Chaos Spawn

What and why

Inspired by netfix's chaos monkey. This library is intended to be a low level process based equivalent. It works by storing a list of procceses that are periodically terminated at random. Helper modules are provided to make it easy to register proceses as ones that can be killed. The intention is that this should force the design of an app's supervision tree to actually work.

This is still fairly early alpha work. So please test before adding to any live projects you may have.

Installation

Add the following to your mix.exs dependencies:

defp deps do
  [ {:chaos_spawn, "~> 0.3.0"} ]
end

then add chaos_spawn as an application in your mix.exs:

def application do
  [applications: [:logger, :chaos_spawn]]
end

Usage

Control

The moment the app is started chaos spawn starts potential killing processes. This can be stopped by calling

  ChaosSpawn.stop

and then later restarted with:

  ChaosSpawn.start

Registering processes to kill

By default no processes are eligible to be killed by chaos spawn. The following documents show how to do this:

HOWTO: Add chaos spawn using the provided helper modules

HOWTO: Add chaos spawn manually

Example

An example of using this with the phoenix web framework can be found here: https://github.com/meadsteve/chaos-spawn-example

Config

A number of options are provided:

kill_tick

The delay in milliseconds between chaos spawn checking for processes to kill.

kill_probability

A float between 0 and 1 that determines the probability of a process being killed each tick.

only_kill_between

Takes a start and end time (always utc) and chaos spawn will only kill processes between these times.

config :chaos_spawn, :kill_tick, 1000
config :chaos_spawn, :kill_probability, 0.1
config :chaos_spawn, :only_kill_between, {{10, 00, 00}, {16, 00, 00}}

Contributing

Contributions to this repo are more than welcome. Guidlines for succesfull PRs:

• Any large changes should ideally be opened as an issue first so a disucssion can be had.
• Code should be tested.
• Code under lib/ should conform to coding standards tested by https://github.com/lpil/dogma . You can test this by running mix dogma lib/