Eventboss

AWS based Pub/Sub implementation in Ruby.

Features

• [x] language agnostic (ruby, js http://github.com/AirHelp/eventboss-js)
• [x] fluent interface
• [x] multithread polling (multi polling strategy)
• [x] generic queues (multiple apps sending the same event)
• [x] postponing jobs
• [x] automatic serialization/deserialization
• [x] batch sending (SQS one-to-one)
• [x] support multiple environments in the same AWS account
• [x] pluggable error handlers (airbrake, newrelic)
• [x] utility tasks (deadletter reload)
• [x] localstack compatible
• [x] rails support (preloads rails environment)
• [x] development mode (creates missing SNS/SQS on the fly)
• [ ] terraform pub/sub scripts
• [ ] alternative infrastructure (redis?, kafka?)
• [ ] message compression
• [ ] alternative serialization (protobuf)
• [ ] subscription filtering
• [ ] fifo queues support

Installation

Add this line to your application's Gemfile:

gem 'eventboss'

Usage

Run the listener by:

bundle exec eventboss

it will read conf values from ENV variables in configuration sections.

Broadcasting events:

publisher = Eventboss.publisher(event_name)
publisher.publish(payload)

Unicasting events in batches: (via SQS)

sender = Eventboss.sender(event_name, destination_app)
sender.send_batch([payload1, payload2])

Receiving events via listeners:

class AnyName
  include Eventboss::Listener
  eventboss_options source_app: 'src_app_name', event_name: 'my_event'

  def receive(payload)
  end
end

Configuration

By default, no exception will be raised when publisher configuration is missing (eventboss_region, eventboss_account_id, eventboss_app_name). This can lead to false-positive specs, app not working without exceptions on dev/stg/prod environment. It's strongly advised to set raise_on_missing_configuration to true.

Using .configure:

Eventboss.configure do |config|
  config.raise_on_missing_configuration = true
  config.eventboss_account_id = 1234567
  config.eventboss_app_name = name
  config.eventboss_region = aws_region
  config.concurrency = 10
  # when using custom clients like localstack
  config.sns_client = client # Custom SNS Client can be used, i.e. to use local mock, see: https://github.com/phstc/shoryuken/wiki/Using-a-local-mock-SQS-server
  config.logger = MyLogger.new
  config.sqs_client = Aws::SQS::Client.new(endpoint: 'http://localstack:4576', region: 'us-east-1', credentials: Aws::Credentials.new('fake', 'fake'))
end

Using ENVs:

EVENTBOSS_ACCOUNT_ID=12345676
EVENTBOSS_APP_NAME=application_name
EVENTBOSS_ENV=env_name # production/staging/test
EVENTBOSS_REGION=aws_region # i.e. eu-west-1
EVENTBOSS_CONCURRENCY=10 # default is 25

AWS_SNS_ENDPOINT=http://localhost:4566 # when using with localstack
AWS_SQS_ENDPOINT=http://localhost:4566 # when using with localstack

Use fixed account ID for localstack setup:

EVENTBUS_ACCOUNT_ID=000000000000

Be aware that eventbus:deadletter:reload rake task won't load your configuration if you are not using ENVs in non Rails app, although to make it work you can extend your Rakefile with:

load File.join(Gem::Specification.find_by_name('eventboss').gem_dir, 'lib', 'tasks', 'eventboss.rake')

task :environment do
  # Load your environment
  # Example:
  # require_relative 'config/application'
end

task 'eventboss:deadletter:reload': :environment

Using eventboss.yml:

concurrency: 10
listeners:
  # It doesn't make much sense to use both include and exclude.
  include:
    - MyListener # It will run only listed listeners (MyListener). If MyListener was listed in exclude it would be omitted as well.
  exclude:
    - OtherListener # When include option is not set it will run all listeners except listed here (OtherListener). When include is set it will run only included (but not excluded) listeners.

YAML config is optional and by default is loaded from './config/eventboss.yml'. You can also pass config path as an argument:

eventboss -C my/custom/path/to/config.yml

YAML config content is merged to configuration last, which means it overwrites ENVs and .configure.

Logging and error handling

To have more verbose logging, set log_level in configuration (default is info).

Logger is used as default error handler. There is Airbrake handler available, to use it ensure you have airbrake or airbrake-ruby gem and add it to error handlers stack:

Eventboss.configure do |config|
  config.error_handlers << Eventboss::ErrorHandlers::Airbrake.new
end

Middlewares

Server middlewares intercept the execution of your Listeners. You can use to extract and run common functions on every message received.

Define a middleware in the following way:

class LogMiddleware < Eventboss::Middleware::Base
  def call(_work)
    yield
    logger.debug 'finished with success'
  rescue StandardError => _error
    logger.error 'finished with error'
    raise
  end

  private

  def logger
    @logger ||= @options.fetch(:logger)
  end
end

And configure your logger as such:

Eventboss.configure do |config|
  config.server_middleware.add LogMiddleware, logger: Logger.new
end

Development mode

In the development mode you don't need to create the infrastructure required by the application - Eventboss will take care of this.

It works on AWS and localstack.

Following resources are created:

• SNS topics - created when application starts and when message is published
• SQS queues (with SendMessage policy) - created when application starts
• subscriptions for topics and queues - created when application starts

Just enable it via environment variable...

EVENTBOSS_DEVELOPMENT_MODE=true

use fixed account ID for localstack setup...

EVENTBUS_ACCOUNT_ID=000000000000 # or set it via YAML

...and you're good to go: ```shell script bundle exec eventboss

## Topics & Queues naming convention

The SNSes should be named in the following pattern:

eventboss-src_app_name-event_name-environment

i.e.

eventboss-srcapp-transaction_change-staging

The corresponding SQSes should be named like:

dest_app_name-eventboss-src_app_name-event_name-environment dest_app_name-eventboss-src_app_name-event_name-environment-deadletter

i.e.

destapp-eventboss-srcapp-transaction_change-staging destapp-eventboss-srcapp-transaction_change-staging-deadletter

## Contributing

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


## License

The gem is available as open source under the terms of the [MIT License](http://opensource.org/licenses/MIT).