Gcpc

Google Cloud Pub/Sub Client for Ruby.

Gcpc provides the implementation of the publisher / subscriber for Google Cloud Pub/Sub. You can add some functionality to the publisher / subscriber as interceptors.

Add this line to your application's Gemfile:

gem 'gcpc'

And then execute:

$ bundle

Or install it yourself as:

$ gem install gcpc

gcpc have publisher and subscriber implementation of Google Cloud Pub/Sub.

To use Gcpc::Publisher, pleaese initialize Gcpc::Publisher with some configurations.

publisher = Gcpc::Publisher.new(
  project_id:  "<project id>",
  topic:       "<topic name>",
  credentials: "/path/to/credentials",
)

Then, simply call Gcpc::Publisher#publish to post a message!

publisher.publish("<message payload>")

By using interceptors, you can add some functionality to the publisher.

For example, you can add logging functionality by adding LogInterceptor as shown below.

class LogInterceptor < Gcpc::Publisher::BaseInterceptor
  MyLogger = Logger.new(STDOUT)

  # @param [String] data
  # @param [Hash] attributes
  def publish(data, attributes)
    MyLogger.info "[Interceptor Log] publish data: \"#{data}\", attributes: #{attributes}"
    yield data, attributes
  end
end

publisher = Gcpc::Publisher.new(
  project_id:   "<project id>",
  topic:        "<topic name>",
  interceptors: [LogInterceptor],
  credentials:  "/path/to/credentials",
)

publisher.publish("<message payload>")

A full example code is in publisher-example. Please see it.

To use Gcpc::Subscriber, pleaese initialize Gcpc::Subscriber with some configurations.

subscriber = Gcpc::Subscriber.new(
  project_id:   "<project id>",
  subscription: "<subscription name>",
  credentials:  "/path/to/credentials",
)

Then, call Gcpc::Subscriber#handle to register a handler. A registered handler executes #handle callback for each published message.

class NopHandler < Gcpc::Subscriber::BaseHandler
  # @param [String] data
  # @param [Hash] attributes
  # @param [Google::Cloud::Pubsub::ReceivedMessage] message
  def handle(data, attributes, message)
    # Do nothing. Consume only.
  end
end

subscriber.handle(NopHandler)

To start subscribing, please call Gcpc::Subscriber#start. It does not return, and run subscribing loops in it.

subscriber.run

By default, you can stop a subscriber process by sending SIGINT, SIGTERM, or SIGKILL signals.

If you want to use other signals, please pass signals to #run.

subscriber.run(['SIGINT', 'SIGTERM', 'SIGSTOP', 'SIGTSTP'])

By using interceptors, you can add some functionality to the subscriber.

For example, you can add logging functionality by adding LogInterceptor as shown below.

class LogInterceptor < Gcpc::Subscriber::BaseInterceptor
  MyLogger = Logger.new(STDOUT)

  # @param [String] data
  # @param [Hash] attributes
  # @param [Google::Cloud::Pubsub::ReceivedMessage] message
  def handle(data, attributes, message)
    MyLogger.info "[Interceptor Log] subscribed a message: #{message}"
    yield data, attributes, message
  end
end

subscriber = Gcpc::Subscriber.new(
  project_id:   "<project id>",
  subscription: "<subscription name>",
  interceptors: [LogInterceptor],
  credentials:  "/path/to/credentials",
)

A full example code is in subscriber-example. Please see it.

After checking out the repo, run bin/setup to install dependencies. Then, run bundle exec rspec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/wantedly/gcpc.

The gem is available as open source under the terms of the MIT License.