Boto3 generate presinged url does not work - amazon-s3

Question

Here is my code that I use to create a s3 client and generate a presigned url, which are some quite standard codes. They have been up running in the server for quite a while. I pulled the code out and ran it locally in a jupyter notebook
def get_s3_client():
return get_s3(create_session=False)
def get_s3(create_session=False):
session = boto3.session.Session() if create_session else boto3
S3_ENDPOINT = os.environ.get('AWS_S3_ENDPOINT')
if S3_ENDPOINT:
AWS_ACCESS_KEY_ID = os.environ['AWS_ACCESS_KEY_ID']
AWS_SECRET_ACCESS_KEY = os.environ['AWS_SECRET_ACCESS_KEY']
AWS_DEFAULT_REGION = os.environ["AWS_DEFAULT_REGION"]
s3 = session.client('s3',
endpoint_url=S3_ENDPOINT,
aws_access_key_id=AWS_ACCESS_KEY_ID,
aws_secret_access_key=AWS_SECRET_ACCESS_KEY,
region_name=AWS_DEFAULT_REGION)
else:
s3 = session.client('s3', region_name='us-east-2')
return s3
s3 = get_s3_client()
BUCKET=[my-bucket-name]
OBJECT_KEY=[my-object-name]
signed_url = s3.generate_presigned_url(
'get_object',
ExpiresIn=3600,
Params={
"Bucket": BUCKET,
"Key": OBJECT_KEY,
}
)
print(signed_url)
When I tried to download the file using the url in the browser, I got an error message and it says "The specified key does not exist." I noticed in the error message that my object key becomes "[my-bucket-name]/[my-object-name]" rather than just "[my-object-name]".
Then I used the same bucket/key combination to generate a presigned url using aws cli, which is working as expected. I found out that somehow the s3 client method (boto3) inserted [my-object-name] in front of [my-object-name] compared to the aws cli method. Here are the results
From s3.generate_presigned_url()
https://[my-bucket-name].s3.us-east-2.amazonaws.com/[my-bucket-name]/[my-object-name]?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAV17K253JHUDLKKHB%2F20210520%2Fus-east-2%2Fs3%2Faws4_request&X-Amz-Date=20210520T175014Z&X-Amz-Expires=3600&X-Amz-SignedHeaders=host&X-Amz-Signature=5cdcc38e5933e92b5xed07b58e421e5418c16942cb9ac6ac6429ac65c9f87d64
From aws cli s3 presign
https://[my-bucket-name].s3.us-east-2.amazonaws.com/[my-object-name]?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAYA7K15LJHUDAVKHB%2F20210520%2Fus-east-2%2Fs3%2Faws4_request&X-Amz-Date=20210520T155926Z&X-Amz-Expires=3600&X-Amz-SignedHeaders=host&X-Amz-Signature=58208f91985bf3ce72ccf884ba804af30151d158d6ba410dd8fe9d2457369894
I've been working on this and searching for solutions for day and half and I couldn't find out what was wrong with my implementation. I guess it might be that I ignored some basic but important settings to create a s3 client using boto3 or something else. Thanks for the help!

Answer 1

Ok, myth is solved, I shouldn't provide the endpoint_url=S3_ENDPOINT param when I create the s3 client, boto3 will figure it out. After i removed it, everything works as expected.