Generate a file dynamically and upload it to S3

genfile_to_s3.py

import os
from io import BytesIO

import boto3

BUCKET = 'bucket-name'


def gen_int():
    a = 0
    b = 1
    while True:
        c = (a + b) % 10
        yield c
        a = b
        b = c


class FileObject:
    def __init__(self, size):
        self.offset = 0
        self.file_size = size
        self.gen = gen_int()

    def __enter__(self):
        return self

    def __exit__(self,  exc_type, exc_value, traceback):
        pass

    def read(self, size=-1):
        if self.offset >= self.file_size:
            return b''

        buffer = BytesIO()
        for _ in range(size):
            c = str(next(self.gen)).encode('ascii')
            buffer.write(c)

            self.offset += 1
            if self.offset >= self.file_size:
                break

        return buffer.getvalue()


def main():
    key_id = os.environ['AWS_ACCESS_KEY_ID']
    secret = os.environ['AWS_SECRET_ACCESS_KEY']
    token = os.environ['AWS_SESSION_TOKEN']
    s3 = boto3.client(
        's3',
        aws_access_key_id=key_id,
        aws_secret_access_key=secret,
        aws_session_token=token,
    )
    file_obj = FileObject(1000000)
    with file_obj as f:
        s3.upload_fileobj(f, BUCKET, 'myfile.txt')


main()