Extend NixOS - Revision history

Pigs: /* Quick Implementation */Use current channel for search.nixos.org link

2025-05-07T16:37:17Z

Quick Implementation: Use current channel for search.nixos.org link

← Older revision		Revision as of 16:37, 7 May 2025
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	== Quick Implementation ==		== Quick Implementation ==

	NixOS provides [https://search.nixos.org/options?~~channel=23.05&~~show=systemd a systemd module] with a wide variety of configuration options. A small number of those (which you can check out on [[ NixOS search ]]) allows us to implement this little snippet within our {{ic\|configuration.nix}}:		NixOS provides [https://search.nixos.org/options?show=systemd a systemd module] with a wide variety of configuration options. A small number of those (which you can check out on [[ NixOS search ]]) allows us to implement this little snippet within our {{ic\|configuration.nix}}:

	<syntaxhighlight lang="nix">		<syntaxhighlight lang="nix">

Claes: Change spelling

2024-04-07T08:51:20Z

Change spelling

← Older revision		Revision as of 08:51, 7 April 2024
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	* [https://www.freedesktop.org/software/systemd/man/latest/systemd.html# systemd man pages]		* [https://www.freedesktop.org/software/systemd/man/latest/systemd.html# systemd man pages]
	* NixOS [[ modules ]]		* NixOS [[ modules ]]
	* use [[ NixOS Search ]] and [https://nixos.org/nixos/manual/options.html NixOS Manual: List of Options] to look up more information about specific module options that we use		* use [[NixOS search\|NixOS Search]] and [https://nixos.org/nixos/manual/options.html NixOS Manual: List of Options] to look up more information about specific module options that we use

	= Implementations =		= Implementations =

Samueldr: Fix accidental template transclusion (??)

2024-04-07T01:56:54Z

Fix accidental template transclusion (??)

← Older revision		Revision as of 01:56, 7 April 2024
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	We want to start up an IRC client whenever a user logs into/starts their session.		We want to start up an IRC client whenever a user logs into/starts their session.

	It is possible to find a variety of different ways to do this, but a simple modern approach that fits well within NixOS's ~~{{declarative~~ model}} is to declare a {{ic\|systemd}} unit which initializes the IRC client upon session login by a user.		It is possible to find a variety of different ways to do this, but a simple modern approach that fits well within NixOS's [[Declarative model]] is to declare a {{ic\|systemd}} unit which initializes the IRC client upon session login by a user.

	Assume that our IRC client is {{ic\|irssi}} as the IRC client. We'll run it inside a [https://wiki.archlinux.org/title/GNU_Screen screen] daemon, which apart from allowing us to [https://en.wikipedia.org/wiki/Terminal_multiplexer multiplex] our terminal sessions, also enables the IRC session to continue even after we log out of our shell session.		Assume that our IRC client is {{ic\|irssi}} as the IRC client. We'll run it inside a [https://wiki.archlinux.org/title/GNU_Screen screen] daemon, which apart from allowing us to [https://en.wikipedia.org/wiki/Terminal_multiplexer multiplex] our terminal sessions, also enables the IRC session to continue even after we log out of our shell session.

Samueldr: Fixed casing

2024-04-05T01:12:15Z

Fixed casing

← Older revision		Revision as of 01:12, 5 April 2024
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	= Some helpful links =		= Some helpful links =

	This article assumes some familiarity with [[systemd]], and [[~~NixOs~~ options]]. The following links will be helpful for providing this background:		This article assumes some familiarity with [[systemd]], and [[NixOS options]]. The following links will be helpful for providing this background:

	* General overviews of {{ic\|systemd}}: [https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/system_administrators_guide/chap-managing_services_with_systemd from RedHat], [https://wiki.archlinux.org/title/Systemd the Arch Linux Wiki], [https://www.digitalocean.com/community/tutorials/how-to-use-systemctl-to-manage-systemd-services-and-units tutorial from Digital Ocean]		* General overviews of {{ic\|systemd}}: [https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/system_administrators_guide/chap-managing_services_with_systemd from RedHat], [https://wiki.archlinux.org/title/Systemd the Arch Linux Wiki], [https://www.digitalocean.com/community/tutorials/how-to-use-systemctl-to-manage-systemd-services-and-units tutorial from Digital Ocean]

imported>Bzm3r: Various small fixes to my initial edit.

