Fog: Authenticate to Google Compute Engine (GCE) using an instance's service account

gistfile1.rb

require 'fog'
require 'google/api_client'

APP_NAME = "my-app"
APP_VERSION = "1.0.0"
GOOGLE_PROJECT = "my-project-808"

client = Google::APIClient.new({
  application_name: APP_NAME,
  application_version: APP_VERSION,
  user_agent: "fog/#{Fog::VERSION}"
})
client.authorization = Google::APIClient::ComputeServiceAccount.new
client.authorization.fetch_access_token!

options = {
  :provider => 'google',
  :google_project => GOOGLE_PROJECT,
  :google_client => client
}

connection = Fog::Compute.new(options)
networks = connection.networks.all
p networks