# Prometheus.io Plugs Instrumenter/Exporter
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Elixir Plug integration for [prometheus.ex](https://github.com/deadtrickster/prometheus.ex)
Quick introduction by [**@skosch**](https://github.com/skosch): [Monitoring Elixir apps in 2016: Prometheus/Grafana Step-by-Step Guide](http://aldusleaf.org/monitoring-elixir-apps-in-2016-prometheus-and-grafana/)
### Instrumentation
To instrument whole plug pipeline use `Prometheus.PlugPipelineInstrumenter`:
```elixir
defmodule MyApp.Endpoint.PipelineInstrumenter do
use Prometheus.PlugPipelineInstrumenter
end
```
To instrument just a single plug use `Prometheus.PlugInstrumenter`:
```elixir
defmodule MyApp.CoolPlugInstrumenter do
use Prometheus.PlugInstrumenter, [plug: Guardian.Plug.EnsureAuthenticated,
counter: :guardian_ensure_authenticated_total,
histogram: :guardian_ensure_authenticated_duration_microseconds,
labels: [:authenticated]]
end
```
Both modules implement plug interface and `Prometheus.PlugInstrumenter` generates proxy for specified plug so you'll need to replace instrumented plug with your instrumenter in pipeline.
Instrumenters configured via `:prometheus` app environment. Please consult respective modules documentation on
what options are available.
### Exporting
To export metric we first have to create a plug that will serve scraping requests.
```elixir
defmodule MyApp.MetricsExporter do
use Prometheus.PlugExporter
end
```
Then we add exporter to MyApp pipeline:
```elixir
plug MyApp.MetricsExporter
```
You can configure path, export format and Prometheus registry via `:prometheus` app environment.
For more information please see `Prometheus.PlugExporter` module documentation.
Export endpoint can be secured using HTTP Basic Authentication:
```elixir
auth: {:basic, "username", "password"}
```
## Integrations / Collectors / Instrumenters
- [Ecto collector](https://github.com/deadtrickster/prometheus-ecto)
- [Plugs Instrumenter/Exporter](https://github.com/deadtrickster/prometheus-plugs)
- [Elli middleware](https://github.com/elli-lib/elli_prometheus)
- [Fuse plugin](https://github.com/jlouis/fuse#fuse_stats_prometheus)
- [Phoenix instrumenter](https://github.com/deadtrickster/prometheus-phoenix)
- [Process Info Collector](https://github.com/deadtrickster/prometheus_process_collector.erl)
- [RabbitMQ Exporter](https://github.com/deadtrickster/prometheus_rabbitmq_exporter)
## Installation
The package can be installed as:
1. Add prometheus_plug to your list of dependencies in `mix.exs`:
def deps do
[{:prometheus_plugs, "~> 1.0.0"}]
end
2. Ensure prometheus is started before your application:
def application do
[applications: [:prometheus]]
end
## License
MIT