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# PlugCheckup
PlugCheckup provides a Plug for adding simple health checks to your app. The [JSON output](#response) is similar to the one provided by the [MiniCheck](https://github.com/workshare/mini-check) Ruby library. It was started at [solarisBank](https://www.solarisbank.de/en/) as an easy way of providing monitoring to our Plug based applications.
## Usage
- Add the package to "mix.exs"
```elixir
defp deps do
[
{:plug_checkup, "~> 0.2.0"}
]
end
```
- Create your [checks](#the-checks)
```elixir
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
```elixir
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{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 the following JSON schema
```json
{
"$schema": "http://json-schema.org/draft-06/schema#",
"title": "Health check list",
"type": "array",
"items": {
"title": "Check",
"type": "object",
"properties": {
"name": {
"description": "The name of this check, for example: 'redis', or 'postgres'",
"type": "string"
},
"healthy": {
"description": "If the check was successful or not",
"type" : "boolean"
},
"time": {
"description": "How long the check took to run",
"type": "integer"
},
"error": {
"description": "The error reason in case the check fails",
"type": "string"
}
}
}
}
```
