A prometheus client library written in PHP

This library uses Redis or APCu to do the client side aggregation. If using Redis, we recommend to run a local Redis instance next to your PHP workers.

How does it work?

Usually PHP worker processes don't share any state. You can pick from three adapters. Redis, APC or an in memory adapter. While the first needs a separate binary running, the second just needs the APC extension to be installed. If you don't need persistent metrics between requests (e.g. a long running cron job or script) the in memory adapter might be suitable to use.

Usage

A simple counter:

\Prometheus\CollectorRegistry::getDefault()
    ->getOrRegisterCounter('', 'some_quick_counter', 'just a quick measurement')
    ->inc();

Write some enhanced metrics:

$registry = \Prometheus\CollectorRegistry::getDefault();

$counter = $registry->getOrRegisterCounter('test', 'some_counter', 'it increases', ['type']);
$counter->incBy(3, ['blue']);

$gauge = $registry->getOrRegisterGauge('test', 'some_gauge', 'it sets', ['type']);
$gauge->set(2.5, ['blue']);

$histogram = $registry->getOrRegisterHistogram('test', 'some_histogram', 'it observes', ['type'], [0.1, 1, 2, 3.5, 4, 5, 6, 7, 8, 9]);
$histogram->observe(3.5, ['blue']);

Manually register and retrieve metrics (these steps are combined in the getOrRegister... methods):

$registry = \Prometheus\CollectorRegistry::getDefault();

$counterA = $registry->registerCounter('test', 'some_counter', 'it increases', ['type']);
$counterA->incBy(3, ['blue']);

// once a metric is registered, it can be retrieved using e.g. getCounter:
$counterB = $registry->getCounter('test', 'some_counter')
$counterB->incBy(2, ['red']);

Expose the metrics:

$registry = \Prometheus\CollectorRegistry::getDefault();

$renderer = new RenderTextFormat();
$result = $renderer->render($registry->getMetricFamilySamples());

header('Content-type: ' . RenderTextFormat::MIME_TYPE);
echo $result;

Change the Redis options (the example shows the defaults):

\Prometheus\Storage\Redis::setDefaultOptions(
    [
        'host' => '127.0.0.1',
        'port' => 6379,
        'password' => null,
        'timeout' => 0.1, // in seconds
        'read_timeout' => 10, // in seconds
        'persistent_connections' => false
    ]
);

Using the InMemory storage:

$registry = new CollectorRegistry(new InMemory());

$counter = $registry->registerCounter('test', 'some_counter', 'it increases', ['type']);
$counter->incBy(3, ['blue']);

$renderer = new RenderTextFormat();
$result = $renderer->render($registry->getMetricFamilySamples());

You can now add default metrics (e.g. environment variables).

This can be especially useful in situations like CLI applications with APC adapter, that does not share the same memory for fpm and all the other CLI processes.

In this case the use of push gateway comes in handy, but makes it hard to pass metrics that remain static.

applyDefaultLabels aims to bridge this gap, by giving you the ability to add default configuration:

$registry = new CollectorRegistry(new InMemory());

$registry->applyDefaultLabels(['host' => $_SERVER['SERVER_NAME']]);

Also look at the examples.

Development

Dependencies

PHP >7.2
PHP Redis extension
PHP APCu extension
Composer
Redis

Start a Redis instance:

docker-compose up Redis

Run the tests:

composer install

# when Redis is not listening on localhost:
# export REDIS_HOST=192.168.59.100
./vendor/bin/phpunit

Black box testing

Just start the nginx, fpm & Redis setup with docker-compose:

docker-compose up

Pick the adapter you want to test.