Download file from AWS S3 using Python

Question

I am trying to download a file from Amazon S3 bucket to my local using the below code but I get an error saying "Unable to locate credentials"

Given below is the code I have written:

from boto3.session import Session
import boto3

ACCESS_KEY = 'ABC'
SECRET_KEY = 'XYZ'

session = Session(aws_access_key_id=ACCESS_KEY,
              aws_secret_access_key=SECRET_KEY)
s3 = session.resource('s3')
your_bucket = s3.Bucket('bucket_name')

for s3_file in your_bucket.objects.all():
    print(s3_file.key) # prints the contents of bucket

s3 = boto3.client ('s3')

s3.download_file('your_bucket','k.png','/Users/username/Desktop/k.png')

Could anyone help me on this?

Answer 1

From an example in the official documentation, the correct format is:

import boto3

s3 = boto3.client('s3', aws_access_key_id=... , aws_secret_access_key=...)
s3.download_file('BUCKET_NAME', 'OBJECT_NAME', 'FILE_NAME')

You can also use a file-like object opened in binary mode.

s3 = boto3.client('s3', aws_access_key_id=... , aws_secret_access_key=...)
with open('FILE_NAME', 'wb') as f:
    s3.download_fileobj('BUCKET_NAME', 'OBJECT_NAME', f)
    f.seek(0)

---

The code in question uses s3 = boto3.client ('s3'), which does not provide any credentials.

The format for authenticating a client is shown here:

import boto3
client = boto3.client(
    's3',
    aws_access_key_id=ACCESS_KEY,
    aws_secret_access_key=SECRET_KEY,
    aws_session_token=SESSION_TOKEN,
)

# Or via the Session
session = boto3.Session(
    aws_access_key_id=ACCESS_KEY,
    aws_secret_access_key=SECRET_KEY,
    aws_session_token=SESSION_TOKEN,
)

---

And lastly you can also re-use the authenticated session you created to get the bucket, and then download then file from the bucket.

from boto3.session import Session
import boto3

ACCESS_KEY = 'ABC'
SECRET_KEY = 'XYZ'

session = Session(aws_access_key_id=ACCESS_KEY,
              aws_secret_access_key=SECRET_KEY)

# session is authenticated and can access the resource in question 
session.resource('s3')
    .Bucket('bucket_name')
    .download_file('k.png','/Users/username/Desktop/k.png')

Answer 2

For others trying to download files from AWS S3 looking for a more user-friendly solution with other industrial-strength features, check out https://github.com/d6t/d6tpipe. It abstracts the S3 functions into a simpler interface. It also supports directory sync, uploading files, permissions and many other things you need to sync files from S3 (and ftp).

import d6tpipe
api = d6tpipe.api.APILocal() # keep permissions locally for security

settings = \
{
    'name': 'my-files',
    'protocol': 's3',
    'location': 'bucket-name',
    'readCredentials' : {
        'aws_access_key_id': 'AAA',
        'aws_secret_access_key': 'BBB'
    }
}

d6tpipe.api.create_pipe_with_remote(api, settings)

pipe = d6tpipe.Pipe(api, 'my-files')
pipe.scan_remote() # show all files
pipe.pull_preview() # preview
pipe.pull(['k.png']) # download single file
pipe.pull() # download all files

pipe.files() # show files
file=open(pipe.dirpath/'k.png') # access file

Answer 3

You can setup your AWS profile with awscli to avoid introduce your credentials in the file. First add your profile:

aws configure --profile account1

Then in your code add:

aws_session = boto3.Session(profile_name="account1")
s3_client = aws_session.client('s3')