Configuration options

Required environment options

Variable	Function	Example
OPENVPN_PROVIDER	Sets the OpenVPN provider to use.	OPENVPN_PROVIDER=provider. Supported providers and their config values are listed in the table above.
OPENVPN_USERNAME	Your OpenVPN username	OPENVPN_USERNAME=asdf
OPENVPN_PASSWORD	Your OpenVPN password, beware of special characters. Docker run vs docker-compose (using YAML) interpret special characters differently, see Yaml special characters	OPENVPN_PASSWORD=asdf

Docker secrets are available to define OPENVPN_USER and OPENVPN_PASSWORD.

• remove OPENVPN_USERNAME, OPENVPN_PASSWORD from environment.
• write your credentials in one file: openvpn_creds
• add to your compose YAML:

version: '3.8'
services:
 transmission:
    ....
    secrets:
        - openvpn_creds

secrets:
    openvpn_creds:
        file: ./openvpn_creds

Network configuration options

Variable	Function	Example
OPENVPN_CONFIG	Sets the OpenVPN endpoint to connect to.	OPENVPN_CONFIG=UK Southampton
OPENVPN_OPTS	Will be passed to OpenVPN on startup	See OpenVPN doc
LOCAL_NETWORK	Sets the local network that should have access. Accepts comma-separated list.	LOCAL_NETWORK=192.168.0.0/24
CREATE_TUN_DEVICE	Creates /dev/net/tun device inside the container, mitigates the need to mount the device from the host	CREATE_TUN_DEVICE=true
PEER_DNS	Controls whether to use the DNS provided by the OpenVPN endpoint.	To use your host DNS rather than what is provided by OpenVPN, set PEER_DNS=false. This allows for potential DNS leakage.
PEER_DNS_PIN_ROUTES	Controls whether to force traffic to peer DNS through the OpenVPN tunnel.	To disable this default, set PEER_DNS_PIN_ROUTES=false.

Timezone option

Set a custom timezone in tz database format. Look here for a list of valid timezones. Defaults to UTC.

Variable	Function	Example
TZ	Set Timezone	TZ=UTC

Firewall configuration options

When enabled, the firewall blocks everything except traffic to the peer port and traffic to the rpc port from the LOCAL_NETWORK and the internal docker gateway.

If TRANSMISSION_PEER_PORT_RANDOM_ON_START is enabled then it allows traffic to the range of peer ports defined by TRANSMISSION_PEER_PORT_RANDOM_HIGH and TRANSMISSION_PEER_PORT_RANDOM_LOW.

Variable	Function	Example
ENABLE_UFW	Enables the firewall	ENABLE_UFW=true
UFW_ALLOW_GW_NET	Allows the gateway network through the firewall. Off defaults to only allowing the gateway.	UFW_ALLOW_GW_NET=true
UFW_EXTRA_PORTS	Allows the comma-separated list of ports through the firewall. Respects UFW_ALLOW_GW_NET.	UFW_EXTRA_PORTS=9910,23561,443
UFW_DISABLE_IPTABLES_REJECT	Prevents the use of REJECT in the iptables rules, for hosts without the ipt_REJECT module (such as the Synology NAS).	UFW_DISABLE_IPTABLES_REJECT=true

Health check option

Because your VPN connection can sometimes fail, Docker will run a health check on this container every 5 minutes to see if the container is still connected to the internet. By default, this check is done by pinging google.com once. You change the host that is pinged.

Variable	Function	Example
HEALTH_CHECK_HOST	this host is pinged to check if the network connection still works	google.com

Permission configuration options

By default, the startup script applies a default set of permissions and ownership on the transmission download, watch and incomplete directories. The GLOBAL_APPLY_PERMISSIONS directive can be used to disable this functionality.

Variable	Function	Example
GLOBAL_APPLY_PERMISSIONS	Disable setting of default permissions	GLOBAL_APPLY_PERMISSIONS=false

Alternative Web UIs

This container comes bundled with some alternative Web UIs:

• Combustion UI
• Kettu
• Transmission-Web-Control
• Flood for Transmission
• Shift
• Transmissionic

To use one of them instead of the default Transmission UI you can set TRANSMISSION_WEB_UI to either combustion, kettu, transmission-web-control, flood-for-transmission, shift or transmissionic respectively.

