syncthing/README-Docker.md

Docker Container for Syncthing

Use the Dockerfile in this repo, or pull the syncthing/syncthing image from Docker Hub.

Use the /var/syncthing volume to have the synchronized files available on the host. You can add more folders and map them as you prefer.

Note that Syncthing runs as UID 1000 and GID 1000 by default. These may be altered with the PUID and PGID environment variables. In addition the name of the Syncthing instance can be optionally defined by using --hostname=syncthing parameter.

Example Usage

Docker cli

$ docker pull syncthing/syncthing
$ docker run --sysctl net.core.rmem_max=2097152 \
    -p 8384:8384 -p 22000:22000/tcp -p 22000:22000/udp \
    -v /wherever/st-sync:/var/syncthing \
    --hostname=my-syncthing \
    syncthing/syncthing:latest

Docker compose

---
version: "3"
services:
  syncthing:
    image: syncthing/syncthing
    container_name: syncthing
    hostname: my-syncthing
    environment:
      - PUID=1000
      - PGID=1000
    volumes:
      - /wherever/st-sync:/var/syncthing
    ports:
      - 8384:8384
      - 22000:22000/tcp
      - 22000:22000/udp
    sysctls:
      - net.core.rmem_max=2097152
    restart: unless-stopped

Discovery

Note that local device discovery will not work with the above command, resulting in poor local transfer rates if local device addresses are not manually configured.

To allow local discovery, the docker host network can be used instead:

$ docker pull syncthing/syncthing
$ docker run --network=host \
    -v /wherever/st-sync:/var/syncthing \
    syncthing/syncthing:latest

Be aware that syncthing alone is now in control of what interfaces and ports it listens on. You can edit the syncthing configuration to change the defaults if there are conflicts.

GUI Security

By default Syncthing inside the Docker image listens on 0.0.0.0:8384 to allow GUI connections via the Docker proxy. This is set by the STGUIADDRESS environment variable in the Dockerfile, as it differs from what Syncthing would otherwise use by default. This means you should set up authentication in the GUI, like for any other externally reachable Syncthing instance. If you do not require the GUI, or you use host networking, you can unset the STGUIADDRESS variable to have Syncthing fall back to listening on 127.0.0.1:

$ docker pull syncthing/syncthing
$ docker run -e STGUIADDRESS= \
    -v /wherever/st-sync:/var/syncthing \
    syncthing/syncthing:latest

With the environment variable unset Syncthing will follow what is set in the configuration file / GUI settings dialog.