Retries persist forever if blocked by adblocker

[chasegiunta]

I'm aware that using the reverse proxy might be a workaround to this, but at the same time, I think this should be addressed. I'd think this would be a configurable option in the client. Also, might be related, it looks like the retry param isn't being updated in these failed requests?

This is Firefox using the PrivacyBadger extension (I'm not a user myself, but we found out pretty quickly after deploying the JS client that a gigantic number of our users are themselves)

[rafaeelaudibert]

Hey, @chasegiunta! Are you sure posthog-js is retrying always the same request? Are the payloads exactly the same?

Also, would you mind calling posthog.debug() and showing me what's being logged to the console?

I can help you with that if you could share me a URL where I can see that behavior myself?

[chasegiunta]

Hey @rafaeelaudibert, thanks for getting back to me so quick! Unfortunately, we had to remove the frontend client from our live application for now.

Here's debug output

And here are some more requests.

I believe there's a few initial ones that are blocked, which seem fine, but the others that are repetitive at the bottom, all seem to be exactly the same. (all with retry_count=1 params) Firefox does not actually show a payload.

[rafaeelaudibert]

Yeah, it's not displaying the payload because this is the initial HEAD request, it's failing before we can actually POST the data. We'll investigate further, but I can't promise on a deadline, thank you!

[Julien-Marcou]

We had the same issue about a year ago, I think this ticket is talking about the same issue: #482
I guess it's something that could also happens if posthog's servers are down for whatever reason.

PostHog being blocked by an adblocker is not necessary a problem, until we want to do A-B testing on our entire platform using feature flags.

Because of the adblocker, the onFeatureFlags() callback would never be called, which means we were leaving our users on an infinite loading blank screen.
So we had to add a global timeout on our own, to fallback to a default feature flag value to resolve the blank screen issue.

It would be nice to have this behavior directly configurable within posthog, with something like a "max retry" or "timeout", and an error callback on the onFeatureFlags method:

// example
import posthog from 'posthog-js';

posthog.init(token, { retries: 3 });

posthog.onFeatureFlags({
  loaded: (flags, variants) => {
    // feature flags are properly loaded
  },
  error: () => {
   // fallback when we cannot load the feature flags
  },
});