Quickstart for setting up LibreElec with Docker running Transmission as a low footprint RP4 based daily driver
Docker is installable as an add-on from LibreElec
The recommendation from the LE team is to use Docker and Portainer. I've found that option did not work that well. I got only 1 or 2 months uptime. The portainer setting fetched updates nightly and I don't need the instabiltiy that caused me. Sometimes I'd have to reboot, finally it crashed transmission. I've had Theoria's tranmission running for years with no outages on an old RP 2 Model B, I get the odd lock up but have a remote monitor and a remote control PSU to hard reset if the Transmission web interface is not visible for an extended period. This gives me zero touch transmission on old hardware
So why this update? I've a 4k Tv and noticed some content was taking a long time as the RP2B only has 100meg networking. RP4 has USB3 and 1g Networking.
BEFORE YOU START don't try to use USB Flash drives or SD cards for this. Use SSDs or HDs there is a lot of IO and SD cards and flash cannot take the write intensity plus there cannot keep up with SUSTAINED writes and concurrent reads.
Using the offical repo install docker (its under Add-ons services) then restart the RPI4, connect via SSH from a PC and enter the command below. Edit the -v commands to fit your setup in my case I've a USB drive plugged into a USB3 port on the RP4 (2m RAM) running of SD. Note how all my temp files are on the USB HD.
docker run -d
--name=9091-transmission
--net=host
-e PUID=0
-e PGID=0
-e TZ=Europe/London
-e USER=admin
-e PASS=secret
-p 9091:9091
-p 51413:51413
-p 51413:51413/udp
-v /var/media/10TB/_dockerrp4avroom/.config/dockers/transmission/config:/config
-v /var/media/10TB/:/downloads
-v /var/media/10TB/watch:/watch
-v /storage:/storage
-v /media:/media
--restart unless-stopped
linuxserver/transmission
If some of the setting are not what you wanted (take the time to test out a few small samples) you can stop the container and delete it, creating a new one with updated settings is fast. Once things are working as you want you can set them to run 24x7 unless manually stopped, restart will start the docker daemon and start the container on reboot
docker update --restart always $(docker ps -q)
If you are new to docker or need to polish up this is a good resource (scroll to the end for the more advanced commands)
Tranmission Temp files
Transmission keeps a mad cache in /storage/.kodi/userdata/addon_data/service.system.docker/docker (as we are running transmission in docker the files are stored in the overlay2 FS. You can't really delete the transmission cache, it but worse it writes it to SD card so the writes can wear the SD card causing it to fail after a 100k writes. This does not happen on SSDs or HD, even if you point the download directory to NAS. At this point you could reconfigure docker to run from a new location on HD / SSD not SD card (shutdown docker, point docker to start elsewhere, rsyhch the old to new locations, restart docker, details here: https://linuxconfig.org/how-to-move-docker-s-default-var-lib-docker-to-another-directory-on-ubuntu-debian-linux) or do what I did and set the RP4 to boot off HDD! I did this and restored my backup enven though I'd uninstalled docker add-on and rm -r the docker directory the docker cache was still around with images! If like me you need to flush your docker image cache, remove all containers etc this will help
docker ps -a docker rmi -f 'linuxserver/transmission:latest' docker ps -a docker rmi -f "9091-transmission" docker ls -a docker ps -a docker rm 30edd65c0872493cb350850b0f17c3fab67b403092f8e538639190f67820e872 docker ps -a docker ls -a docker image ls docker image rm linuxserver/transmission