod=client_method,
            Params=method_parameters,
            ExpiresIn=expires_in
        )
    except ClientError:
        print(f"Couldn't get a presigned URL for client method '{client_method}'.")
        raise
    return url

def main():
    parser = argparse.ArgumentParser()
    parser.add_argument("bucket", help="The name of the bucket.")
    parser.add_argument(
        "key", help="The key (path and filename) in the S3 bucket.",
    )
    parser.add_argument(
        "--region", help="The AWS region where the bucket is located.", default="us-east-1"
    )
    parser.add_argument(
        "--content-type", help="The content type of the file to upload.", default="application/octet-stream"
    )
    args = parser.parse_args()
    
    # Create S3 client with explicit region configuration
    s3_client = boto3.client("s3", region_name=args.region)
    
    # Optionally set signature version if needed for older S3 regions
    # s3_client.meta.config.signature_version = 's3v4'
    
    # The presigned URL is specified to expire in 1000 seconds
    url = generate_presigned_url(
        s3_client, 
        "put_object", 
        {
            "Bucket": args.bucket, 
            "Key": args.key,
            "ContentType": args.content_type  # Specify content type
        }, 
        1000
    )
    print(f"Generated PUT presigned URL: {url}")

if __name__ == "__main__":
    main()

To generate a PUT presigned URL for uploading a file, run the following script with your bucket name and desired object path.

The following command uses example values. Replace the user input placeholders with your own information.

python put-only-url.py amzn-s3-demo-bucket <object-path> --region us-east-1 --content-type application/octet-stream

The script will output a PUT presigned URL:

Generated PUT presigned URL: https://amzn-s3-demo-bucket.s3.amazonaws.com/object.txt?AmazonAccessKeyId=AKIAIOSFODNN7EXAMPLE&Signature=vjbyNxybdZaMmLa%2ByT372YEAiv4%3D&Expires=1741978496

You can now upload the file using the generated presigned URL with curl. Make sure to include the same content type that was used when generating the URL:

curl -X PUT -T "path/to/your/local/file" -H "Content-Type: application/octet-stream" "generated-presigned-url"

If you specified a different content type when generating the URL, make sure to use that same content type in the curl command.