Using counter type metric

On this page

  1. Using Counter Type Metric
  2. Cache Configuration

Overview

A Counter is a metric that only increases in value. It is typically used to count events, such as the number of requests received or tasks completed.

Creating a Counter

You can create a Counter metric using the addCounter method:

$counter = Prometheus::addCounter('my_counter');

Setting an Initial Value

You can also define an initial value for your counter when creating it. This is useful if you want to start counting from a specific number:

$counter = Prometheus::addCounter('my counter')->setInitialValue(100);

Incrementing the Counter

To increment the counter, you can use the inc method:

$counter->inc();

This will increase the counter by one.

If you need to increment the counter by a value greater than one, you can pass the value as an argument to the inc() method:

$counter->inc(2);

Best Practices

  • Naming Conventions: Use descriptive names for your counters to make it clear what they are tracking. For example, user_registration_total or api_request_count.
  • Atomic Increments: Ensure that increments are atomic, especially in multi-threaded or multi-process environments, to avoid race conditions.

By default, the cache setting is set to null, which means that the metric will be stored in memory without using Laravel's caching system. This is suitable for simple setups or testing environments.

You can configure the cache in the config/prometheus.php file:

/**
* Select a cache to store gauges, counters, summaries and histograms between requests.
* In a multi node setup you should ensure that each node writes to its own
* cache instance or uses a node specific prefix.
* Configure the cache store in config/cache.php.
*
* to use an in memory adapter for testing use array or null as your store
* or remove the cache entry all together:
*  'cache' => null       // InMemory implementation without laravel cache
*  'cache' => 'array'    // InMemory implementation using laravel cache
*/
'cache' => null,
  • In-Memory Cache: If you want to use an in-memory cache without relying on Laravel's cache system, keep the cache option as null.
  • Laravel Cache: To store metrics in Laravel's cache, set the cache option to a valid cache driver defined in your config/cache.php file: 
    'cache' => 'redis', // Using Redis for caching metrics

By properly configuring the cache, you can ensure that your metrics are persisted and shared across requests, making them more reliable in production environments.

Creating collectors
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