Google OAuth callback phase executed twice

I've been stuck on this issue for a couple of days, and i am a loss here. I have implemented the google login via OAuth 2 for our website, it's working perfectly on my computer (local environment) on any browser, but when i deploy to our staging environment, it works only with google chrome. We use the devise 2.2.8 gem to handle authentification coupled with google-oauth2 0.2.6 to handle interaction with google login. One of the thing that concerns me is that our authentification process happen on 2 different subdomain such as:

1. Landing on webpage (en.mywebsite.com)
2. Click on Login with Gmail
3. Request made to our server
4. Redirection on google consent screen
5. Callback url for authentification (my.website.com)

Once the user is authentified, he will only browse on my.website.com but originally before being authentified he was on a different subdomain. So i was wondering if there could be some issue on a session level during the authentification ?

Here are the log when i want to authentify myself via Google Login on our staging environment on google chrome:

Jul 16 11:36:44 (google_oauth2) Request phase initiated.

Jul 16 11:36:44 (google_oauth2) Callback phase initiated.

Jul 16 11:36:45 method=GET path=/users/auth/google_oauth2/callback format=html controller=authentification/omniauth action=google_oauth2 status=302 duration=49.96 view=0.00 location=http://my.website.com/ params={"state"=>"e6a565c411170cfcbc62d0209970bd39842aae090671a95a", "code"=>"4/Ib0zrAHgAVNWli9RwJsXf9g7edcVlx96xVLmxCB4Eoc", "controller"=>"authentification/omniauth", "action"=>"google_oauth2"}

Jul 16 11:36:46 method=GET path=/ format=html controller=my/dashboard action=index status=200 duration=839.57 view=160.90 params={"controller"=>"my/dashboard", "action"=>"index"}

---

Here are the log when i want to authentify myself via Google Login on our staging environment on Safari:

Jul 16 11:24:21 (google_oauth2) Request phase initiated.

Jul 16 11:24:22 (google_oauth2) Callback phase initiated.

Jul 16 11:24:23 method=GET path=/users/auth/google_oauth2/callback format=html controller=authentification/omniauth action=google_oauth2 status=401 duration=0.77 view=0.00 params={"state"=>"05e6567e2443eb5766c77a271d60a767a568b32491ce852c", "code"=>"4/yNlgCDyI71mmYoT48BpWIJNnbaKzUhy7bclIxGHqJdo", "controller"=>"authentification/omniauth", "action"=>"google_oauth2"}

Jul 16 11:24:23 (google_oauth2) Callback phase initiated.

Jul 16 11:24:23 (google_oauth2) Authentication failure! invalid_credentials: OAuth2::Error, invalid_grant: Code was already redeemed.

Jul 16 11:24:23 { Jul 16 11:24:23 "error" : "invalid_grant", Jul 16 11:24:23 "error_description" : "Code was already redeemed." Jul 16 11:24:23 }

Because the callback phase is initiated twice, and the token from google oauth is for a uniq usage, the second callback obviously fails.

I have one file omniauth.rb file under initialiser folders, to place Omniauth in the middleware stack:

Rails.application.config.middleware.use OmniAuth::Builder do
  provider :google_oauth2, "google-id", "secret", { scope: "email, profile, gmail.readonly, calendar"}
end

I know some people got the same issue as me when they defined Omniauth twice because they defined it in both omniauth.rb file and devise.rb so i made sure it defined only once.