Chaos Spawn
==========
[](https://travis-ci.org/meadsteve/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 replacing the ```Kernel.spawn```
functions with overidden ones that return processes that die at random. This should
force an app's supervision tree to actually work.
Currently super alpha. Probably not a good idea to use yet.
## Usage
Add Chaos Spawn as an application in your mix.exs:
```elixir
def application do
[applications: [:logger, :chaos_spawn]]
end
```
### Usage - in manual spawns
Use ```ChaosSpawn.Chaotic.Spawn``` in any module you wish to
have unreliable spawn calls. This will automatically replace the spawn calls
with the versions from the ```ChaosSpawn``` module.
``` elixir
defmodule ChaosSpawn.Example.Spawn do
# Using the following will automatically replace all the spawn
# functions with the chaotic ones.
use ChaosSpawn.Chaotic.Spawn
def test do
spawn fn ->
IO.puts "waiting for message"
receive do
_ -> IO.puts "message recieved!"
end
end
end
end
```
### Usage - in Gen servers
Instead of ```use```ing GenServer ```use``` the chaotic version and then
modify the start_link as below:
```elixir
defmodule ChaosSpawn.Example.GenServer do
use ChaosSpawn.Chaotic.GenServer
def start_link(opts \\ []) do
# This function is imported when using ChaosSpawn.Chaotic.GenServer
start_chaotic_link(__MODULE__, :ok, opts)
# or to switch to the non chaotic version this is imported from GenServer:
# start_link(__MODULE__, :ok, opts)
end
end
```
### Usage - in Gen events
Replace ```GenEvent.start_link``` with ```ChaosSpawn.Chaotic.GenEvent.start_link```.
```elixir
{:ok, pid} = ChaosSpawn.Chaotic.GenEvent.start_link([])
GenEvent.add_handler(pid, SomeHandler, [])
```
### Config
Two keys are provided. The first ```kill_tick``` is the delay in milliseconds
that between chaos spawn checking for processes to kill.
```kill_probability``` is a float between 0 and
1 that determines the probability of a process being killed each tick.
```elixir
config :chaos_spawn, :kill_tick, 1000
config :chaos_spawn, :kill_probability, 0.1
```
## 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/```
