# Syncthing

[Syncthing](https://syncthing.net/) is a **continuous file synchronization** program which synchronizes files between two or more computers in real time, safely protected from prying eyes.


## Dependencies

This service requires the following other services:

- a [Traefik](traefik.md) reverse-proxy server


## Configuration

To enable this service, add the following configuration to your `vars.yml` file and re-run the [installation](../installing.md) process:

```yaml
########################################################################
#                                                                      #
# syncthing                                                            #
#                                                                      #
########################################################################

syncthing_enabled: true

syncthing_hostname: mash.example.com
syncthing_path_prefix: /syncthing

# By default, the data directory is created at (`/mash/syncthing/data`), as defined below.
# If you'd like to put it elsewhere on the host, uncomment and edit the line below.
#
# Regardless of the location of the data directory on the host,
# it will be mounted into the Syncthing container at `/data`.
# syncthing_data_path: "{{ syncthing_base_path }}/data"

# To mount additional data directories, use `syncthing_container_additional_volumes`.

# Secure with HTTP Basic Auth (at the Traefik level)
syncthing_basicauth_enabled: true

# Syncthing is NOT a multi-user system.
# Whichever user you authenticate with later, you would get to the same shared system.
syncthing_basicauth_credentials:
  - username: someone
    password: secret-password
  - username: another
    password: more-secret-password

########################################################################
#                                                                      #
# /syncthing                                                           #
#                                                                      #
########################################################################
```

### URL

In the example configuration above, we configure the service to be hosted at `https://mash.example.com/syncthing`.

You can remove the `syncthing_path_prefix` variable definition, to make it default to `/`, so that the service is served at `https://mash.example.com/`.

### Authentication

You can log in with **any** of the Basic Auth credentials defined in `syncthing_basicauth_credentials`. Syncthing is **not a multi-user system**, so whichever user you authenticate with, you'd ultimately end up looking at the same shared system.

Authentication is **done at the reverse-proxy level** (Traefik), so upon logging in, Syncthing will show you scary warnings about **no GUI password being set**. You should ignore these warnings.

You can hide the warning permanently by going to **Actions** -> **Advanced** -> **GUI** section -> checking the **Insecure Admin Access** checkbox.

### Networking

By default, the following ports will be exposed by the container on **all network interfaces**:

- `22000` over **TCP**, controlled by `syncthing_container_sync_tcp_bind_port` - used for TCP based sync protocol traffic
- `22000` over **UDP**, controlled by `syncthing_container_sync_udp_bind_port` - used for QUIC based sync protocol traffic
- `21027` over **UDP**, controlled by `syncthing_container_local_discovery_udp_bind_port` - used for discovery broadcasts on IPv4 and multicasts on IPv6

Docker automatically opens these ports in the server's firewall, so you **likely don't need to do anything**. If you use another firewall in front of the server, you may need to adjust it.

To learn more, see the upstream [Firewall documentation](https://docs.syncthing.net/users/firewall.html).

### Configuration & Data

The Syncthing configuration (stored in `syncthing_config_path` on the host) is mounted to the `/var/syncthing` directory in the container.
By default, Syncthing will create a default `Sync` directory underneath. We advise that you **don't use this** `Sync` directory and use the data directory (discussed below).

As mentioned above, the **data directory** (stored in `syncthing_data_path` on the host) is mounted to the `/data` directory in the container. We advise that you put data files underneath `/data` when you start using Syncthing.

If you'd like to **mount additional directories** into the container, look into the `syncthing_container_additional_volumes` variable part of the [`ansible-role-syncthing` role](https://github.com/mother-of-all-self-hosting/ansible-role-syncthing)'s [`defaults/main.yml` file](https://github.com/mother-of-all-self-hosting/ansible-role-syncthing/blob/main/defaults/main.yml).


## Usage

After installation, you can go to the Syncthing URL, as defined in `syncthing_hostname` and `syncthing_path_prefix`.

As mentioned in [Configuration & Data](#configuration--data) above, you should:

- get rid of the `Default Folder` directory that was automatically created in `/var/syncthing/Sync`
- change the default data directory, by going to **Actions** -> **Settings** -> **General** tab -> **Edit Folder Defaults** and changing **Folder Path** to `/data`

As mentioned in [Authentication](#authentication) above, you'd probably wish to permanently disable the "no GUI password set" security warnings as described there.