How to create OmniAuth strategy aliases

omniauth_alias.rb

# lib/omniauth-adwords-oauth2.rb
require "omniauth-google-oauth2"

class AdwordsOauth2 < OmniAuth::Strategies::GoogleOauth2
  option :name, 'adwords_oauth2'
end

# config/initializers/omniauth.rb
require "omniauth-adwords-oauth2"

Rails.application.config.middleware.use OmniAuth::Builder do
  provider :adwords_oauth2, ENV['GOOGLE_API_CLIENT_ID'], ENV['GOOGLE_API_CLIENT_SECRET'], {
    scope: "https://adwords.google.com/api/adwords/" # could also be adwords-sandbox.google.com
  }
end

OmniAuth.config.logger = Rails.logger

You actually should be able to do this:

Rails.application.config.middleware.use OmniAuth::Builder do
  provider :google_oauth2, ENV['GOOGLE_API_CLIENT_ID'], ENV['GOOGLE_API_CLIENT_SECRET'], {
    scope: "https://adwords.google.com/api/adwords/" # could also be adwords-sandbox.google.com,
    name: :adwords_oauth2
  }
end