Shan Shan - 4 years ago 484
Python Question

Boto3 to download all files from a S3 Bucket

I'm using boto3 to get files from s3 bucket. I need a similar functionality like

aws s3 sync

My current code is

import boto3
for key in list:
s3.download_file('my_bucket_name', key['Key'], key['Key'])

This is working fine, as long as the bucket has only files.
If a folder is present inside the bucket, its throwing an error

Traceback (most recent call last):
File "./test", line 6, in <module>
s3.download_file('my_bucket_name', key['Key'], key['Key'])
File "/usr/local/lib/python2.7/dist-packages/boto3/s3/", line 58, in download_file
extra_args=ExtraArgs, callback=Callback)
File "/usr/local/lib/python2.7/dist-packages/boto3/s3/", line 651, in download_file
extra_args, callback)
File "/usr/local/lib/python2.7/dist-packages/boto3/s3/", line 666, in _download_file
self._get_object(bucket, key, filename, extra_args, callback)
File "/usr/local/lib/python2.7/dist-packages/boto3/s3/", line 690, in _get_object
extra_args, callback)
File "/usr/local/lib/python2.7/dist-packages/boto3/s3/", line 707, in _do_get_object
with, 'wb') as f:
File "/usr/local/lib/python2.7/dist-packages/boto3/s3/", line 323, in open
return open(filename, mode)
IOError: [Errno 2] No such file or directory: 'my_folder/.8Df54234'

Is this a proper way to download a complete s3 bucket using boto3. How to download folders.

Answer Source

I got the same needs and create the following function that download recursively the files. The directories are created locally only if they contain files.

import boto3
import os

def download_dir(client, resource, dist, local='/tmp', bucket='your_bucket'):
    paginator = client.get_paginator('list_objects')
    for result in paginator.paginate(Bucket=bucket, Delimiter='/', Prefix=dist):
        if result.get('CommonPrefixes') is not None:
            for subdir in result.get('CommonPrefixes'):
                download_dir(client, resource, subdir.get('Prefix'), local, bucket)
        if result.get('Contents') is not None:
            for file in result.get('Contents'):
                if not os.path.exists(os.path.dirname(local + os.sep + file.get('Key'))):
                     os.makedirs(os.path.dirname(local + os.sep + file.get('Key')))
                resource.meta.client.download_file(bucket, file.get('Key'), local + os.sep + file.get('Key'))

The function is called that way:

def _start():
    client = boto3.client('s3')
    resource = boto3.resource('s3')
    download_dir(client, resource, 'clientconf/', '/tmp')
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