# 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. To grant Syncthing additional capabilities without running as root, use the `PCAP` environment variable with the same syntax as that for `setcap(8)`. For example, `PCAP=cap_chown,cap_fowner+ep`. ## Example Usage **Docker cli** ``` $ docker pull syncthing/syncthing $ docker run -p 8384:8384 -p 22000:22000/tcp -p 22000:22000/udp -p 21027:21027/udp \ -v /wherever/st-sync:/var/syncthing \ --hostname=my-syncthing \ syncthing/syncthing:latest ``` **Docker compose** ```yml --- 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 # Web UI - 22000:22000/tcp # TCP file transfers - 22000:22000/udp # QUIC file transfers - 21027:21027/udp # Receive local discovery broadcasts restart: unless-stopped ``` ## Discovery Note that Docker's default network mode prevents local IP addresses from being discovered, as Syncthing is only able to see the internal IP of the container on the `172.17.0.0/16` subnet. This will result in poor transfer rates if local device addresses are not manually configured. It is therefore advisable to use the [host network mode](https://docs.docker.com/network/host/) instead: **Docker cli** ``` $ docker pull syncthing/syncthing $ docker run --network=host \ -v /wherever/st-sync:/var/syncthing \ syncthing/syncthing:latest ``` **Docker compose** ```yml --- version: "3" services: syncthing: image: syncthing/syncthing container_name: syncthing hostname: my-syncthing environment: - PUID=1000 - PGID=1000 volumes: - /wherever/st-sync:/var/syncthing network_mode: host restart: unless-stopped ``` 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.