Please configure your AWS credentials, either through environment variables or
~/.boto config file.

For example:

export AWS_ACCESS_KEY_ID=XXXXXXXXXXXXXX
export AWS_SECRET_ACCESS_KEY=XXXXXXXXXXXXXXXXXXXXXXXXXXXXX

or in ~/.boto (make sure you chmod 600 ~/.boto):

[Credentials]
aws_access_key_id = XXXXXXXXXXXXXX
aws_secret_access_key = XXXXXXXXXXXXXXXXXXXXXXXXXXXXX