Prometheus Messenger Middleware

A Simple Middleware to Monitor your Symfony Messenger Component with two Prometheus Counter Metrics per MessageBus.

• Counter overall executed Messages
• Counter failed Messages

Dependencies

• PHP >= 7.2.5
• promphp/prometheus_client_php
• symfony/messenger

Installation

composer require fjogeleit/prometheus-messenger-middleware

Usage

Configure this Middleware to your MessageBus

Symfony Basic Example

Register your Services

services:
    Prometheus\Storage\InMemory: ~
    Prometheus\CollectorRegistry: ['@Prometheus\Storage\InMemory']

    PrometheusMiddleware\PrometheusMiddleware: ~

Configure Middleware

framework:
    messenger:
        buses:
            message.bus.commands:
                middleware:
                    - 'PrometheusMiddleware\PrometheusMiddleware'

Generated Example Counter Response with the default Labels "message" as full qualified MessageName and "label" as Message ClassName

# HELP message_bus_commands_messenger Executed Messages
# TYPE message_bus_commands_messenger counter
message_bus_commands_messenger{message="PrometheusMiddleware\\\\Tests\\\\Example\\\\FooMessage",label="FooMessage"} 2
message_bus_commands_messenger{message="PrometheusMiddleware\\\\Tests\\\\Example\\\\FooMessage",label="BarMessage"} 1

Advanced Usage

You can also configure your own Labels and provide the related Values

Configure your own labels as additional service argument

services:
    ...

    PrometheusMiddleware\PrometheusMiddleware:
      arguments:
        $labels: ['message', 'label','value']
        

Create a LabelValueProvider

Create your own LabelValueProvider by implementing the LabelValueProviderInterface

<?php

declare(strict_types=1);

namespace PrometheusMiddleware\Tests\Example\LabelValueProvider;

use PrometheusMiddleware\LabelValueProviderInterface;
use PrometheusMiddleware\Tests\Example\FooMessage;
use Symfony\Component\Messenger\Envelope;
use Symfony\Component\Messenger\Middleware\StackInterface;

class FooLabelValueProvider implements LabelValueProviderInterface
{
    public function __invoke(Envelope $envelope, StackInterface $stack): array
    {
        /** @var FooMessage $message */
        $message = $envelope->getMessage();

        return [
            \get_class($message),
            substr(strrchr(get_class($message), '\\'), 1),
            $message->getBar()
        ];
    }
}

Add your new LabelValueProvider to your ServiceConfiguration

services:
    ...
    PrometheusMiddleware\Tests\Example\FooLabelValueProvider: ~

    PrometheusMiddleware\PrometheusMiddleware:
      arguments:
        $labels: ['message', 'label','value']
        $labelValueProvider: '@PrometheusMiddleware\Tests\Example\FooLabelValueProvider'

You can also provide custom labels for the ErrorCounter with the ErrorLabelValueProviderInterface

<?php

declare(strict_types=1);

namespace PrometheusMiddleware\Tests\Example\LabelValueProvider;

use PrometheusMiddleware\ErrorLabelValueProviderInterface;
use PrometheusMiddleware\Tests\Example\FooMessage;
use Symfony\Component\Messenger\Envelope;
use Symfony\Component\Messenger\Middleware\StackInterface;

class FooExceptionLabelValueProvider implements ErrorLabelValueProviderInterface
{
    public function __invoke(Envelope $envelope, StackInterface $stack, \Throwable $exception): array
    {
        /** @var FooMessage $message */
        $message = $envelope->getMessage();

        return [
            \get_class($message),
            substr(strrchr(get_class($message), '\\'), 1),
            $exception->getMessage()
        ];
    }
}

And the updated ServiceConfiguration

services:
    ...
    PrometheusMiddleware\Tests\Example\FooExceptionLabelValueProvider: ~

    PrometheusMiddleware\PrometheusMiddleware:
      arguments:
        $errorLabels: ['message', 'label','value']
        $errorLabelValueProvider: '@PrometheusMiddleware\Tests\Example\LabelValueProvider'

Full PrometheusMiddleware API

Property	Required	Description
CollectorRegistry $collectorRegistry	required	Underlying CollectorRegistry to generate and persist your metrics
string $metricName	optional	Default message, used as "name" for your Counter
string $helpText	optional	Default Executed Messages, used as Counter help text
array $labels	optional	Default ['message', 'label'], default provided Counter labels
LabelValueProviderInterface $provider	optional	Default DefaultLabelValueProvider, provides the Counter label related values
string $errorHelpText	optional	Default Failed Messages, used as Error Counter help text
array $errorLabels	optional	Default ['message', 'label'], default provided Error Counter labels
ErrorLabelValueProviderInterface $errorLabelValueProvider	optional	Default DefaultErrorLabelValueProvider, provides the Error Counter label related values