Ruby 2.2.0 Google Drive OAuth refresh - ruby

Question

I am trying to setup a command line backup app in ruby which accesses Google Drive using Oauth. I have set everything up in the account, created my Client ID and Secret. I seem to remember doing this before but cannot find the code. I used this answer before I think: Ruby google_drive gem oAuth2 saving
I have made a class to handle the Google Drive stuff then there is the applications main file which if given "hard" as an argument will do the initial setup where you have to copy and paste the link into the web browser in order to get a code which you can then paste into the CLI to get the initial access token and refresh token. This works and following these steps my list method (when not commented out) correctly lists everything in Google Drive. When I do the initial setup I am manually copying the access and refresh tokens to .access_token and .refresh_token, these are loading in the code fine.
What is not working, is refreshing the token which I understand I need to do otherwise it will expire, meaning I will have to go through the initial setup again which is obviously a pain (and not suitable for a CRON job). I am getting the following error when I run #auth.refresh!
/home/user/.rvm/gems/ruby-2.2.0/gems/signet-0.6.0/lib/signet/oauth_2/client.rb:947:in `fetch_access_token': Authorization failed. Server message: (Signet::AuthorizationError)
{
"error" : "invalid_grant"
}
from /home/user/.rvm/gems/ruby-2.2.0/gems/signet-0.6.0/lib/signet/oauth_2/client.rb:964:in `fetch_access_token!'
from /home/user/.rvm/gems/ruby-2.2.0/gems/signet-0.6.0/lib/signet/oauth_2/client.rb:981:in `refresh!'
from /home/user/Development/BackupBadger/Sources/Mechanisms/GoogleDriveMechanism.rb:62:in `connect'
from BackupBadger.rb:9:in `<main>'
I have had a look to see what it might be but am for the moment stuck on why this error is triggering when I can seemingly authenticate (since I can list all files on the drive)
My main file
$root=File.join('/home/user/Development/BackupBadger')
$sources=File.join($root,'Sources')
require File.join($sources,'Mechanisms','GoogleDriveMechanism.rb')
badger = BackupBadger::GoogleDriveMechanism.new
if ARGV[0] == "hard" then
badger.hard_setup
else
badger.connect
#badger.list
end
My class Google Drive
module BackupBadger
require 'google/api_client'
require 'google_drive'
require 'pp'
require File.join($sources,'Mechanism.rb')
class GoogleDriveMechanism
def initialize()
#client = Google::APIClient.new(
:application_name => 'Backup Badger',
:application_version => '0.0.1'
)
#access_token_path = File.join($root,'.access_token')
#refresh_token_path = File.join($root,'.refresh_token')
#auth = nil
#access_token = File.open(#access_token_path, "rb").read
#refresh_token = File.open(#refresh_token_path, "rb").read
#session = nil
#client_id = 'CLIENT_ID'
#client_secret = 'CLIENT_SECRET'
#redirect_uri = 'urn:ietf:wg:oauth:2.0:oob'
#scope = "https://www.googleapis.com/auth/drive " +
"https://spreadsheets.google.com/feeds/"
end
# Call this to do the initial setup, which requires pasting a url into a web broswer
def hard_setup
#auth = #client.authorization
#auth.client_id = #client_id
#auth.client_secret = #client_secret
#auth.scope = #scope
#auth.redirect_uri = #redirect_uri
print("1. Open this page:\n%s\n\n" % #auth.authorization_uri)
print("2. Enter the authorization code shown in the page: ")
#auth.code = $stdin.gets.chomp
#auth.fetch_access_token!
#access_token = #auth.access_token
system'clear'
print "Save your access token\n\n"
print #access_token
print "\nSave your refresh token\n\n"
print #auth.refresh_token
end
def connect
#auth = #client.authorization
#auth.client_id = #client_id
#auth.client_secret = #client_secret
#auth.scope = #scope
#auth.redirect_uri = #redirect_uri
#auth.refresh_token = #refresh_token
puts #access_token
puts #refresh_token
# Error is here
#auth.refresh!
#refresh_token = #auth.refresh_token
#access_token = #auth.access_token
File.write(#refresh_token_path, #refresh_token) if #refresh_token
File.write(#access_token_path, #access_token) if #access_token
puts #access_token
puts #refresh_token
end
def list
#session = GoogleDrive.login_with_oauth(#access_token)
for file in #session.files
p file.title
end
end
end
end

Answer 1

If the tl;dr is simply "how do I use a refresh token to get a new access token", then the answer is https://developers.google.com/accounts/docs/OAuth2WebServer#refresh
I won't paste the code coz it's likely to change, but in essence you simply POST to a Google URL and the JSON response is a shiny new access token.