edditor/prometheus-metrics-bundle

Symfony 5/6 Prometheus Metrics Bundle

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Symfony 5 and 6 Prometheus Metrics Bundle

A Symfony bundle for the promphp/prometheus_client_php.

Installation

Applications that use Symfony Flex

Open a command console, enter your project directory and execute:

$ composer require artprima/prometheus-metrics-bundle

Applications that don't use Symfony Flex

Step 1: Download the Bundle

Open a command console, enter your project directory and execute the following command to download the latest stable version of this bundle:

$ composer require artprima/prometheus-metrics-bundle

This command requires you to have Composer installed globally, as explained in the installation chapter of the Composer documentation.

Step 2: Enable the Bundle

Then, enable the bundle by adding it to the list of registered bundles in the app/AppKernel.php file of your project:

<?php
// app/AppKernel.php

// ...
class AppKernel extends Kernel
{
    public function registerBundles()
    {
        $bundles = [
            // ...
            new Artprima\PrometheusMetricsBundle\ArtprimaPrometheusMetricsBundle(),
        ];

        // ...
    }

    // ...
}

Configuration

config.yaml

artprima_prometheus_metrics:
    # namespace is used to prefix the prometheus metrics
    namespace: myapp

    # ignoring some routes in metrics
    ignored_routes: [some_route_name, another_route_name]

    # metrics backend
    storage:
        # DSN of the storage. All parsed values will override explicitly set parameters. Ex: redis://127.0.0.1?timeout=0.1
        url: ~
        
        # Known values: in_memory, apcu, apcng, redis
        type: in_memory
        
        # Available parameters used by redis
        host: 127.0.0.1
        port: 6379
        timeout: 0.1
        read_timeout: 10
        persistent_connections: false
        password: ~
        database: ~ # Int value used by redis adapter
        prefix: ~   # String value used by redis and apcu

        # A variable parameter to define additionnal options as key / value.
        options:
            foo: bar

    # used to disable default application metrics
    disable_default_metrics: false

    # used to disable default metrics from promphp/prometheus_client_php
    disable_default_promphp_metrics: false

    # used to enable console metrics
    enable_console_metrics: false

Supported types are:

Adapter name	Prometheus class
in_memory	Prometheus\Storage\InMemory
apcu	Prometheus\Storage\APC
apcng	Prometheus\Storage\APCng
redis	Prometheus\Storage\Redis

routes.yaml

# expose /metrics/prometheus in your application
app_metrics:
    resource: '@ArtprimaPrometheusMetricsBundle/Resources/config/routing.xml'

You can alternatively define your own path and rules:

app_metrics:
    path: /mypath/mymetrics
    controller: Artprima\PrometheusMetricsBundle\Controller\MetricsController::prometheus

Now your metrics are available to Prometheus using http://<yourapp_url>/metrics/prometheus.

Custom Metrics Collector

If you want to collect your own metrics, you should create a class that will implement one or several interfaces that are the children of the Artprima\PrometheusMetricsBundle\Metrics\MetricsCollectorInterface.

<?php

declare(strict_types=1);

namespace App\Metrics;

use Artprima\PrometheusMetricsBundle\Metrics\RequestMetricsCollectorInterface;
use Artprima\PrometheusMetricsBundle\Metrics\TerminateMetricsCollectorInterface;
use Prometheus\CollectorRegistry;
use Symfony\Component\HttpKernel\Event\RequestEvent;
use Symfony\Component\HttpKernel\Event\TerminateEvent;

/**
 * Class MyMetricsCollector.
 */
class MyMetricsCollector implements RequestMetricsCollectorInterface, TerminateMetricsCollectorInterface
{
    /**
     * @var string
     */
    private $namespace;

    /**
     * @var CollectorRegistry
     */
    private $collectionRegistry;

    public function init(string $namespace, CollectorRegistry $collectionRegistry): void
    {
        $this->namespace = $namespace;
        $this->collectionRegistry = $collectionRegistry;
    }

    private function incRequestsTotal(?string $method = null, ?string $route = null): void
    {
        $counter = $this->collectionRegistry->getOrRegisterCounter(
            $this->namespace,
            'http_requests_total',
            'total request count',
            ['action']
        );

        $counter->inc(['all']);

        if (null !== $method && null !== $route) {
            $counter->inc([sprintf('%s-%s', $method, $route)]);
        }
    }

    private function incResponsesTotal(?string $method = null, ?string $route = null): void
    {
        $counter = $this->collectionRegistry->getOrRegisterCounter(
            $this->namespace,
            'http_responses_total',
            'total response count',
            ['action']
        );
        $counter->inc(['all']);

        if (null !== $method && null !== $route) {
            $counter->inc([sprintf('%s-%s', $method, $route)]);
        }
    }

    // called on the `kernel.request` event
    public function collectRequest(RequestEvent $event): void
    {
        $request = $event->getRequest();
        $requestMethod = $request->getMethod();
        $requestRoute = $request->attributes->get('_route');

        // do not track "OPTIONS" requests
        if ('OPTIONS' === $requestMethod) {
            return;
        }

        $this->incRequestsTotal($requestMethod, $requestRoute);
    }

    // called on the `kernel.terminate` event
    public function collectResponse(TerminateEvent $event): void
    {
        $response = $event->getResponse();
        $request = $event->getRequest();

        $requestMethod = $request->getMethod();
        $requestRoute = $request->attributes->get('_route');

        $this->incResponsesTotal($requestMethod, $requestRoute);
    }
}

When using autoconfigure = true, by implementing Artprima\PrometheusMetricsBundle\Metrics\MetricsCollectorInterface Symfony will automatically configure your metrics collector to be used by the collector registry.

