Simple multi-domain counter with Redis and PHP

Imagine you have multiple domains on your server and you want to add a simple counter to count views and visits.

In this tutorial, I’m going to describe how to implement views and visits counter with PHP and Redis. It would be the most simple solution without bots detection, just visits and views. So, let's start!

First, install phpredis extention via composer:

    composer require predis/predis

Now let's write getUserIp() function, which gets visitor ip address:

function getUserIP() {
    $user_ip = getenv('REMOTE_ADDR')
    or getenv('HTTP_CLIENT_IP')
    or $user_ip = getenv('HTTP_X_FORWARDED_FOR');

    return preg_replace('|[^0-9.]+|', '', $user_ip); // only digits and dots allowed
}

Initialize Redis, get IP and set up domain address:

$client = new Predis\Client(); 
$user_ip = getUserIP();
$domain = 'yourdomain';

Now, when all preparation is done, let's move to the counting:

if (!$client->sismember("ips:$domain", $user_ip)) { // if no ip in ips:subdomain
    $client->hincrby("stat:$domain", 'visits', 1); // add visit
    $client->sadd("ips:$domain", [$user_ip]); // add ip to the set
}
$client->hincrby("stat:$domain", 'views', 1); // add view

We used Redis Sets (collections of unique, unsorted string elements) to store IP addresses and Hashes (maps composed of fields associated with values) for counting.

Now to get counted visits and views use hget() function:

echo 'visits: ' . $client->hget("stat:$domain", 'visits') . '<br>';
echo 'views: ' . $client->hget("stat:$domain", 'views') . '<br>';

And don't forget to store values and flush Redis (flushall command) at the end of the day.