Variable	Function	Example
TRANSMISSION_WEB_UI	Use the specified bundled web UI	TRANSMISSION_WEB_UI=combustion TRANSMISSION_WEB_UI=kettu TRANSMISSION_WEB_UI=transmission-web-control TRANSMISSION_WEB_UI=flood-for-transmission TRANSMISSION_WEB_UI=shift TRANSMISSION_WEB_UI=transmissionic

User configuration options

By default, everything will run as the root user. However, it is possible to change who runs the transmission process. You may set the following parameters to customize the user id that runs Transmission.

Variable	Function	Example
PUID	Sets the user id who will run transmission	PUID=1003
PGID	Sets the group id for the transmission user	PGID=1003

Transmission configuration options

In previous versions of this container the settings were not persistent but were generated from environment variables on container startup. This had the benefit of being very explicit and reproducible but you had to provide Transmission config as environment variables if you wanted them to stay that way between container restarts. This felt cumbersome to many.

As of version 4.2, this is no longer true. Settings are now persisted in the /config/transmission-home folder in the container and as long as you mount /config you should be able to configure Transmission using the UI as you normally would. If you are using the container from earlier versions and have not changed the location of transmission-home to /config, you will see a warning message that the default has changed. You can manually move the folder to your /config volume directory after stopping the container and adding the /config mount to your container setup (compose/run etc).

You may still override Transmission options by setting environment variables if that's your thing. The variables are named after the transmission config they target but are prefixed with TRANSMISSION_, capitalized, and - is converted to _.

For example:

Transmission variable name	Environment variable name
speed-limit-up	TRANSMISSION_SPEED_LIMIT_UP
speed-limit-up-enabled	TRANSMISSION_SPEED_LIMIT_UP_ENABLED
ratio-limit	TRANSMISSION_RATIO_LIMIT
ratio-limit-enabled	TRANSMISSION_RATIO_LIMIT_ENABLED

A full list of variables can be found in the Transmission documentation here.

All variables overridden by environment variables will be logged during startup.

PS: TRANSMISSION_BIND_ADDRESS_IPV4 will automatically be overridden to the IP assigned to your OpenVPN tunnel interface. This ensures that Transmission only listens for torrent traffic on the VPN interface and is part of the fail-safe mechanisms.

Dropping default route from iptables (advanced)

Some VPNs do not override the default route, but rather set other routes with a lower metric. This might lead to the default route (your untunneled connection) being used.

To drop the default route set the environment variable DROP_DEFAULT_ROUTE to true.

Note: This is not compatible with all VPNs. You can check your iptables routing with the ip r command in a running container.

Changing logging locations

By default, Transmission will log to a file in TRANSMISSION_HOME/transmission.log.

To log to stdout instead set the environment variable LOG_TO_STDOUT to true.

Note: By default, stdout is what container engines read logs from. Set this to true to have Transmission logs in commands like docker logs and kubectl logs. OpenVPN currently only logs to stdout.

Custom scripts

If you ever need to run custom code before or after Transmission is executed or stopped, you can use the custom scripts feature. Custom scripts are located in the /scripts directory which is empty by default. To enable this feature, you'll need to mount the /scripts directory.

Once /scripts is mounted you'll need to write your custom code in the following bash shell scripts:

Script	Function
/scripts/openvpn-pre-start.sh	This shell script will be executed before OpenVPN starts
/scripts/openvpn-post-config.sh	This shell script will be executed after OpenVPN config
/scripts/transmission-pre-start.sh	This shell script will be executed before transmission starts
/scripts/transmission-post-start.sh	This shell script will be executed after transmission starts
/scripts/routes-post-start.sh	This shell script will be executed after routes are added
/scripts/transmission-pre-stop.sh	This shell script will be executed before transmission stops
/scripts/transmission-post-stop.sh	This shell script will be executed after transmission stops

Don't forget to include the #!/bin/bash shebang and to make the scripts executable using chmod a+x

Debugging

By default, commands are not echoed to stdout before being processed. Setting DEBUG to any value other than the string false will trigger command echo (set -x) for all bash scripts.

Variable	Function	Example
DEBUG	Echo all commands to stdout.	DEBUG=true