By implementing one of the following interfaces you can collect the metrics on one of the listed Symfony kernel events:

• Artprima\PrometheusMetricsBundle\Metrics\PreRequestMetricsCollectorInterface
  • collect metrics on "kernel.request" event with a priority of 1024.
• Artprima\PrometheusMetricsBundle\Metrics\RequestMetricsCollectorInterface
  • collect metrics on "kernel.request" event (default priority).
• Artprima\PrometheusMetricsBundle\Metrics\PreExceptionMetricsCollectorInterface
  • collect metrics on "kernel.exception" event with a priority of 1024.
• Artprima\PrometheusMetricsBundle\Metrics\ExceptionMetricsCollectorInterface
  • collect metrics on "kernel.exception" event with (default priority).
• Artprima\PrometheusMetricsBundle\Metrics\TerminateMetricsCollectorInterface
  • collect metrics on "kernel.terminate" event.

The following collectors will only work if you define enable_console_metrics: true in the bundle configuration:

• Artprima\PrometheusMetricsBundle\Metrics\ConsoleCommandMetricsCollectorInterface
  • collect metrics on "console.command" event.
• Artprima\PrometheusMetricsBundle\Metrics\ConsoleTerminateMetricsCollectorInterface
  • collect metrics on "console.terminate" event.
• Artprima\PrometheusMetricsBundle\Metrics\ConsoleErrorMetricsCollectorInterface
  • collect metrics on "console.error" event.

For advanced usage you can implement Artprima\PrometheusMetricsBundle\Metrics\MetricsCollectorInterface directly.

There is also Artprima\PrometheusMetricsBundle\Metrics\MetricsCollectorInitTrait will add the init method to your collector.

If you don't use autoconfigure = true, then you will have to add this to your services.yaml:

    App\Metrics\MyMetricsCollector:
        tags:
            - { name: prometheus_metrics_bundle.metrics_generator }

Custom Storage Adapter Factory

A storage adapter is an instance of Prometheus\Storage\Adapter. To create your own storage adapter you should create a custom factory implementing Artprima\PrometheusMetricsBundle\StorageFactory\StorageFactoryInterface.

<?php

declare(strict_types=1);

namespace App\Metrics;

use Artprima\PrometheusMetricsBundle\StorageFactory\StorageFactoryInterface;
use Prometheus\Storage\Adapter;

class DummyFactory implements StorageFactoryInterface
{
    public function getName(): string
    {
        return 'dummy';
    }

    public function create(array $options): Adapter
    {
        return new Dummy($options);
    }
}

Symfony will automatically configure your storage factory with autoconfigure = true and implementing Artprima\PrometheusMetricsBundle\StorageFactory\StorageFactoryInterface. If you don't use autoconfigure = true, then you will have to add this to your services.yaml:

    App\Metrics\DummyFactory:
        tags:
            - { name: prometheus_metrics_bundle.adapter_factory }

Default Metrics

These are default metrics exported by the application:

# TYPE php_info gauge
php_info{version="7.3.25-1+ubuntu18.04.1+deb.sury.org+1"} 1
# HELP symfony_http_2xx_responses_total total 2xx response count
# TYPE symfony_http_2xx_responses_total counter
symfony_http_2xx_responses_total{action="GET-app_dummy_homepage"} 1
symfony_http_2xx_responses_total{action="all"} 1
# HELP symfony_http_requests_total total request count
# TYPE symfony_http_requests_total counter
symfony_http_requests_total{action="GET-app_dummy_homepage"} 1
symfony_http_requests_total{action="all"} 1
# HELP symfony_instance_name app instance name
# TYPE symfony_instance_name gauge
symfony_instance_name{instance="dev"} 1

Note that, php_info comes from the underlying library promphp/prometheus_client_php. Other metrics are gathered by the built-in class Artprima\PrometheusMetricsBundle\Metrics. Here, in the example we have a prefix symfony and the metrics show a single request to the root named app_dummy_homepage. Symfony instance is named dev here. Instance name comes from the server var HOSTNAME ($request->server->get('HOSTNAME')) and defaults to dev.

Clear Metrics

The bundle provides a console command to clear metrics from the storage. Simply run:

./bin/console artprima:prometheus:metrics:clear

Code license

You are free to use the code in this repository under the terms of the MIT license. LICENSE contains a copy of this license.