ash_authentication/documentation/tutorials/google-quickstart.md

Google Quick Start Guide

This is a very quick tutorial on how to configure Google authentication in your application using the default oauth2 strategy in ash.

First you'll need a registered application in Google Cloud, in order to get your OAuth 2.0 Client credentials.

1. On the Cloud's console Quick access section select APIs & Services, then Credentials
2. Click on + CREATE CREDENTIALS and from the dropdown select OAuth client ID
3. From the google developers console, we will need: client_id & client_secret

Next we configure our resource to use google credentials:

defmodule MyApp.Accounts.User do
  use Ash.Resource, extensions: [AshAuthentication]

  attributes do
    ...
  end

  authentication do
    strategies do
      oauth2 :google do
        client_id "123abc..."
        redirect_uri {:ok, "123abc..."}
        client_secret fn -> {:ok, "123abc..."} end
        site MyApp.Secrets
      end
    end
  end
end

Please check the guide on how to properly configure your Secrets Then we need to define an action that will handle the oauth2 flow, for the google case it is :register_with_google it will handle both cases for our resource, user registration & login.

defmodule MyApp.Accounts.User do
  use Ash.Resource, extensions: [AshAuthentication]
  # ...
  actions do
    create :register_with_google do
      argument :user_info, :map, allow_nil?: false
      argument :oauth_tokens, :map, allow_nil?: false
      upsert? true
      upsert_identity :email

      change AshAuthentication.GenerateTokenChange

      # Required if you have the `identity_resource` configuration enabled.
      # change AshAuthentication.Strategy.OAuth2.IdentityChange

      change fn changeset, _ctx ->
        user_info = Ash.Changeset.get_argument(changeset, :user_info)
        changeset
          |> Ash.Changeset.change_attribute(:google_info, user_info)
          # you could upsert custom user attributes from the given google's user_info
          # |> Ash.Changeset.change_attribute(:email, user_info["email"])
          # |> Ash.Changeset.change_attribute(:name, user_info["name"])
          # |> Ash.Changeset.change_attribute(:portrait, user_info["picture"])
      end
    end
  end
  # ...
end