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PlugCheckup

PlugCheckup provides a Plug for adding simple health checks to your app. The JSON output is similar to the one provided by the MiniCheck Ruby library. It was started to provide solarisBank an easy way of monitoring Plug based applications.

Usage

• Add the package to "mix.exs"

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

• Create your checks

defmodule MyHealthChecks do
  def check_db do
    :ok
  end

  def check_redis do
    :ok
  end
end

• Forward your health path to PlugCheckup in your Plug Router

checks = [
  %PlugCheckup.Check{name: "DB", module: MyHealthChecks, function: :check_db},
  %PlugCheckup.Check{name: "Redis", module: MyHealthChecks, function: :check_redis}
]

forward(
  "/health",
  to: PlugCheckup,
  init_opts: PlugCheckup.Options.new(json_encoder: Jason, checks: checks)
)

If you're working with Phoenix, you need to change the syntax slightly to accomodate Phoenix.Router.forward/4:

checks = [
  %PlugCheckup.Check{name: "DB", module: MyHealthChecks, function: :check_db},
  %PlugCheckup.Check{name: "Redis", module: MyHealthChecks, function: :check_redis}
]

forward("/health", PlugCheckup, PlugCheckup.Options.new(json_encoder: Jason, checks: checks))

The Checks

A check is a function with arity zero, which should return either :ok or {:error, term}. In case the check raises an exception or times out, that will be mapped to an {:error, reason} result.

Response

PlugCheckup should return either 200 or 500 statuses, Content-Type header "application/json", and the body should respect this JSON schema

If you configure the error_code option when initializing the plug, the specified value will be used when an error occurs instead of the 500 status.

Demo

Check .iex.exs for a demo of plug_checkup in a Plug.Router. The demo can be run as following.

git clone https://github.com/ggpasqualino/plug_checkup
cd plug_checkup
mix deps.get
iex -S mix

Open your browse either on http://localhost:4000/selfhealth or http://localhost:4000/dependencyhealth