2023-11-03T23:45:50Z

Various small fixes to my initial edit.

← Older revision		Revision as of 23:45, 3 November 2023
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	Assume that our IRC client is {{ic\|irssi}} as the IRC client. We'll run it inside a [https://wiki.archlinux.org/title/GNU_Screen screen] daemon, which apart from allowing us to [https://en.wikipedia.org/wiki/Terminal_multiplexer multiplex] our terminal sessions, also enables the IRC session to continue even after we log out of our shell session.		Assume that our IRC client is {{ic\|irssi}} as the IRC client. We'll run it inside a [https://wiki.archlinux.org/title/GNU_Screen screen] daemon, which apart from allowing us to [https://en.wikipedia.org/wiki/Terminal_multiplexer multiplex] our terminal sessions, also enables the IRC session to continue even after we log out of our shell session.

			Note that due to the details of systemd, the service we create will run per user, not per session.

			= Some helpful links =

			This article assumes some familiarity with [[systemd]], and [[NixOs options]]. The following links will be helpful for providing this background:

			* General overviews of {{ic\|systemd}}: [https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/system_administrators_guide/chap-managing_services_with_systemd from RedHat], [https://wiki.archlinux.org/title/Systemd the Arch Linux Wiki], [https://www.digitalocean.com/community/tutorials/how-to-use-systemctl-to-manage-systemd-services-and-units tutorial from Digital Ocean]
			* [https://www.freedesktop.org/software/systemd/man/latest/systemd.html# systemd man pages]
			* NixOS [[ modules ]]
			* use [[ NixOS Search ]] and [https://nixos.org/nixos/manual/options.html NixOS Manual: List of Options] to look up more information about specific module options that we use

	= Implementations =		= Implementations =
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	== Quick Implementation ==		== Quick Implementation ==

	NixOS provides [https://search.nixos.org/options?channel=23.05&show=systemd a systemd module] with a wide variety of configuration options. A small number of those (which you can check out on {{NixOS search}}) allows us to implement this little snippet within our {{ic\|configuration.nix}}:		NixOS provides [https://search.nixos.org/options?channel=23.05&show=systemd a systemd module] with a wide variety of configuration options. A small number of those (which you can check out on [[ NixOS search ]]) allows us to implement this little snippet within our {{ic\|configuration.nix}}:

	<syntaxhighlight lang="nix">		<syntaxhighlight lang="nix">
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	# ircSession is the name of the new service we'll be creating		# ircSession is the name of the new service we'll be creating
	systemd.services.ircSession = {		systemd.services.ircSession = {
	#		# this service is "wanted by" (see systemd man pages, or other tutorials) the system
	wantedBy = [ "multi-user.target" ];		# level that allows multiple users to login and interact with the machine non-graphically
			# (see the Red Hat tutorial or Arch Linux Wiki for more information on what each target means)
			# this is the "node" in the systemd dependency graph that will run the service
			wantedBy = [ "multi-user.target" ];
			# systemd service unit declarations involve specifying dependencies and order of execution
			# of systemd nodes; here we are saying that we want our service to start after the network has
			# set up (as our IRC client needs to relay over the network)
	after = [ "network.target" ];		after = [ "network.target" ];
	description = "Start the irc client of username.";		description = "Start the irc client of username.";
	serviceConfig = {		serviceConfig = {
	Type = "~~forking~~";		# see systemd man pages for more information on the various options for "Type": "notify"
			# specifies that this is a service that waits for notification from its predecessor (declared in
			# `after=`) before starting
			Type = "notify";
			# username that systemd will look for; if it exists, it will start a service associated with that user
	User = "username";		User = "username";
	ExecStart = ''${pkgs.screen}/bin/screen -dmS irc ${pkgs.irssi}/bin/irssi'';		# the command to execute when the service starts up
			ExecStart = ''${pkgs.screen}/bin/screen -dmS irc ${pkgs.irssi}/bin/irssi'';
			# and the command to execute
	ExecStop = ''${pkgs.screen}/bin/screen -S irc -X quit'';		ExecStop = ''${pkgs.screen}/bin/screen -S irc -X quit'';
	};		};
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	</syntaxhighlight>		</syntaxhighlight>

