JWT使ってトークン取ってREST APIにリクエストしたりするやつ

google_api_jwt_test_service.rb

require 'jwt'

class GoogleApiJwtTestService
  def call
    claims = {
      iss: 'XXXX.iam.gserviceaccount.com',
      scope: 'https://www.googleapis.com/auth/XXXX',
      aud: 'https://www.googleapis.com/oauth2/v4/token',
      exp: (Time.zone.now + 3.minutes).to_i,
      iat: Time.zone.now.to_i
    }
    token = JWT.encode(claims, rsa_private, 'RS256')

    body = {
      assertion: token,
      grant_type: 'urn:ietf:params:oauth:grant-type:jwt-bearer'
    }

    response = RestClient.post(
      'https://www.googleapis.com/oauth2/v4/token',
      body
    )
    access_token = JSON.parse(response.body)['access_token']

    result = RestClient.get(
      'https://XXXXX...',
      { Authorization: "Bearer #{access_token}" }
    )
    ap result
  end

  private


  def rsa_private_key
    "-----BEGIN PRIVATE KEY-----\n...."
  end

  def rsa_private
    OpenSSL::PKey::RSA.new(rsa_private_key)
  end

  def rsa_public
    rsa_private.public_key
  end
end