How to choose an AWS profile when using boto3 to connect to CloudFront

I am using the Boto 3 python library, and want to connect to AWS CloudFront. I need to specify the correct AWS Profile (AWS Credentials), but looking at the official documentation, I see no way to specify it.

I am initializing the client using the code: client = boto3.client('cloudfront')

However, this results in it using the default profile to connect. I couldn't find a method where I can specify which profile to use.

I think the docs aren't wonderful at exposing how to do this. It has been a supported feature for some time, however, and there are some details in this pull request.

So there are three different ways to do this:

Option A) Create a new session with the profile

    dev = boto3.session.Session(profile_name='dev')

Option B) Change the profile of the default session in code

    boto3.setup_default_session(profile_name='dev')

Option C) Change the profile of the default session with an environment variable

    $ AWS_PROFILE=dev ipython
    >>> import boto3
    >>> s3dev = boto3.resource('s3')

Do this to use a profile with name 'dev':

session = boto3.session.Session(profile_name='dev')
s3 = session.resource('s3')
for bucket in s3.buckets.all():
    print(bucket.name)