pyunramura/transmission

How to use this image

This container is configured to be used in conjunction with my OpenVPN client and set up for automatic out-of-the-box port-forwarding to capable private internet access servers for faster downloads. Additional support for port-forwarding capable vpn providers can be added on request. Feedback is welcome and encouraged as I'm always looking to improve my containers.

Transmission is an amazingly simple but powerful open-source torrent client that is heavily optimized to run on devices ranging from server-grade architectures to energy-efficient arm devices. It forgoes some of the bells and whistles of other torrent clients in favor of a streamlined process that is light on resources, so it is a shoe-in for use in docker containers. To learn more about it, visit its webpage at transmissionbt.com

This image is based on Alpine Linux with s6-overlay and optimized to be light-weight and feature robust process management. Additionally this container is heavily modeled after the fantastic linuxserver.io containers, but with added features and more aggressive space-saving techniques.

Usage Example with a VPN

docker run -d --rm \
  --name=transmission \
  --net=container:openvpn \
  -v path/to/config/data:/config \
  -v path/to/downloads:/downloads \
  -v path/to/watch/dir:/watch \
  -v vpn_port:/var/run/openvpn \
  -e GID=783 -e UID=783 \
  -e VPN=yes -e PORT_F=yes \
  -e NEW_UI=yes 
  pyunramura/transmission

Usage Example without a VPN

docker run -d --rm \
  --name=transmission \
  -p 9091:9091 -p 51413:51413 \
  -p 51413:51413/udp \
  -v path/to/config/data:/config \
  -v path/to/downloads:/downloads \
  -v path/to/watch/dir:/watch \
  -e GID=783 -e UID=783 \
  -e NEW_UI=yes 
  pyunramura/transmission

Parameters

The parameters below are split into two halves, separated by a colon, the left hand side representing the host and the right the container side.

For example with -p external:internal - what this shows is the port mapping from external to internal of the container. So -p 80:9091 would expose port 9091 from inside the container to be accessible from the host's IP on port 80 http://192.168.x.x:80 would show you what's running INSIDE the container on port 9091.

-p 9091 - the default port for the transmission-web UI
-p 51413 - the default peer port for use in non vpn based port forwarding
-v /config - where transmission will store its configuration files and logs
-v /downloads - for your local path for downloaded torrents
-v /watch - the folder for dropped-in .torrent files to be automatically picked up by transmission
-v vpn_port - a docker volume made with docker create volume to retrieve the peer port if used with my OpenVPN container
-e GID - for GroupID - see below for explanation
-e UID - for UserID - see below for explanation
-e VPN - if set to yes, the container will automatically attach itself to a connected open vpn tunnel, and kill the connection if it goes down
-e PORT_F - if set to yes, your peer port will be dynamically updated if used along-side my OpenVPN container
-e NEW_UI - if set to yes, enables Secretmapper's modern Combustion UI in place of the default transmission-web UI

Notes from above

The 51413 port-mapping is only useful for peer-peer communication when running standalone, it can be forwarded through your firewall, or UPnP if needed.
The default ports are not needed for the --net=container:openvpn option, they will be mapped to it instead. If you are using this option in a docker-compose file it would instead read network_mode: service:openvpn. A sample compose file is in the openvpn repository for reference.
The container implements a kill switch to rebind the service to localhost if the vpn tunnel collapses as an additional privacy measure against leaking unwanted data. This is set to run every 10 minutes at default and can be changed if requested.

User / Group Identifiers

Sometimes when using data volumes (-v flags) permissions issues can arise between the host OS and the container. This is avoided by allowing you to specify the user UID and group GID. Ensure the data volume directory on the host is owned by the same user you specify and it will "just work" ™.

In this instance for UID=1001 and GID=1001. To find yours, use id user as below:

  $ id <dockeruser>
    uid=1001(dockeruser) gid=1001(dockergroup) groups=1001(dockergroup)

Setting up the application

The transmission-web UI is on port 9091, the settings.json file in /config has extra settings not available in the web UI. You will need to stop the container before editing it or your changes won't be saved.

There are many more configuration options housed in Transmission's settings.json that can be edited as you see fit. The guide for this can be found at the Transmision Github Wiki.

Securing the web UI with a username and password.

This requires 3 settings to be changed in the settings.json file.

Make sure the container is stopped before editing these settings.

"rpc-authentication-required": true, - check this, the default is false, change to true.

"rpc-username": "transmission", substitute transmission for your chosen user name, this is just an example.

rpc-password will be a hash starting with {, replace everything including the { with your chosen password, keeping the quotes.

Transmission will convert it to a hash when you restart the container after making the above changes.

Updating blocklists Automatically

This setting requires "blocklist-enabled": true, to be set in the settings.json. By setting this to true, it is assumed you have also populated blocklist-url with a valid block list.

The automatic update will run once a day at 3am local server time.

This setting should not be necessary if used behind a vpn.

Info

For shell access while the container is running

docker exec -it transmission /bin/sh.
To monitor the logs of the container in realtime

docker logs -f transmission.
For the container version number

docker inspect -f '{{ index .Config.Labels "build_version" }}' transmission.
For the image version number

docker inspect -f '{{ index .Config.Labels "build_version" }}' pyunramura/transmission.

Troubleshooting

Initial setup

You will need to start, then stop the container in order to generate the settings.json in order to edit the file.

If you will not be needing to traffic your torrents through the VPN, leave -e VPN unset as it will trigger the container to fail and exit if not set to yes. This is designed as a check to make sure that you want to enable the kill switch that the -e VPN=yes option enables.

If you have any other problems or comments about using this container, please reach out to me through the "Issues" tab as feedback and bug reports are welcome and encouraged.

Versions

2.9.4-r0 - Initial Release.

pyunramura / docker-transmission