Service Worker - Push notification with VAPID prv/pub keys - push-notification

Question

A couple of years ago I implemented push notification with service worker on a project I was working on, by registering an app on Firebase, and using the registration number as part of the manifest.json file on the server side app. In that case I requested the user to allow notifications, got the browser registration once, saved on server side, and all works fine.
I'm now trying to implement a similar solution, but using the VAPID (https://developers.google.com/web/ilt/pwa/introduction-to-push-notifications#using_vapid).
Browser registers correctly, sends the registration to the server side app, and the app is able to send push notifications.
The issue I got is that after at least 24 hours, when I try to send a push notification to an already registered subscription, I get InvalidSubscription response (410 NotRegistered).
Using VAPID, does the browser registration expire after a few hours? do I need to get new registration every certain amount of hours? If yes, how? For example, if user never revisits the site within a day or so, how am I able to keep sending them notifications? I can't find any clear reference for this issue I'm experiencing.
Here is the JS code I use within the SW to get the browser registration:
function postPushReg(sub){
var rawKey = sub.getKey ? sub.getKey('p256dh') : '';
var key = rawKey ?
btoa(String.fromCharCode.apply(null, new Uint8Array(rawKey))) :
'';
var rawAuthSecret = sub.getKey ? sub.getKey('auth') : '';
var authSecret = rawAuthSecret ?
btoa(String.fromCharCode.apply(null, new Uint8Array(rawAuthSecret))) :
'';
fetch('https://XXXXX', {
method: 'post',
headers: {'Content-type': 'application/json'},
body: JSON.stringify({endpoint: sub.endpoint, key: key, authSecret: authSecret}),
});
}
self.addEventListener('install', function(event){
self.registration.pushManager.getSubscription()
.then(function(sub){
if (sub) return postPushReg(sub);
return self.registration.pushManager.subscribe({userVisibleOnly: true,
applicationServerKey: urlB64ToUint8Array('XXX')})
.then(function(sub){
postPushReg(sub);
});
});
});
self.addEventListener('push', function(e){
...
});
This is the Rails/Ruby server side gem (webpush) I use to send the notification:
Webpush.payload_send(
message: "msg",
endpoint: j['endpoint'],
p256dh: j['key'],
auth: j['authSecret'],
vapid: {
subject: "mailto:XXXX",
public_key: "XXX",
private_key: "XXX",
}
)
Again, within the first few hours everything works, then I get 410 NotRegistered response.

Answer 1

Trying the same suggestion posted here: Web Push with VAPID: 400/401 Unauthorized Registration , it is now working fine. I get the browser registration only once, and after 2 days it is still working fine