launchd: initial support for LaunchAgents by midchildan · Pull Request #2497 · nix-community/home-manager

midchildan · 2021-11-21T17:15:59Z

Description

Add support for macOS LaunchAgents, the equivalent of systemd user services.

Here's a little example of how to use this module:

launchd.agents.syncthing = {
  # whether to enable the LaunchAgent
  enable = true;

  # LaunchAgent configuration translated to the Nix Expression Language
  config = {
    ProgramArguments = [ "${pkgs.syncthing}/bin/syncthing" "-no-browser" "-no-restart" ];
      KeepAlive = {
        Crashed = true;
        SuccessfulExit = false;
      };
      ProcessType = "Background";
  };
};

Checklist

Change is backwards compatible.
Code formatted with ./format.
Code tested through nix-shell --pure tests -A run.all.
Test cases updated/added. See example.
Commit messages are formatted like
```
{component}: {description}

{long description}
```
See CONTRIBUTING for more information and recent commit messages for examples.
If this PR adds a new module
- Added myself as module maintainer. See example.
- Added myself and the module files to .github/CODEOWNERS.

midchildan · 2021-11-21T17:19:40Z

+
+      # NOTE: Launch Agent configurations can't be symlinked from the Nix store
+      # because it needs to be owned by the user running it.
+      home.activation.setupLaunchAgents =


The activation script takes care of starting/restarting/stopping the agents automatically.

midchildan · 2021-11-21T17:24:42Z

+      # NOTE: Launch Agent configurations can't be symlinked from the Nix store
+      # because it needs to be owned by the user running it.


LaunchAgent configuration files are copied into the home directory because Launchd refuses to work with files not owned by the user running it. For safety reasons, the activation script would check if any changes are made to configurations files previously deployed by Home Manager.

midchildan · 2021-11-21T17:33:17Z

+# launchd option type from nix-darwin
+#
+# Original Source:
+# https://github.com/LnL7/nix-darwin/blob/a34dea2/modules/launchd/launchd.nix
+
+# Copyright 2017 Daiderd Jordan
+#
+# Permission is hereby granted, free of charge, to any person obtaining


This file contains the definition for the Launchd option type, the code responsible for translating Nix expressions into LaunchAgent configurations. Since this file comes from the nix-darwin project, I have included the license (MIT) and copyright headers here.

Other files aren't based on outside projects.

berbiche

Thanks for the contribution!

berbiche · 2021-11-23T05:34:32Z

+      assertions = [{
+        assertion = agentPlists != { } -> pkgs.stdenv.isDarwin;
+        message = let names = lib.concatStringsSep ", " (attrNames agentPlists);
+        in "Must use Darwin for modules that require Launchd: " + names;
+      }];


I know the systemd module has the opposite logic, but would it be possible to also add an enable option to check against (with a default value of isDarwin)?

Suggested change

assertions = [{

assertion = agentPlists != { } -> pkgs.stdenv.isDarwin;

message = let names = lib.concatStringsSep ", " (attrNames agentPlists);

in "Must use Darwin for modules that require Launchd: " + names;

}];

assertions = [{

assertion = (cfg.enable && agentPlists != { }) -> isDarwin;

message = let names = lib.concatStringsSep ", " (attrNames agentPlists);

in "Must use Darwin for modules that require Launchd: " + names;

}];

This would make it easier to have services defining both systemd services and launchd agents (until a common backend can be created).

I wonder if the same should be done for systemd as well, or otherwise each systemd service would need to be hidden behind an mkIf for services using both systemd and launchd.

Yeah, we should do the same for systemd services (in a different PR).

berbiche

I missed two things in my initial review.

berbiche · 2021-11-25T02:23:21Z

+let
+  inherit (pkgs.stdenv.hostPlatform) isDarwin;
+  inherit (lib.generators) toPlist;
+  inherit (hm.dag) entryAfter;


This is never used directly.

I've removed this line.

midchildan · 2021-11-25T13:49:03Z

I've rebased against master to fix merge conflicts.

rycee · 2021-12-10T23:38:56Z

+  inherit (lib.generators) toPlist;
+
+  cfg = config.launchd;
+  labelPrefix = "org.nixos.home.";


Maybe something like

Suggested change

labelPrefix = "org.nixos.home.";

labelPrefix = "org.nix-community.home.";

since we're not an official nixos.org project.

I applied your suggestion and changed the tests accordingly. This made me realize there actually is a https://nix-community.org site.

rycee · 2021-12-10T23:46:02Z

+      home.activation.setupLaunchAgents =
+        hm.dag.entryAfter [ "writeBoundary" ] ''
+          setupLaunchAgents() {
+            local oldDir="$(readlink -m "$oldGenPath/LaunchAgents")"


I'm wondering if this may cause problems on the first activation, when $oldGenPath is unset?

Btw, the general recommendation is to declare the variable and assign it in separate statements. I.e. something like

local oldDir oldDir="$(readline …)"

See SC2155 for rationale.

I added more conditional statements to deal with an empty $oldGenPath and also separated variable declarations and assignments.

rycee · 2021-12-10T23:49:30Z

        '';
      }
+
+      {


I think this change is worth mentioning in the release notes as well!

I added an entry in the 22.05 release note.

rycee · 2021-12-10T23:57:38Z

+                continue
+              fi
+              if [[ -f "$dstPath" ]]; then
+                while true; do


Would it be possible to limit this to just a few loops and then, e.g., return with an error message? It makes me a bit nervous to have a potentially infinite loop in an activation script, however unlikely it is to happen 🙂

I set the limit to 10 loops.

rycee · 2021-12-10T23:59:38Z

+                continue
+              fi
+              if ! cmp --quiet "$srcPath" "$dstPath"; then
+                warnEcho "Skipping deletion of '$dstPath', since its contents have diverged"


Nice, I like the "diverged" wording 👍

rycee · 2021-12-11T00:04:27Z

Thanks for the contribution, looks pretty cool! I added a few comments to the best of my ability.

rycee · 2022-02-26T11:36:45Z

Squashed and merged to master now 🙂

midchildan requested a review from rycee as a code owner November 21, 2021 17:15

midchildan commented Nov 21, 2021

View reviewed changes

berbiche requested changes Nov 23, 2021

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berbiche requested changes Nov 25, 2021

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midchildan force-pushed the feat/launchagents branch from 99d5483 to edbec1f Compare November 25, 2021 13:47

rycee reviewed Dec 10, 2021

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midchildan force-pushed the feat/launchagents branch from edbec1f to ab832d9 Compare December 12, 2021 18:53

launchd: initial support for LaunchAgents

c7a13f7

rycee force-pushed the feat/launchagents branch from b892a57 to c7a13f7 Compare February 26, 2022 09:44

rycee mentioned this pull request Feb 26, 2022

launchd description oddities nix-darwin/nix-darwin#441

Closed

rycee merged commit c7a13f7 into nix-community:master Feb 26, 2022

midchildan deleted the feat/launchagents branch February 26, 2022 11:39

midchildan mentioned this pull request Apr 24, 2022

Remove platform check from the systemd module #2915

Merged

7 tasks

		# NOTE: Launch Agent configurations can't be symlinked from the Nix store
		# because it needs to be owned by the user running it.

	labelPrefix = "org.nixos.home.";
	labelPrefix = "org.nix-community.home.";

                       '';
                     }
+                    {

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midchildan commented Nov 21, 2021

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midchildan commented Nov 25, 2021

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rycee commented Dec 11, 2021

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rycee commented Feb 26, 2022

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