	What does this do? ~~The~~ <code>systemd.services.ircSession</code> ~~bit is an~~ option ~~which~~ adds a new ~~system~~ service~~. This option is defined elsewhere in the NixOS configuration files. This is one of many options; you can see a list of all NixOS configuration options in~~ the [https://nixos.org~~/nixos/manual~~/options.~~html NixOS Manual: List of Options~~] ~~(or use https://search~~.~~nixos.org/options to search for options). We add attributes to this option to configure our~~ new service. As you can see, we configure it to start when the network connects, and to execute a shell command.		What does this do?
			* <code>systemd.services.ircSession</code> option adds our new service to the {{ic\|systemd}} module's {{ic\|services}} [https://search.nixos.org/options?channel=unstable&show=systemd.services&from=0&size=50&sort=relevance&type=packages&query=systemd.service attribute set].

			* The comments explain the various configuration steps declaring the definition of the new service. As you can see, we configure it to start when the network connects, and to execute a shell command.

	After rebuilding the NixOS configuration with this file, our IRC session should start when our network connects. The IRC session is started as a child to the screen daemon, which is independent of any user's session and will continue running when we log out. To connect to the IRC session, we SSH into the system, reconnect to the screen session, and choose the IRC window. Here's the command:		After rebuilding the NixOS configuration with this file, our IRC session should start when our network connects. The IRC session is started as a child to the screen daemon, which is independent of any user's session and will continue running when we log out. To connect to the IRC session, we SSH into the system, reconnect to the screen session, and choose the IRC window. Here's the command:

	ssh username@my-server -t screen -d -R irc		{{ ic \| # ssh username@my-server -t screen -d -R irc }}

	== Conditional Implementation ==		== Conditional Implementation ==

imported>Bzm3r at 20:17, 3 November 2023

2023-11-03T20:17:43Z

← Older revision		Revision as of 20:17, 3 November 2023
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	This tutorial shows how to extend a NixOS configuration to include custom [[~~{{ic\|~~systemd}}]] units, by creating a [[~~{{ic\|~~systemd}}]] unit IRC client every time a system session starts. Beginning by adding functionality directly to a {{ic\|configuration.nix}} file, it then shows how to abstract the functionality into a separate NixOS [[module]].		This tutorial shows how to extend a NixOS configuration to include custom [[systemd]] units, by creating a [[systemd]] unit that initializes IRC client every time a system session starts. Beginning by adding functionality directly to a {{ic\|configuration.nix}} file, it then shows how to abstract the functionality into a separate NixOS [[module]].

	= The Problem =		= The Problem =
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	It is possible to find a variety of different ways to do this, but a simple modern approach that fits well within NixOS's {{declarative model}} is to declare a {{ic\|systemd}} unit which initializes the IRC client upon session login by a user.		It is possible to find a variety of different ways to do this, but a simple modern approach that fits well within NixOS's {{declarative model}} is to declare a {{ic\|systemd}} unit which initializes the IRC client upon session login by a user.

	Assume that our IRC client is {{ic\|irssi}} as the IRC client. We'll run it inside a [https://wiki.archlinux.org/title/GNU_Screen ~~{{ic\|~~screen}}] daemon, which apart from allowing us to {{multiplex}} our terminal sessions, also enables the IRC session to continue even after we log out of our shell session.		Assume that our IRC client is {{ic\|irssi}} as the IRC client. We'll run it inside a [https://wiki.archlinux.org/title/GNU_Screen screen] daemon, which apart from allowing us to [https://en.wikipedia.org/wiki/Terminal_multiplexer multiplex] our terminal sessions, also enables the IRC session to continue even after we log out of our shell session.

