Quassel

From the homepage:

Quassel IRC is a modern, cross-platform, distributed IRC client, meaning that one (or multiple) client(s) can attach to and detach from a central core -- much like the popular combination of screen and a text-based IRC client such as WeeChat, but graphical. In addition to this unique feature, we aim to bring a pleasurable, comfortable chatting experience to all major platforms (including Linux®, Windows®, and MacOS X® as well as Android smartphones), making communication with your peers not only convenient, but also ubiquitous available.

Client

Previously, multiple builds of Quassel clients were provided in Nixpkgs. It is not the case anymore.

The client is quasselClient.

Server

To enable the Quassel server (variously referred to as the Quassel daemon or Quassel Core), add

services.quassel.enable = true;

to your NixOS configuration. By default, the server only accepts connections from the local machine; set

services.quassel.interfaces = [ "0.0.0.0" ];
networking.firewall.allowedTCPPorts = [ 4242 ];

to accept external connections.

Tip

In order to affect your system by your nix-language-specific changes you have to evaluate it, run (as root):

# nixos-rebuild switch

The first time you connect to the new server, a wizard will guide you through the remaining configuration steps. Before connecting to the new server, you may wish to optionally configure SSL or PostgreSQL.

SSL

The Quassel server can use SSL if a certificate is provided. Install openssl (using nix-env or by adding it to environment.systemPackages) and run

sudo -u quassel mkdir -p /home/quassel/.config/quassel-irc.org
sudo -u quassel openssl req -x509 -nodes -days 365 -newkey rsa:4096 -keyout /home/quassel/.config/quassel-irc.org/quasselCert.pem -out /home/quassel/.config/quassel-irc.org/quasselCert.pem

You will be prompted for some details about the certificate. If quassel.service was running, restart it by running:

sudo systemctl restart quassel.service

PostgreSQL

By default, Quassel uses an SQLite database, but it can be configured to use PostgreSQL for better performance. (If you aren't sure which database backend you want to use, stay with SQLite because it is always possible to switch to PostgreSQL later.)

Start by enabling the PostgreSQL service in your NixOS configuration:

 /* Enable the PostgreSQL service */
 services.postgresql = {
   enable = true;
   package = pkgs.postgresql94;
 };
 
 /* Only start Quassel after PostgreSQL has started */
 systemd.services.quassel.after = [ "postgresql.service" ];
 
 /* Make the quasselcore command available in the shell */
 environment.systemPackages = [ pkgs.quasselDaemon_qt5 ];

Activate this configuration with nixos-rebuild switch. Create a PostgreSQL role (user) for Quassel:

sudo createuser -A -D -P -E -W quassel

You will be prompted for a password; you will also need to provide the password to Quassel, so don't forget it! Create a PostgreSQL database for Quassel:

sudo createdb -O quassel -E UTF8 quassel

If you have never connected to this Quassel server before, you can connect now and select the PostgreSQL backend when prompted. You will need to provide the PostgreSQL username (quassel) and password you created above.

If you are switching from the SQLite backend to the PostgreSQL backend, you will need to migrate the existing data. Stop the Quassel server with

sudo systemctl stop quassel.service

Start the migration with

sudo -u quassel quasselcore --configdir=/home/quassel/.config/quassel-irc.org --select-backend=PostgreSQL

You will need to provide the PostgreSQL username (quassel) and password you created above. When this is finished, restart the Quassel server:

sudo systemctl start quassel.service