#!/usr/bin/env python3

import boto3

session = boto3.Session(profile_name='the_profile')
s3 = session.client('s3')
url = s3.generate_presigned_url(
    ClientMethod='get_object',
    Params={ 'Bucket':'bucket_name', 'Key':'object_name'},
    ExpiresIn=604800) # 7 days