How do I authorize a service account for Google Calendar API in Ruby?

Question

How do I authorize a service account for Google Calendar API in Ruby? I tried the quick start guide, but it crashed.

https://developers.google.com/calendar/quickstart/ru

Answer 1

OK I found a way.

https://developers.google.com/api-client-library/ruby/auth/service-accounts

require 'google/apis/calendar_v3'
require 'googleauth'

# Get the environment configured authorization
scopes =  ['https://www.googleapis.com/auth/calendar']
authorization = Google::Auth.get_application_default(scopes)

# Clone and set the subject
auth_client = authorization.dup
auth_client.sub = 'myemail@mydomain.com'
auth_client.fetch_access_token!

# Initialize the API
service = Google::Apis::CalendarV3::CalendarService.new
service.authorization = auth_client

# Fetch the next 10 events for the user
calendar_id = 'primary'
response = service.list_events(calendar_id,
                               max_results: 10,
                               single_events: true,
                               order_by: 'startTime',
                               time_min: Time.now.iso8601)
puts 'Upcoming events:'
puts 'No upcoming events found' if response.items.empty?
response.items.each do |event|
  start = event.start.date || event.start.date_time
  puts "- #{event.summary} (#{start})"
end

And

>set GOOGLE_APPLICATION_CREDENTIALS=client_secrets.json

C:\Users\Chloe\workspace>ruby quickstart.rb
Upcoming events:
- Test (2018-05-17)
- SSL Certificate for CMS (2019-02-13)

But I wonder where it saves the refresh token and access token? All I have to do now is make it work for ephemeral file systems like Heroku and store the tokens in the database.

Answer 2

For anyone still looking this is what worked for me:

require 'google/apis/calendar_v3'
require 'googleauth'

scope = 'https://www.googleapis.com/auth/calendar'

authorizer = Google::Auth::ServiceAccountCredentials.make_creds(
  json_key_io: File.open('/path/to/creds.json'),
  scope: scope)

authorizer.fetch_access_token!

service = Google::Apis::CalendarV3::CalendarService.new
service.authorization = authorizer

calendar_id = 'primary'
response = service.list_events(calendar_id,
                               max_results: 10,
                               single_events: true,
                               order_by: 'startTime',
                               time_min: Time.now.iso8601)
puts 'Upcoming events:'
puts 'No upcoming events found' if response.items.empty?
response.items.each do |event|
  start = event.start.date || event.start.date_time
  puts "- #{event.summary} (#{start})"
end

The trick was finding the docs for the google-auth-library-ruby https://github.com/googleapis/google-auth-library-ruby