shopify / toxiproxy-ruby

A ruby api for Toxiproxy that can be used for resiliency testing.

toxiproxy-ruby

toxiproxy-ruby >= 1.x is compatible with the Toxiproxy 2.x series. toxiproxy-ruby 0.x is compatible with the Toxiproxy 1.x series.

Toxiproxy is a proxy to simulate network and system conditions. The Ruby API aims to make it simple to write tests that ensure your application behaves appropriately under harsh conditions. Before you can use the Ruby library, you need to read the Usage section of the Toxiproxy README.

$ gem install toxiproxy

Make sure the Toxiproxy server is already running.

For more information about Toxiproxy and the available toxics, see the Toxiproxy documentation

Usage

The Ruby client communicates with the Toxiproxy daemon via HTTP. By default it connects to http://127.0.0.1:8474, but you can point to any host:

Toxiproxy.host = 'http://toxiproxy.local:5665'

For example, to simulate 1000ms latency on a database server you can use the latency toxic with the latency argument (see the Toxiproxy project for a list of all toxics):

Toxiproxy[:mysql_master].toxic(:latency, latency: 1000).apply do
  Shop.first # this took at least 1s
end

You can also take an endpoint down for the duration of a block at the TCP level:

Toxiproxy[:mysql_master].down do
  Shop.first # this'll raise
end

If you want to simulate all your Redis instances being down:

Toxiproxy[/redis/].down do
  # any redis call will fail
end

If you want to simulate that your cache server is slow at incoming network (upstream), but fast at outgoing (downstream), you can apply a toxic to just the upstream:

Toxiproxy[:cache].upstream(:latency, latency: 1000).apply do
  Cache.get(:omg) # will take at least a second
end

By default the toxic is applied to the downstream connection, you can be explicit and chain them:

Toxiproxy[/redis/].upstream(:slow_close, delay: 100).downstream(:latency, jitter: 300).apply do
  # all redises are now slow at responding and closing
end

See the Toxiproxy README for a list of toxics.

Populate

To populate Toxiproxy pass the proxy configurations to Toxiproxy#populate:

Toxiproxy.populate([{
  name: "mysql_master",
  listen: "localhost:21212",
  upstream: "localhost:3306",
},{
  name: "mysql_read_only",
  listen: "localhost:21213",
  upstream: "localhost:3306",
}])

This will create the proxies passed, or replace the proxies if they already exist in Toxiproxy. It's recommended to do this early as early in boot as possible, see the Toxiproxy README. If you have many proxies, we recommend storing the Toxiproxy configs in a configuration file and deserializing it into Toxiproxy.populate.

If you're doing this in Rails, you may have to do this in config/boot.rb (as early in boot as possible) as older versions of ActiveRecord establish a database connection as soon as it's loaded.