README

This package is a Symfony bundle for exporting metrics to Prometheus. Create your own MetricGenerator services to generate values on-demand, the bundle will expose them under the /metrics endpoint.

It does not provide any metric by default, you have to code your own.

Usage

Require the package

composer require prismamedia/metrics

Register the bundle

# config/bundles.php
return [
    // ...
    PrismaMedia\Metrics\Bundle\PrismaMediaMetricsBundle::class => ['all' => true],
    // ...
];

Import routing file

# config/routes.yaml
metrics:
    resource: '@PrismaMediaMetricsBundle/Resources/config/routes.xml'

Implement your own metric generator

Your metrics are generated on demand by a class implementing PrismaMedia\Metrics\MetricGenerator interface.

The best practice is to create a distinct classes for distinct metric names. Each class can return several values with distinct labels.

In the following example, we expose a metric named app_article_total labelled with each status. In Prometheus (& Grafana), the values can be added in order to get the overall total.

<?php
# src/Metrics/ArticleCountMetric.php

namespace App\Metrics;

use Doctrine\DBAL\Connection;
use PrismaMedia\Metrics\Metric;
use PrismaMedia\Metrics\MetricGenerator;

class ArticleCountMetric implements MetricGenerator
{
    private $connection;
    public function __construct(Connection $connection)
    {
        $this->connection = $connection;
    }

    /**
     * @return Metric[]
     */
    public function getMetrics(): \Traversable
    {
        // SELECT a.status, COUNT(*) as total FROM article GROUP BY a.status
        $qbd = $this->connection->createQueryBuilder();
        $qbd->select('a.status, COUNT(*) as total')
            ->from('article', 'a')
            ->groupBy('a.status');

        foreach ($qbd->execute()->fetchAll() as $row) {
            // app_article_total{status=<status>} <total>
            yield new Metric('app_article_total', (int) $row['total'], [
                'status' => $row['status'],
            ]);
        }
    }
}

Declare the class as a service in you config/services.yaml or config/services.php. It will be automatically tagged prisma_media.metric and added to the aggregator.

The /metrics endpoint will return something like this:

# curl https://localhost:8080/metrics
app_article_total{status=published} 230
app_article_total{status=review} 2
app_article_total{status=draft} 5

Contributing

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.

Please make sure to update tests as appropriate.

License

BSD 3-Clause