nventiveux / docker-syncthing

Docker image for syncthing installation for x86 / arm architectures.

Syncthing Docker image

Syncthing Docker image for RaspberryPi / amd64 systems.

Syncthing replaces proprietary sync and cloud services with something open, trustworthy and decentralized.

See Syncthing website for more.

Tested on following archs:

• x64

Following arch are missing tests:

• arm32v6
• armv7

Available image tags

• nventiveux/syncthing
  • latest, v1.27.9 (Dockerfile)

Usage

Run the container manually (select tag according to the target architecture):

{
mkdir -p "${HOME}/Sync";
docker run \
  -d \
  --name syncthing \
  -p 8384:8384/tcp \
  -p 22000:22000/tcp \
  -p 21027:21027/udp \
  -v syncthing_config:/etc/syncthing \
  -v "${HOME}/Sync":/var/lib/syncthing \
  nventiveux/syncthing:latest;
}

Open the administration website with https://localhost:8384/ and connect using admin / admin.

This will make available for syncing all folders within ~/Sync. You may be interested to adapt environment variables SYNCTHING_USER_UID and SYNCTHING_GROUP_GID to match your user UID / GID at the host (verify with id).

Persisting data

Following paths within the container should be persisted:

• /var/lib/syncthing holds synced content.
• /etc/syncthing holds the syncthing configuration.

Network ports

• Default ports:
  • 21027/udp --> Local discovery (see Known issues)
  • 22000/tcp --> Sync protocol
  • 8384/tcp --> Admin interface

Environment variables

You can configure Syncthing injecting following environment variables:

Variable	Description	Default
SYNCTHING_USER	Name of container user	syncthing
SYNCTHING_USER_UID	Map container user to this UID	1000
SYNCTHING_GROUP	Name of container user primary group	syncthing
SYNCTHING_GROUP_GID	Map container user primary group to this GID	1000
SYNCTHING_ADMIN_USER	Admin username	admin
SYNCTHING_ADMIN_PASSWORD	Admin password	admin

Example to set another password for the admin user:

docker run \
  ...
  -e SYNCTHING_ADMIN_PASSWORD="anotherpassword" \
  ...

Known issues

• Local discovery does not work without --network=host. Need more testing if this can be avoided.

Contribute

Pre-requisites:

• Python >=3.11
• Rye
• make
• Bash >=4
• Git >=2.18

Prepare your environment:

make install

Tweak Dockerfile to your convenience.

Note: if you are upgrading Syncthing to a newer version, also sync the config file version !

Commit changes and submit a Pull Request.

Releasing a new version

Bump the version using:

git switch -c release/next
make release version=<VERSION>
git commit -a -m "feat(core): bump syncthing to <VERSION>"
rye run cz bump --changelog <VERSION>
# Open a pull request

References

• Inspiration taken from tianon/dockerfiles.

docker-syncthing's Issues

Allow to specify user name / UID and group name / GID when running container.

See --user / --group in docker run reference:

• --user: https://docs.docker.com/engine/reference/run/#/user
• --group-add: https://docs.docker.com/engine/reference/run/#/additional-groups

New environment variables:

• SYNCTHING_USER / SYNCTHING_USER_UID
• SYNCTHING_GROUP / SYNCTHING_GROUP_GID

Create a docker-entrypoint.sh which will use such environment variables to create the user and group dynamically at container runtime instead of during image build.

Add an installation script for quick setup using "curl | bash" installer like.

• Ensure Docker Engine is there.
• Pull image
• Install service
• Start

Unique volume name for all instances in systemd service definition !

The syncthing database volume was named syncthing_data for all instances which can cause big
troubles and instance overlap, etc...

Migration steps

In order to change the existing syncthing_data volume to new naming scheme, you need to backup existing syncthing database:

$ sudo systemctl stop docker-syncthing@<INSTANCE>
$ docker run -it --rm -v /tmp/syncthing_backup:/backup -v syncthing_data:/etc/syncthing nventiveux/docker-alpine-rpi tar zcvf /backup/syncthing_db.tar.gz /etc/syncthing

Backup will be available on host in /tmp/syncthing_backup/syncthing_db.tar.gz. Keep it safe.

Destroy the existing volume:

$ docker volume rm syncthing_data

Update systemd service file and start service again to recreate the volume with correct instance name.
Stop the service and restore the database:

$ docker run -it --rm -v /tmp/syncthing_backup:/backup -v syncthing_$USER_data:/etc/syncthing nventiveux/docker-alpine-rpi sh
sh# ( rm -rf /etc/syncthing/* && cd / && tar zxvf /backup/syncthing_db.tar.gz )

Start the service again.

Base from Alpine image instead of debian:jessie

Done in commit 874fd39 but still need build tests !

Able to plan / schedule bandwidth limitations (for poor Internet connections)

We will need augeas package in Alpine image to throttle the bandwidth in /etc/syncthing/config.xml.

Add more LABELS

• Description
• License