Missing YouTube video thumbnails [fixed]

Necropola❌ · edit-2 1 year ago

Missing YouTube video thumbnails [fixed]

Necropola❌ · 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❌ · 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❌ · 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
- … which evaluates the opengraph (og:*) meta tags from a linked HTML document 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? ➡ Yes, I think so
- Or does it expect the thumbnail to be transmitted alongside the post? ➡ No, I don’t think so
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/[email protected]

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):