bundle add hanami-events-cloud_pubsub

# config/environment.rb
# ...
require_relative './../lib/my_app'
require_relative './../apps/web/application'
# ...

require 'hanami/events/cloud_pubsub/register' # <----

# config/environment.rb

Hanami.configure do
  environment :development do
    cloud_pubsub do |config|
      config.pubsub = { project_id: 'emulator' } # optional
      config.logger = Hanami.logger # optional
      config.namespace = :staging # optional
      config.auto_create_topics = false # optional
      config.auto_create_subscriptions = false # optional
      config.on_shutdown = ->(adapter) { Analytics.flush } # optional
      config.error_handlers << ->(err, message) { MyErrorReporter.report(err) }
      # ...
    end
  end
end

Hanami.events.subscribe('user.deleted', id: 'my-subscriber-id') do |payload|
  puts "Deleted user: #{payload}"
end

Hanami.events.subscribe('foo', id: 'bar', deadline: 30) do |payload|
  sleep 29 # message will finish before deadline
end

# config/cloudpubsub.rb

require 'config/environment'

Hanami.boot

class CustomMiddleware
  def call(message)
    puts 'Middleware started!'
    yield
    puts 'Middleware ended!'
  end
end

Hanami::Events::CloudPubsub.configure do |config|
  # required
  config.subscriptions_loader = -> do
    # Ensure these files are not loaded until *after* the subscriptions are
    # setup, or else you will have an undefined reference to `$events`
    Hanami::Utils.require! 'apps/web/subscriptions'
  end

  # (optional)
  config.logger = Hanami.logger

  # (optional)
  config.error_handlers << lambda do |err, message|
    Honeybadger.notify(err, context: message.attributes)
  end

  config.middleware << CustomMiddleware.new # must respond to #call
end

require 'hanami/events/cloud_pubsub/middleware/request_id'

Hanami::Events::CloudPubsub.configure do |config|
  # ...
end