This is the source of my personal instance of torrent-fish - it helps people resolve magnet links to my torrents, in case there's nobody in the swarm currently.
torrent-fish is a metadata-only BitTorrent peer built with libtorrent. It's designed to help keep magnet links which rely on HTTP Seeding healthy, without the overhead of running other peers or seeds.
Today, it's deployed on Google Cloud using the free Compute Engine credits, which allows you to run a container seamlessly as if it were a regular instance using Google's COS image (docs). This is overkill for torrent-fish by a factor of about 10, but it's easy, and it's free.
Normally I would use Fly for deploying containers, Fly's network layer doesn't currently work well for torrent-fish given TCP and UDP need to be handled separately (source). They're working on it though - so this may move to Fly eventually.