$ composer require minishlink/web-push

$ openssl ecparam -genkey -name prime256v1 -out private_key.pem
$ openssl ec -in private_key.pem -pubout -outform DER|tail -c 65|base64|tr -d '=' |tr '/+' '_-' >> public_key.txt
$ openssl ec -in private_key.pem -outform DER|tail -c +8|head -c 32|base64|tr -d '=' |tr '/+' '_-' >> private_key.txt

$vapidKeysInBase64 = VAPID::createVapidKeys();

function checkNotificationSupported() {
  return new Promise((fulfilled, reject) => {
    if (!('serviceWorker' in navigator)) {
      reject(new Error('Service workers are not supported by this browser'));
      return;
    }
    if (!('PushManager' in window)) {
      reject(new Error('Push notifications are not supported by this browser'));
      return;
    }
    if (!('showNotification' in ServiceWorkerRegistration.prototype)) {
      reject(new Error('Notifications are not supported by this browser'));
      return;
    }
    fulfilled();
  })
}

navigator.serviceWorker.register('sw.js').then(() => {
      console.log('[SW] Service worker has been registered');
    }, e => {
      console.error('[SW] Service worker registration failed', e);
    }
  );

function checkNotificationPermission() {
    return new Promise((fulfilled, reject) => {
        if (Notification.permission === 'denied') {
            return reject(new Error('Push messages are blocked.'));
        }
        if (Notification.permission === 'granted') {
            return fulfilled();
        }
        if (Notification.permission === 'default') {
            return Notification.requestPermission().then(result => {
                if (result !== 'granted') {
                    reject(new Error('Bad permission result'));
                } else {
                    fulfilled();
                }
            });
        }
        return reject(new Error('Unknown permission'));
    });
}

<script>
  window.applicationServerKey = '<?= $yourPublicKeyFromServer ?>'
</script>

document.addEventListener('DOMContentLoaded', documentLoadHandler);
function documentLoadHandler() {
    checkNotificationSupported()
        .then(() => {
          setTimeout(() => {
            serviceWorkerRegistration.pushManager.subscribe({
                    userVisibleOnly: true,
                    applicationServerKey: urlBase64ToUint8Array(window.applicationServerKey),
                })
                .then(successSubscriptionHandler, errorSubscriptionHandler)
          }, 10000);
         },
          console.error
        );
}
function urlBase64ToUint8Array(base64String) {
    const padding = '='.repeat((4 - (base64String.length % 4)) % 4);
    const base64 = (base64String + padding).replace(/\-/g, '+').replace(/_/g, '/');
    const rawData = window.atob(base64);
    const outputArray = new Uint8Array(rawData.length);
    for (let i = 0; i < rawData.length; ++i) {
        outputArray[i] = rawData.charCodeAt(i);
    }
    return outputArray;
}
function errorSubscriptionHandler(err) {
    if (Notification.permission === 'denied') {
        console.warn('Notifications are denied by the user.');
    } else {
        console.error('Impossible to subscribe to push notifications', err);
    }
}

function successSubscriptionHandler(subscriptionData) {
    const key = subscription.getKey('p256dh');
    const token = subscription.getKey('auth');
    const contentEncoding = (PushManager.supportedContentEncodings || ['aesgcm'])[0];
    const body = new FormData();
    body.set('endpoint', subscription.endpoint);
    body.set('publicKey', key ? btoa(String.fromCharCode.apply(null, new Uint8Array(key))) : null);
    body.set('authToken', token ? btoa(String.fromCharCode.apply(null, new Uint8Array(token))) : null);
    body.set('contentEncoding', contentEncoding);
    return fetch('src/push_subscription.php', {
      method,
      body,
    }).then(() => subscription);
  }

self.addEventListener('push', function (event) {
    if (!(self.Notification && self.Notification.permission === 'granted')) {
        return;
    }
    const sendNotification = body => {
        const title = "Заголовок уведомления";
        return self.registration.showNotification(title, {
            body,
        });
    };
    if (event.data) {
        const message = event.data.text();
        event.waitUntil(sendNotification(message));
    }
});

<?php
$subscription = $_POST;
if (!isset($subscription['endpoint'])) {
    echo 'Error: not a subscription';
    return;
}
// save subscription from => $subscription

<?php
use Minishlink\WebPush\WebPush;
use Minishlink\WebPush\Subscription;
$subscription = Subscription::create($subscriptionData);

<?php
$auth = array(
    'VAPID' => array(
        'subject' => 'https://your-project-domain.com',
        'publicKey' => file_get_contents(__DIR__ . '/your_project/keys/public_key.txt'),
        'privateKey' => file_get_contents(__DIR__ . '/your_project/keys/private_key.txt'),
    )
);

<?php
$webPush = new WebPush($auth);

<?php
$report = $webPush->sendOneNotification(
  $subscription,
  "Тело пуш уведомления, оно поступило в тело sw.js"
);