FcmRuby gems lets your ruby backend send notification to android and ios via Firebase Cloud Messaging. It's enable to send to specific devices.
Add this line to your application's Gemfile:
gem 'fcm_ruby'
And then execute:
$ bundle install
Or install it yourself as:
$ gem install fcm_ruby
# api_keys can get by google-auth (https://github.com/googleapis/google-auth-library-ruby)
# See https://firebase.google.com/docs/reference/fcm/rest/v1/projects.messages for message structure
# message argument also supports array (send to multiple devices)
fcm = FcmPush.new("your_api_key", "firebase_project_id")
response = fcm.send(message)
The gem is available as open source under the terms of the MIT License.