Stream and decompress a gzip file from S3

utils.py

import boto3
import zlib

def decompress_object(bucket, key, out_file):
    s3 = boto3.client("s3")
    body = s3.get_object(Bucket=bucket, Key=key)['Body']
    with open(out_file, "ab") as out:
        decompressor = zlib.decompressobj(zlib.MAX_WBITS|32)
        for chunk in body.iter_chunks():
            out.write(decompressor.decompress(chunk))
        decompressor.flush()