View Source Existence
Asynchronous dependency health checks library.
Features
- User defined dependencies checks with flexible settings.
- Dependencies checks functions are executed asynchronously.
- Built-in
Plug
module providing customizable response for a http health-check endpoint. - Support for multiple independent
Existence
instances and associated health-checks endpoints (example use case: separate Kubernetes readiness and liveness http probes). - Checks states are stored and accessed using a dedicated ETS tables per
Existence
instance, which means practically unlimited requests per second processing capacity.
Installation
Add Existence
library to your application dependencies:
def deps do
[
{:existence, github: "recruitee/existence", branch: "master"}
]
end
Usage
Define dependencies checks functions MFA's and start Existence
child with your application
supervisor
defmodule MyApp.Application do
use Application
def start(_type, _args) do
health_checks = [
check_1: %{mfa: {MyApp.Checks, :check_1, []}},
check_2: %{mfa: {MyApp.Checks, :check_2, []}}
]
children = [{Existence, checks: health_checks}]
opts = [strategy: :one_for_one, name: MyApp.Supervisor]
Supervisor.start_link(children, opts)
end
end
Declare your dependencies checks functions:
defmodule MyApp.Checks do
def check_1(), do: :ok
def check_2(), do: :ok
end
Configure your Phoenix router to respond to the /healthcheck
endpoint requests using for example
Plug.Router.forward/2
:
defmodule MyAppWeb.Router do
use MyAppWeb, :router
forward("/healthcheck", Existence.Plug)
end
Get current overall health-check state:
iex> Existence.get_state()
:ok
List individual dependencies checks current states:
iex> Existence.get_checks()
[check_1: :ok, check_2: :ok]
TODO
- [ ] add
telemetry
event emitted on an overall health-check state change.