Upload Gzip file using Boto3 - python-3.x

Question

i am trying to upload files to S3 before that i am trying to Gzip files, if you see the code below, the files uploaded to the S3 have no change in the size, so i am trying to figure out if i have missed something.
import gzip
import shutil
from io import BytesIO
def upload_gzipped(bucket, key, fp, compressed_fp=None, content_type='text/plain'):
"""Compress and upload the contents from fp to S3.
If compressed_fp is None, the compression is performed in memory.
"""
if not compressed_fp:
compressed_fp = BytesIO()
with gzip.GzipFile(fileobj=compressed_fp, mode='wb') as gz:
shutil.copyfileobj(fp, gz)
compressed_fp.seek(0)
bucket.upload_fileobj(
compressed_fp,
key,
{'ContentType': content_type, 'ContentEncoding': 'gzip'})
Courtesy Link for the source
And this is how i am using this fucntion, so basically reading files as stream from SFTP and then trying to Gzip them and then write them to S3.
with pysftp.Connection(host_name, username=user, password=password, cnopts=cnopts, port=int(port)) as sftp:
list_of_files = sftp.listdir('{}{}'.format(base_path, file_path))
is_file_found = False
for file_name in list_of_files:
if entity_name in str(file_name.lower()):
is_file_found = True
flo = BytesIO()
# Step 1: Read File Using SFTP as input Stream
sftp.getfo('{}{}/{}'.format(base_path, file_path, file_name), flo)
s3_destination_key = '{}/{}'.format(s3_path, file_name)
# Step 2: Write files to desitination S3
logger.info('Moving file to S3 {} '.format(s3_destination_key))
# Creating a bucket resource to use bucket object for file upload
input_bucket_object = S3.Bucket(environment_config['S3_INBOX_BUCKET'])
flo.seek(0)
upload_gzipped(input_bucket_object, s3_destination_key, flo)

Answer 1

It seems like the upload_gzipped function uses shutil.copyfileobj incorrectly.
Looking at https://docs.python.org/3/library/shutil.html#shutil.copyfileobj shows that you put the source first, and destination second.
Also, you're just writing your object to a gzipped object without ever actually compressing it.
You need to compress fp into a Gzip object, then upload that specific object to S3.
I'd recommend not using that gist from github as it seems wrong.