On macOS, a Launch Agent is a system daemon that runs in the background and performs various tasks or services for the user. Having recently installed ollama, I’ve been playing around with various local models. One annoyance about having installed ollama using Nix via nix-darwin, is that I need to run ollama serve in a terminal session or else I would see something like this:

❯ ollama list
Error: could not connect to ollama app, is it running?

After some code searching, I discovered a method to create a Launch Agent plist for my user using nix-darwin. This allows ollama serve to run automatically in the background for my user. Here’s what it looks like:

  description = "DCMBP Darwin system flake";

  inputs = {

  outputs = inputs@{ self, nix-darwin, nixpkgs, home-manager, ... }:
  configuration = { pkgs, ... }: {
    environment.systemPackages = with pkgs; [ ollama ];


      launchd = {
        user = {
          agents = {
            ollama-serve = {
              command = "${pkgs.ollama}/bin/ollama serve";
              serviceConfig = {
                KeepAlive = true;
                RunAtLoad = true;
                StandardOutPath = "/tmp/ollama_danielcorin.out.log";
                StandardErrorPath = "/tmp/ollama_danielcorin.err.log";

This configuration creates a plist file at /Users/danielcorin/Library/LaunchAgents that looks like this:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
		<string>exec /nix/store/nql9lrcn99m34icj20ydm5jjw33pcpcy-ollama-0.1.27/bin/ollama serve</string>

Now, when I create a new shell session and run ollama list, it just works. Here is the code diff where I added this in my nix config.