class Aws::CredentialProviderChain

def env_credentials(options)
  key =    %w(AWS_ACCESS_KEY_ID     AMAZON_ACCESS_KEY_ID     AWS_ACCESS_KEY)
  secret = %w(AWS_SECRET_ACCESS_KEY AMAZON_SECRET_ACCESS_KEY AWS_SECRET_KEY)
  token =  %w(AWS_SESSION_TOKEN     AMAZON_SESSION_TOKEN)
  Credentials.new(envar(key), envar(secret), envar(token))
end