Goth

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.

Installation

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

def deps do
  [{:goth, "~> 0.3.1"}]
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 "GCP_CREDENTIALS" ENV var:

config :goth, json: {:system, "GCP_CREDENTIALS"}
# where GCP_CREDENTIALS is the contents of the JSON credentials file

Or, via "GOOGLE_APPLICATION_CREDENTIALS" ENV var:

config :goth, json: {:system, "GOOGLE_APPLICATION_CREDENTIALS"}
# where GOOGLE_APPLICATION_CREDENTIALS is the path to JSON credentials file

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

Usage

Retrieve a token:

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"
  }