How to configure authorization mechanism inline with boto3

Question

I am using boto3 in aws lambda to fetch object in S3 located in Frankfurt Region. 

v4 is necessary. otherwise, the following error will return

"errorMessage": "An error occurred (InvalidRequest) when calling the GetObject operation: The authorization mechanism you have provided is not supported. Please use AWS4-HMAC-SHA256."

Realized ways to configure signature_version http://boto3.readthedocs.org/en/latest/guide/configuration.html

But since I am using AWS lambda, I do not have access to underlying configuration profiles 

The code of my AWS lambda function

from __future__ import print_function

import boto3

 

 

def lambda_handler (event, context):

    input_file_bucket = event["Records"][0]["s3"]["bucket"]["name"]

    input_file_key = event["Records"][0]["s3"]["object"]["key"]

    input_file_name = input_file_bucket+"/"+input_file_key

 

    s3=boto3.resource("s3")

    obj = s3.Object(bucket_name=input_file_bucket, key=input_file_key)

    response = obj.get()

    return event #echo first key valuesdf

Is that possible to configure signature_version within this code? use Session for example. Or is there any workaround on this?

Answer 1

Use a custom session and the Config from boto3.session rather than using a default session.

import boto3

import boto3.session

session = boto3.session.Session(region_name='eu-central-1')

s3client = session.client('s3', config= boto3.session.Config(signature_version='s3v4'))

s3client.get_object(Bucket='<Bkt-Name>', Key='S3-Object-Key')