Sc4ry provide the Circuit Breaker Design Pattern for your applications
Simple CircuitBreacker 4 RubY
Add this line to your application's Gemfile:
gem 'sc4ry'And then execute:
$ bundle install
Or install it yourself as:
$ gem install sc4ry
A quick circuit test : create a test script lile test.rb :
require 'rubygems'
require 'sc4ry'
include Sc4ry
Circuits.register circuit: :mycircuit, config: {:notifiers => [:prometheus,:mattermost],
:exceptions => [Errno::ECONNREFUSED, URI::InvalidURIError]}
Circuits.run do # circuit: :mycircuit is optional, run work with the first circuit registered
puts RestClient.get('http://your_service/endpoint')
end
Default values, circuit is half open before one of the max count is reached :
- :max_failure_count
description : maximum failure before opening circuit
default value : 5
- :timeout_value
description : timeout value, if :timeout => true
default value : 20
- :timeout
description : (de)activate internal timeout
default value : false
- :max_timeout_count
description : maximum timeout try before opening circuit
default value* : 5
- :max_time
description : maximum time for a circuit run
default value : 10
- :max_overtime_count
description : maximum count of overtime before opening circuit
default value : 3
- :check_delay
description : delay after opening, before trying again to closed circuit or after an other check
default value : 30
- :notifiers
description : active notifier, must be :symbol in [:prometheus, :mattermost]
default value : []
- :forward_unknown_exceptions
description : (de)activate forwarding of unknown exceptions, just log in DEBUG if false
default value : true
- :raise_on_opening
description : (de)activate raise specific Sc4ry exceptions ( CircuitBreaked ) if circuit opening
default value : false
- :exceptions
description : [StandardError, RuntimeError]
default value : list of selected Exceptions considered for failure, others are SKIPPED.
This script could be usefull to test all feature on your installation
You need:
- Redis
- Prometheus pushgateway
- an endpoint if you want to check real endpoint
- a Mattermost/Slack incoming webhook (optional)
You could gate all this pre-requistes simply if you jave docker up on your machine
$ docker pull redis:latest
$ docker run --rm -d -p 6379:6379/tcp redis:latest
$ docker pull prom/pushgateway:latest
$ docker run --rm -d -p 9091:9091 prom/pushgateway:latest
$ git clone https://github.com/Ultragreen/MockWS.git
$ cd MockWS
$ rackup
create the test script like :
require 'rubygems'
require 'sc4ry'
include Sc4ry
# display of default Sc4ry config
puts '1.1/ CONFIG : Initial default config'
Circuits.default_config.each do |item,value|
puts " * #{item} : #{value}"
end
puts ''
# testing the two ways to configure Sc4ry default config
puts "1.2/ CONFIG : modifying default config activate timout and set max_time to 12"
Circuits.merge_default_config diff: {timeout: true }
Circuits.configure do |spec|
spec.max_time = 12
end
puts ''
# display default config, must be override with a nested hash by calling default_config= method
puts '1.3/ CONFIG : Default config updated:'
Circuits.default_config.each do |item,value|
puts " * #{item} : #{value}"
end
puts ''
# display current data Store
print "2.1/ STORE : Current datastore backend : "
puts Circuits.store.current
puts ''
# display available backend
puts "2.2/ STORE : List of existing backends : "
Circuits.store.list_backend.each do |backend|
puts " - #{backend}"
end
puts ''
# display Redis backend config in store before change
puts '2.3/ STORE : display default config of redis backend'
Circuits.store.get_config(backend: :redis).each do |item,value|
puts " * #{item} : #{value}"
end
puts ''
# reconfigure a backend
puts "2.4/ STORE : reconfigure Redis backend"
Circuits.store.config_backend name: :redis, config: {:host => 'localhost', :port => 6379, :db => 10 }
puts
# display after
puts '2.5/ STORE : display altered config of redis backend'
Circuits.store.get_config(backend: :redis).each do |item,value|
puts " * #{item} : #{value}"
end
puts ''
# change backend
puts '2.6/ STORE : change to redis backend (NEED a Redis installed) '
puts " $ docker pull redis:latest"
puts " $ docker run --rm -d -p 6379:6379/tcp redis:latest"
Circuits.store.change_backend name: :redis
puts ''
puts '2.7/ STORE : flush redis backend, just for test, and for idempotency (NEED a Redis installed) '
Circuits.store.flush
puts ''
# defining a circuit, config must be empty or override from default
puts "3.1/ CIRCUIT : registering a circuit by merge :"
Circuits.register circuit: :test, config: {:notifiers => [:prometheus,:mattermost], :exceptions => [Errno::ECONNREFUSED, URI::InvalidURIError] }
puts ""
puts "3.2/ CIRCUIT : registering a circuit by block :"
Circuits.register circuit: :test2 do |spec|
spec.exceptions = [Errno::ECONNREFUSED]
end
puts ''
puts "3.3/ CIRCUIT : registering a circuit by default :"
Circuits.register circuit: :test3
puts ''
puts "3.4/ CIRCUITS : Circuits list"
Circuits::list.each do |circuit|
puts " * #{circuit}"
end
puts ""
puts "3.5/ CIRCUIT : display a circuit config :test3 :"
Circuits.get(circuit: :test3).each do |item,value|
puts " * #{item} : #{value}"
end
puts ""
puts "3.6/ CIRCUIT : update config of :test3 => :raise_on_opening == true :"
Circuits.update_config circuit: :test3, config: {raise_on_opening: true}
puts ''
puts "3.7/ CIRCUIT : display a circuit config :test3 after change :"
Circuits.get(circuit: :test3).each do |item,value|
puts " * #{item} : #{value}"
end
puts ""
puts "3.8/ unregister a circuit : :test2 :"
Circuits.unregister circuit: :test2
puts ''
puts "3.9/ CIRCUITS : Circuits list after unregister"
Circuits::list.each do |circuit|
puts " * #{circuit}"
end
puts ""
# Config an alternate logger
puts "4.1/ LOGGER : register a logger on file "
Circuits.loggers.register name: :perso, instance: ::Logger.new('/tmp/logfile.log')
puts ''
puts "4.2/ LOGGER : get the list of available loggers"
Circuits.loggers.list_available.each do |logger|
puts " * #{logger}"
end
puts ''
puts "4.3/ LOGGER : change logger to :perso"
Circuits.loggers.current = :perso
puts ""
# sample Mattermost notification
puts "5/ set notifier mattermost on dummy url, change with your slack or mattermost server"
Sc4ry::Notifiers::config name: :mattermost, config: {:url => 'https://mattermost.mycorp.com', :token => "<TOKEN>"}
puts ""
# sample loop
puts "6/ running circuits test, please wait ... (see /tmp/logfile.log for result)"
puts " check endoint status for different result, you cloud use http://github.com/Ultragreen/MockWS for testing endpoint, on an other tty"
puts " $ git clone https://github.com/Ultragreen/MockWS.git"
puts " $ cd MockWS"
puts " $ rackup"
begin
10.times do
sleep 1
Circuits.run circuit: :test do
# for the test choose or build an endpoint you must shutdown
puts RestClient.get('http://localhost:9292/test2/data')
end
end
rescue Interrupt
puts 'Interrputed'
ensure
Circuits.store.flush
end
puts "end"After checking out the repo, run bin/setup to install dependencies. Then, run rake spec 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/Ultragreen/sc4ry.
The gem is available as open source under the terms of the MIT License.