Edit: Solved! Thanks a ton non_burglar.

Good day selfhost gang!

I'm redoing my media stack and I've come across a conundrum that I can't solve on my own. I've got Docker containers on the same Debian machine for qbittorrent, sonarr, and radarr for automatic media downloading. The problem is, as you may have guessed from the title, I need to implement remote path mapping in sonarr/radarr because qbittorrent downloads to a different location than where my media files are hosted. My media is hosted on a network share, mounted at /home/marighost/gilashare/media (which is further broken into subfolders for media types). On this machine, however, I've got my qbittorrent downloading to a 2Tb SSD at /srv/data/torrents. Here are the volumes as presented in my compose.yml files:

qbittorrent:  
    volumes:  
      - /home/marighost/docker/seedbox/gluetunconfig:/gluetun  
      - /home/marighost/docker/seedbox/qbittorrentconfig:/config  
      - /srv/data/torrents:/data/torrents  

sonarr:  
    volumes:  
      - /home/marighost/docker/arrstack/sonarrconfig:/config  
      - /home/marighost/gilashare/media:/tv  
      - /srv/data/torrents:/data  

radarr:  
    volumes:  
      - /home/marighost/docker/arrstack/sonarrconfig:/config  
      - /home/marighost/gilashare/media/movies:/movies  
      - /srv/data/torrents:/data  

All three applications work mostly as expected (radarr can grab a release from an indexer, throws it into qbittorrent to download), but it does not move media into the /gilashare subfolder.

Obviously, I get the error in both sonarr and radarr that tells me:
You are using docker; download client qBittorrent places downloads in /data/torrents but this directory does not appear to exist inside the container. Review your remote path mappings and container volume settings.

Here is how my remote path mapping looks in the settings of sonarr/radarr:

Host: qbittorrent  
Remote Path: /srv/data/torrents/  
Local Path: /data/  

I was messing around with radarr initially, and also tried appending /movies to the ends of the Remote and Local paths to see if it needed the full path, but that didn't seem to work either. I've also read through Trash Guides, but the information there seems outdated (all references to images are just... not there). I've also read radarr's docs, but I feel like I'm missing something, and they just link to Trash Guides anyway.

Thanks for reading, happy to dig into my configs or setup more if necessary.

1st thing to check is permissions, I have seen radarr/sonarr complain about the path "not existing", but actually the download client process had no write permission to the destination.

From the radarr wiki:

Generally, a remote path map is only required if your download client is on Linux when *Arr is on Windows or vice versa. A remote path map is also possibly needed if mixing Docker and Native clients or if using a remote server.

Since radarr >4.x, there hasn't been a need for remote path between Linux machines, not sure about sonarr, but they are similar.

Now for your case, your qbittorrent host does not know about /srv/ in its path, it only knows about /data and everything under it:

qbittorrent:  
    volumes:  
      - /home/marighost/docker/seedbox/gluetunconfig:/gluetun  
      - /home/marighost/docker/seedbox/qbittorrentconfig:/config  
      - /srv/data/torrents:/data/torrents

So when radarr tells

Host: qbittorrent  
Remote Path: /srv/data/torrents/  
Local Path: /data/ 

qbittorrent, which lives inside its docker world, has no idea what /srv means.

Thanks for the reply. I believe I have permissions set correctly, as qbit was the first thing I set up and had to fiddle with permissions under the /srv/data/torrents folder to test if downloads worked.

I understood "remote path mapping" to also include filesystems on other machines, even if it's a LAN connection. Maybe that's true? because I simple changed the Remote Path mapping in radarr from /srv/data/torrents to just /data/torrents, and the movie I had sitting in the queue (which successfully downloaded from radarr to qbit, just didn't move from qbit to media) moved to my media folder upon restarting radarr.

I knew it had to be simple. Thank you, and I hope you have a great week!

No worries, and I'm glad it helped!

I'll add that I was also mystified by the remote path option for a long time, I think the wiki should show more clearly what this does and maybe an example.

Also, I used to run into issues of running into permissions errors because the download client wrote the files with the wrong permissions. Many nzb and torrent clients have a POSIX masking option that allows you to set the permissions at the time of writing.

You said radarr, sonarr, and qbit are all on docker on the same host, right? The correct fix is to remove the remote path mapping and fix the volumes for the arrs to be /srv/data:/data or /srv/data/torrents:/data/torrents.

Your path for /tv should also be more like radarr has, where instead of the host path ending in media, it should end in media/tv