class Google::Auth::ServiceAccountJwtHeaderCredentials

Authenticates requests using Google's Service Account credentials via JWT Header.

This class allows authorizing requests for service accounts directly from credentials from a json key file downloaded from the developer console (via 'Generate new Json Key'). It is not part of any OAuth2 flow, rather it creates a JWT and sends that as a credential.

cf [Application Default Credentials](cloud.google.com/docs/authentication/production)

Constants

AUTH_METADATA_KEY
EXPIRY
JWT_AUD_URI_KEY
SIGNING_ALGORITHM
TOKEN_CRED_URI

Attributes

project_id[R]
quota_project_id[R]

Public Class Methods

make_creds(*args) click to toggle source

make_creds proxies the construction of a credentials instance

make_creds is used by the methods in CredentialsLoader.

By default, it calls new with 2 args, the second one being an optional scope. Here's the constructor only has one param, so we modify make_creds to reflect this.

# File lib/googleauth/service_account.rb, line 152
def self.make_creds *args
  new json_key_io: args[0][:json_key_io]
end
new(options = {}) click to toggle source

Initializes a ServiceAccountJwtHeaderCredentials.

@param json_key_io [IO] an IO from which the JSON key can be read

# File lib/googleauth/service_account.rb, line 159
def initialize options = {}
  json_key_io = options[:json_key_io]
  if json_key_io
    @private_key, @issuer, @project_id, @quota_project_id =
      self.class.read_json_key json_key_io
  else
    @private_key = ENV[CredentialsLoader::PRIVATE_KEY_VAR]
    @issuer = ENV[CredentialsLoader::CLIENT_EMAIL_VAR]
    @project_id = ENV[CredentialsLoader::PROJECT_ID_VAR]
    @quota_project_id = nil
  end
  @project_id ||= CredentialsLoader.load_gcloud_project_id
  @signing_key = OpenSSL::PKey::RSA.new @private_key
end

Public Instance Methods

apply(a_hash, opts = {}) click to toggle source

Returns a clone of a_hash updated with the authoriation header

# File lib/googleauth/service_account.rb, line 187
def apply a_hash, opts = {}
  a_copy = a_hash.clone
  apply! a_copy, opts
  a_copy
end
apply!(a_hash, opts = {}) click to toggle source

Construct a jwt token if the JWT_AUD_URI key is present in the input hash.

The jwt token is used as the value of a 'Bearer '.

# File lib/googleauth/service_account.rb, line 178
def apply! a_hash, opts = {}
  jwt_aud_uri = a_hash.delete JWT_AUD_URI_KEY
  return a_hash if jwt_aud_uri.nil?
  jwt_token = new_jwt_token jwt_aud_uri, opts
  a_hash[AUTH_METADATA_KEY] = "Bearer #{jwt_token}"
  a_hash
end
updater_proc() click to toggle source

Returns a reference to the apply method, suitable for passing as a closure

# File lib/googleauth/service_account.rb, line 195
def updater_proc
  lambda(&method(:apply))
end

Protected Instance Methods

new_jwt_token(jwt_aud_uri, options = {}) click to toggle source

Creates a jwt uri token.

# File lib/googleauth/service_account.rb, line 202
def new_jwt_token jwt_aud_uri, options = {}
  now = Time.new
  skew = options[:skew] || 60
  assertion = {
    "iss" => @issuer,
    "sub" => @issuer,
    "aud" => jwt_aud_uri,
    "exp" => (now + EXPIRY).to_i,
    "iat" => (now - skew).to_i
  }
  JWT.encode assertion, @signing_key, SIGNING_ALGORITHM
end