upload_images.py

import boto3
from boto3.s3.transfer import TransferConfig

BUCKET = "<your bucket from SAM template>"
REGION = "<your region>"
PROFILE = "<your profile>"


def upload_to_s3(file_name, key, bucket=BUCKET, region=REGION):

    # Multipart upload config
    config = TransferConfig(
        multipart_threshold=1024 * 25,
        max_concurrency=10,
        multipart_chunksize=1024 * 25,
        use_threads=True,
    )

    # I have separate profiles in aws so I have to define one here
    # in order to authenticate myself to my account
    # If you do not have multiple profiles, just remove the argument
    session = boto3.Session(profile_name=PROFILE)

    s3 = session.client("s3", region_name=region)

    # Upload file to S3
    s3.upload_file(file_name, bucket, key, Config=config)


upload_to_s3("local file", "key on s3")