Laravel Prometheus Exporter

A prometheus exporter package for Laravel.

Introduction

Prometheus is a time-series database with a UI and sophisticated querying language (PromQL) that can scrape metrics, counters, gauges and histograms over HTTP.

This package is a wrapper bridging promphp/prometheus_client_php into Laravel.

Installation

Install the package via composer

composer require saschahemleb/laravel-prometheus-exporter

Please see below for instructions on how to enable metrics on Application routes.

Configuration

The package has a default configuration which uses the following environment variables.

PROMETHEUS_NAMESPACE=app

PROMETHEUS_METRICS_ROUTE_ENABLED=true
PROMETHEUS_METRICS_ROUTE_PATH=metrics
PROMETHEUS_COLLECT_FULL_SQL_QUERY=true
PROMETHEUS_STORAGE_ADAPTER=memory

PROMETHEUS_REDIS_CONNECTION=default
PROMETHEUS_REDIS_PREFIX=PROMETHEUS_

To customize the configuration values you can either override the environment variables above (usually this is done in your application's .env file), or you can publish the included prometheus.php to config/prometheus.php.

$ php artisan vendor:publish --provider "Saschahemleb\\LaravelPrometheusExporter\\PrometheusServiceProvider"

Metrics

The package allows you to observe metrics on:

• Application routes. Metrics on request method, request path and status code.
• SQL queries. Metrics on SQL query and query type.

In order to observe metrics in application routes (the time between a request and response), you should register the following middleware in your application's app/Http/Kernel.php:

protected $middleware = [
    \Saschahemleb\LaravelPrometheusExporter\Http\Middleware\ObserveResponseTime::class,
    // [...]
];

The labels exported are

[
    'method',
    'route',
    'status_code',
]

SQL metrics are observed ootb. The labels exported are

[
    'query',
    'query_type',
]

Note: you can disable logging the full query by turning off the configuration of PROMETHEUS_COLLECT_FULL_SQL_QUERY.

Storage Adapters

The storage adapter is used to persist metrics across requests. The memory adapter is enabled by default, meaning data will only be persisted across the current request.

We recommend using the redis or apc adapter in production environments. Of course your installation has to provide a Redis or APC implementation.

The PROMETHEUS_STORAGE_ADAPTER environment variable is used to specify the storage adapter.

Exporting Metrics

The package adds a /metrics endpoint, enabled by default, which exposes all metrics gathered by collectors.

This can be turned on/off using the PROMETHEUS_METRICS_ROUTE_ENABLED environment variable, and can also be changed using the PROMETHEUS_METRICS_ROUTE_PATH environment variable.

Collectors

A collector is a class, implementing the CollectorInterface, which is responsible for collecting data for one or many metrics.

Please see the Example included below.

You can auto-load your collectors by adding them to the collectors array in the prometheus.php config.

Examples

Collector

This is an example collector implementation:

<?php

declare(strict_types = 1);

namespace Saschahemleb\LaravelPrometheusExporter;

use Prometheus\Gauge;use Saschahemleb\LaravelPrometheusExporter\Contracts\CollectorInterface;

class ExampleCollector implements CollectorInterface
{
    /**
     * @var Gauge
     */
    protected $usersRegisteredGauge;

    /**
     * Return the name of the collector.
     *
     * @return string
     */
    public function getName() : string
    {
        return 'users';
    }

    /**
     * Register all metrics associated with the collector.
     *
     * The metrics needs to be registered on the exporter object.
     * eg:
     * ```php
     * $exporter->registerCounter('search_requests_total', 'The total number of search requests.');
     * ```
     *
     * @param PrometheusExporter $exporter
     */
    public function registerMetrics(PrometheusExporter $exporter) : void
    {
        $this->usersRegisteredGauge = $exporter->registerGauge(
            'users_registered_total',
            'The total number of registered users.',
            ['group']
        );
    }

    /**
     * Collect metrics data, if need be, before exporting.
     *
     * As an example, this may be used to perform time consuming database queries and set the value of a counter
     * or gauge.
     */
    public function collect() : void
    {
        // retrieve the total number of staff users registered
        // eg: $totalUsers = Users::where('group', 'staff')->count();
        $this->usersRegisteredGauge->set(36, ['staff']);

        // retrieve the total number of regular users registered
        // eg: $totalUsers = Users::where('group', 'regular')->count();
        $this->usersRegisteredGauge->set(192, ['regular']);
    }
}