Missing YouTube video thumbnails [fixed]

Necropola❌@lemmy.world · edit-2 1 year ago

Missing YouTube video thumbnails [fixed]

Meldrik · 2 years ago

Exactly.

Necropola❌@lemmy.world · edit-2 2 years ago

That’s really weird. I already went through the issue tracker on GitHub for both the lemmy backend as well as the frontend, but couldn’t find anything. I also checked the documentation whether there is a configuration option somewhere. Nothing.

My guess is that the thumbnail is extracted (read from the opengraph tag available via the posted URL) in the frontend (and not the backend).

The only thing I could find on the issue tracker which might be related is this:

https://github.com/LemmyNet/lemmy-ui/issues/709

Meldrik · edit-2 2 years ago

I have no idea why it is happening. The only thing I can think of is Cloudflare tunnel, but why would that keep the thumbnails from loading? I send a message to the admin of Lemmy.world.

edit: I am also trying to troubleshoot why users from kbin.social can’t subscribe to here and vice versa.

Necropola❌@lemmy.world · 2 years ago

I was able to subscribe from lemmy.world to kbin.social (yesterday or the day before). I tried it on another account from feddit.de today and it did not work. My guess is a problem at kbin.social.

Meldrik · edit-2 2 years ago

This works:

This doesn’t work:

The difference between the two communities at lemmy.world, is that c/selfhosted has been around for a long time and c/xcode was created just a few days ago. It seems that only communities that initially connected with kbin.social work, but not new communities.

Necropola❌@lemmy.world · edit-2 2 years ago

I see you have been discussing this with the people & mod of the GW2 magazine on kbin.social already. To me it really seems to be an issue on their side. As I mentioned above: I currently cannot subscribe from feddit.de to their guildwars2 magazine, either.

Necropola❌@lemmy.world · 2 years ago

I also found this

https://github.com/LemmyNet/lemmy-ui/issues/20

There is an environment variable LEMMY_UI_DISABLE_CSP (default : false) to configure lemmy-ui. Do you set this on your instance or do you set a Content-Security-Policxy Header somewhere in your webserver/nginx config?

Meldrik · 2 years ago

I just use the settings as it is shown in the installation guide for Docker: https://join-lemmy.org/docs/en/administration/install_docker.html

Necropola❌@lemmy.world · edit-2 2 years ago

OK. Looks like the CSP headers are the same on working and not working instances.

What I found surprising is that chrome loads the thumbnail without accessing the actual YT URL (contrary to what I expected) from the “pictrs” server of the instance serving the post. Which means that the thumbnail gets only extracted once and is then stored along with the post.

Necropola❌@lemmy.world · edit-2 2 years ago

Brainstorming

Thumbnail extraction definitely happens in the backend.
- But when does it happen?
- Only when creating the post?
- Or also when federating a post to a new instance?
- PR which replaced iframely ➡ https://github.com/LemmyNet/lemmy/pull/1706
- Now backend uses fetch_site_metadata ➡ https://github.com/LemmyNet/lemmy/blob/main/crates/api_common/src/request.rs
- … whenever a post is created or updated
Thumbnails do neither work on lemmy.wtf nor lemmy.world but work on feddit.de
- Does feddit.de extract the missing thumbnail when creating/updating the post?
- Or does it expect the thumbnail to be transmitted alongside the post?
lemmy.world does not use cloudflare (I think) but they are also (like lemmy.wtf) using docker (I think)

Also Not Working on lemmy.world

https://lemmy.world/c/music

But does on feddit.de

https://feddit.de /c/music@lemmy.world

It’s not only YT thumbnails which aren’t shown. This is your post about the free 24 slot bag as shown on lemmy.wtf (no thumbnail), lemmy.world (no thumbnail) and feddit.de (with thumbnail):