Interesting, I know personally one of my concerns with self-hosting an individual Lemmy instance (after losing my first account to the Vlemmy.net shutdown) was the threat of being held legally responsible for things cached on the server. Say someone uploads something illegal and my server caches it. Seeing it as an option to turn that off is nice, and for an instance only meant to be used by one person I’d imagine caching won’t have a huge impact on load times
This got me thinking, does Lemmy clear orphan pictrs files? Say a user uploads an image but never submits the comment/post? That file is still on your pictrs and publicly linkable. And what if the post or comment is removed by moderator or deleted by the author? Is Lemmy cleaning these up?
This also helps mitigate the risk of people posting CSAM to attack other communities which your instance is subscribed to right? If you instance never cached the image, there’s no clean-up you have to do on your end provided the original instance removes the image from their server.
As you’ve mentioned, it makes sense for larger instances to have a cache, but smaller instance (especially single-user instances) may actually be better off not caching at all and just hosting their own images. As a more long-term solution which can add to this patch, it would be good if Lemmy did 2 things:
Separated the image cache for images from other instances so it can be cleared automatically on a schedule. E.g. Images which are a local cache are deleted after X days. Yes there are proper caching algorithms used in filesystems which would be better long-term, but a quick solution for this is probably better than no solution.
Periodically check for images which were uploaded by your own users to see if they are being referenced by any posts or comments. If not, delete them. I would imagine this could be a fairly intense operation so limiting this more fine-grained approach to images uploaded by your own users and taking the more liberal approach with cached images may help performance.
Holy shit, alright, I think I might be interested in this. I also have a growing storage problem that would need to solve. How does a patched instance look? Do you still see thumbnails? Can you share a screenshot?
Thanks for sharing! I see it takes a few ms to load the thumbnail but it’s a worthy tradeoff if it saves that much in storage. I’ll save this post and come back to your PR once it gets merged in, too lazy to apply it myself. :)
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