Adding System Services to NixOS

Name: add-system-service
Rating: 88
Author: AltanS

This skill covers adding system-level services (Docker, databases, etc.) to the NixOS configuration.

Service Module Location

code

system/services/<service-name>.nix

Standard Service Pattern

nix

# system/services/<service-name>.nix
{ config, pkgs, user, ... }: {
  # Enable the service
  services.<service-name>.enable = true;

  # Add user to service group if needed
  users.users.${user}.extraGroups = [ "<service-group>" ];

  # Install related tools
  environment.systemPackages = with pkgs; [
    <related-package>
  ];
}

Docker Example

nix

# system/services/docker.nix
{ pkgs, user, ... }: {
  virtualisation.docker = {
    enable = true;
    enableOnBoot = true;
  };
  users.users.${user}.extraGroups = [ "docker" ];
  environment.systemPackages = [ pkgs.docker-compose ];
}

PostgreSQL Example

nix

# system/services/postgresql.nix
{ pkgs, ... }: {
  services.postgresql = {
    enable = true;
    package = pkgs.postgresql_15;
    enableTCPIP = true;
    authentication = ''
      local all all trust
      host all all 127.0.0.1/32 trust
    '';
  };
}

Integration Steps

•
Create the service module in system/services/
•
Import in host config:

nix

# hosts/<hostname>/default.nix
imports = [
  ./hardware.nix
  ../../system/profiles/desktop.nix
  ../../system/services/<service-name>.nix  # Add this
];

•Rebuild and switch:

bash

sudo nixos-rebuild switch --flake .#<hostname>

•For VM development, use dev-sync:

bash

./scripts/dev-sync rebuild

Common Services

Service	NixOS Option	Group
Docker	`virtualisation.docker`	`docker`
Podman	`virtualisation.podman`	-
PostgreSQL	`services.postgresql`	-
MySQL	`services.mysql`	-
Redis	`services.redis`	-
nginx	`services.nginx`	-

Verification

After rebuild, verify service is running:

bash

systemctl status <service-name>

# For Docker
docker run hello-world

Important Notes

•The user variable comes from flake.nix extraSpecialArgs
•Services in system/services/ are opt-in per host
•Don't add services directly to system/base/ (those apply to all hosts)