Google + Auth = Goth

A simple library to generate and retrieve OAuth2 tokens for use with Google Cloud Service accounts.

It can either retrieve tokens using service account credentials or from Google's metadata service for applications running on Google Cloud Platform.

1. Add Goth to your list of dependencies in mix.exs:

def deps do
  [{:goth, "~> 0.2.1"}]
end

2. Ensure Goth is started before your application:

def application do
  [applications: [:goth]]
end

3. Pass in your credentials json downloaded from your GCE account:

config :goth,
  json: "path/to/google/json/creds.json" |> File.read!

Or, via an ENV var:

config :goth, json: {:system, "GCP_CREDENTIALS"}

You can skip the last step if your application will run on a GCP or GKE instance with appropriate permissions.

Call Token.for_scope/1 passing in a string of scopes, separated by a space:

alias Goth.Token
{:ok, token} = Token.for_scope("https://www.googleapis.com/auth/pubsub")
#=>
  %Goth.Token{
    expires: 1453356568,
    token: "ya29.cALlJ4ICWRvMkYB-WsAR-CZnExE459PA7QPqKg5nei9y2T9-iqmbcgxq8XrTATNn_BPim",
    type: "Bearer"
  }