Adding these lines to my application.env covered this issue

# do not fetch external resources
DISABLE_FETCH_PREVIEWS=true
DISABLE_EMBED_PREVIEW=true

I will need to go through my own feed next to ensure that there are no embeds left over. This is in addition to my recent purging of boosts: https://mastodon.mariobreskic.de/@mario/114982417840616548

#server #asca #mastodon #gdpr

And from there, I delete all #PreviewCards in #mastodon by using these commands:

1. docker compose exec web bash
2. RAILS_ENV=production bundle exec rails console
And then I run this in the console: PreviewCard.destroy_all

This will run for a while but it should remove all stored preview cards from my mastodon server, for all posts.
And it worked. Just climb back up to my prompt by punching in “exit” until I am back home, and that issue has been fixed as well. #server #asca #mastodon #gdpr

Correction, see #aside here https://mastodon.mariobreskic.de/@mario/115050605879471525

#aside and #tldr
Running a solo Mastodon instance? Here's how to keep it clean and #gdpr compliant:
– Disable link previews: DISABLE_FETCH_PREVIEWS=true
– Purge old PreviewCards via Rails console
– Avoid federated content
– Self-author everything
– Host locally, anonymize IPs
Respectful publishing, no third-party hosting
#asca #server #mastodon #selfhosted #germany

There seems to be a bug implementing this in #mastodon #v4.4.3, so here is the workaround for disabling fetch previews by deleting preview_cards from the DB:

DELETE FROM preview_cards;

And blocking future inserts:

CREATE OR REPLACE FUNCTION block_preview_card_insert()
RETURNS trigger AS $$
BEGIN
-- Ignore insert
RETURN NULL;
END;
$$ LANGUAGE plpgsql;

CREATE TRIGGER prevent_preview_card_insert
BEFORE INSERT ON preview_cards
FOR EACH ROW
EXECUTE FUNCTION block_preview_card_insert();

Undoing the previous changes inside the db container, due to having found a more promisingly elegant solution:

DROP TRIGGER IF EXISTS prevent_preview_card_insert ON preview_cards;

DROP FUNCTION IF EXISTS block_preview_card_insert();

Fix:
adding this to my yaml file for my sidekiq and my web container:

command: >
bash -c "bundle exec rails runner 'class FetchLinkCardService; def call(*args); nil; end; end' &&
bundle exec puma -C config/puma.rb"

and sidekiq

command: >
bash -c "bundle exec rails runner 'class FetchLinkCardService; def call(*args); nil; end; end' &&
bundle exec sidekiq"

Filed a bug: https://github.com/mastodon/mastodon/issues/35813

Which is also a test for the patch ;)

#server #asca #mastodon #gdpr #PreviewCards

I need another test, as a sanity check:

https://de.wikipedia.org/