# Introduction

Taskchampion Sync-Server is an implementation of the TaskChampion sync protocol server. It supports synchronizing Taskwarrior tasks between multiple systems.

The project provides both pre-built images for common use-cases (see usage) and Rust libraries that can be used to build more sophisticated applications (integration).

# Usage

## Running the Server

The server is a simple binary that serves HTTP requests on a TCP port. The server does not implement TLS; for public deployments, the recommendation is to use a reverse proxy such as Nginx, haproxy, or Apache httpd.

### Using Docker-Compose

Every release of the server generates a Docker image in `ghcr.io/gothenburgbitfactory/taskchampion-sync-server`. The tags include `latest` for the latest release, and both minor and patch versions, e.g., `0.5` and `0.5.1`.

The `docker-compose.yml` file in this repository is sufficient to run taskchampion-sync-server, including setting up TLS certificates using Lets Encrypt, thanks to Caddy.

You will need a server with ports 80 and 443 open to the Internet and with a fixed, publicly-resolvable hostname. These ports must be available both to your Taskwarrior clients and to the Lets Encrypt servers.

On that server, download `docker-compose.yml` from the link above (it is pinned to the latest release) into the current directory. Then run

    TASKCHAMPION_SYNC_SERVER_HOSTNAME=taskwarrior.example.com \
    TASKCHAMPION_SYNC_SERVER_CLIENT_ID=your-client-id \
    docker compose up

The `TASKCHAMPION_SYNC_SERVER_CLIENT_ID` limits the server to the given client ID; omit it to allow all client IDs.

It can take a few minutes to obtain the certificate; the caddy container will log a message "certificate obtained successfully" when this is complete, or error messages if the process fails. Once this process is complete, configure your `.taskrc`'s to point to the server:

    sync.server.url=https://taskwarrior.example.com
    sync.server.client_id=your-client-id
    sync.encryption_secret=your-encryption-secret

The docker-compose images store data in a docker volume named `taskchampion-sync-server_data`. This volume contains all of the task data, as well as the TLS certificate information. It will persist over restarts, in a typical Docker installation. The docker containers will start automatically on system startup. See the docker-compose documentation for more information.

### Running the Binary

The server is configured with command-line options. See `taskchampion-sync-server --help` for full details.

The `--listen` option specifies the interface and port the server listens on. It must contain an IP-Address or a DNS name and a port number. This option is mandatory, but can be repeated to specify multiple interfaces or ports. This value can be specified in environment variable `LISTEN`, as a comma-separated list of values.

The `--data-dir` option specifies where the server should store its data. This value can be specified in the environment variable `DATA_DIR`.

By default, the server will allow all clients and create them in the database on first contact. There are two ways to limit the clients the server will interact with:

- To limit the accepted client IDs, specify them in the environment variable `CLIENT_ID`, as a comma-separated list of UUIDs. Client IDs can be specified with `--allow-client-id`, but this should not be used on shared systems, as command line arguments are visible to all users on the system. This convenient option is suitable for personal and small-scale deployments.

- To disable the automatic creation of clients, use the `--no-create-clients` flag or the `CREATE_CLIENTS=false` environment variable. You are now responsible for creating clients in the database manually, so this option is more suitable for large scale deployments.

The server only logs errors by default. To add additional logging output, set environment variable `RUST_LOG` to `info` to get a log message for every request, or to `debug` to get more verbose debugging output.

# Integration

TBD (pending Postgres support)