	= Implementations =		= Implementations =
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	== Quick Implementation ==		== Quick Implementation ==

	NixOS provides [https://search.nixos.org/options?channel=23.05&show=systemd a ~~{{ic\|~~systemd}} module] with a wide variety of configuration options. A small number of those (which you can check out on {{NixOS search}}) allows us to implement this ~~small~~ snippet within our {{ic\|configuration.nix}}:		NixOS provides [https://search.nixos.org/options?channel=23.05&show=systemd a systemd module] with a wide variety of configuration options. A small number of those (which you can check out on {{NixOS search}}) allows us to implement this little snippet within our {{ic\|configuration.nix}}:

	<syntaxhighlight lang="nix">		<syntaxhighlight lang="nix">

imported>Bzm3r: Simplifying language, focusing purpose.

2023-11-03T20:14:50Z

Simplifying language, focusing purpose.

← Older revision		Revision as of 20:14, 3 November 2023
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	This tutorial ~~covers the major points of~~ NixOS configuration~~. In this tutorial~~, ~~we configure NixOS to start an~~ IRC client every time ~~the OS~~ starts. ~~This tutorial will start~~ by adding ~~this~~ functionality to ~~the <code>~~configuration.nix~~</code>~~ file~~. Then~~, ~~this~~ functionality ~~is extracted~~ into a separate ~~file, which~~ NixOS ~~calls a "~~module".		This tutorial shows how to extend a NixOS configuration to include custom [[{{ic\|systemd}}]] units, by creating a [[{{ic\|systemd}}]] unit IRC client every time a system session starts. Beginning by adding functionality directly to a {{ic\|configuration.nix}} file, it then shows how to abstract the functionality into a separate NixOS [[module]].

	= ~~Example: Add a System Service~~ =		= The Problem =

	~~Suppose you~~ want to start an IRC client ~~and connect to your favorite channel every time your NixOS starts. To do this, we will start the IRC client using~~ a ~~shell command. In other distributions, to perform an action on system start, you place the shell command in an init script, which is usually the <code>~~/~~etc/init.d</code> file~~.		We want to start up an IRC client whenever a user logs into/starts their session.

	~~In NixOS, on the other hand~~, ~~all system files are overwritten when the <code>configuration.nix</code> file is updated and the system is rebuilt. How does~~ a NixOS ~~user execute~~ a ~~shell command on system start? In NixOS, all dependencies are clean and organized,~~ which ~~means they are changed in a single place - the <code>configuration.nix</code> and the modules it loads. To change~~ the ~~system's behavior, then, we must add this~~ IRC ~~shell command to this configuration file~~.		It is possible to find a variety of different ways to do this, but a simple modern approach that fits well within NixOS's {{declarative model}} is to declare a {{ic\|systemd}} unit which initializes the IRC client upon session login by a user.

	~~Lets start the~~ IRC ~~session using <code>~~irssi~~</code>~~ as the IRC client. We'll run it inside a ~~<code>~~screen~~</code>~~ daemon, which enables the IRC session to continue even after we log out of our shell session.		Assume that our IRC client is {{ic\|irssi}} as the IRC client. We'll run it inside a [https://wiki.archlinux.org/title/GNU_Screen {{ic\|screen}}] daemon, which apart from allowing us to {{multiplex}} our terminal sessions, also enables the IRC session to continue even after we log out of our shell session.

	= Implementations =		= Implementations =
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	== Quick Implementation ==		== Quick Implementation ==

	~~The simplest way~~ to implement this ~~is to add a simple~~ snippet ~~of code to the <code>/etc/nixos/~~configuration.nix~~</code> file~~:		NixOS provides [https://search.nixos.org/options?channel=23.05&show=systemd a {{ic\|systemd}} module] with a wide variety of configuration options. A small number of those (which you can check out on {{NixOS search}}) allows us to implement this small snippet within our {{ic\|configuration.nix}}:

	<syntaxhighlight lang="nix">		<syntaxhighlight lang="nix">
	~~{pkgs, ...}:~~

	# pkgs is used to fetch screen & irssi.		# pkgs is used to fetch screen & irssi.
			{pkgs, ...}:
	{		{
			# ircSession is the name of the new service we'll be creating
	systemd.services.ircSession = {		systemd.services.ircSession = {
			#
	wantedBy = [ "multi-user.target" ];		wantedBy = [ "multi-user.target" ];
	after = [ "network.target" ];		after = [ "network.target" ];
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	}		}
	</syntaxhighlight>		</syntaxhighlight>

	What does this do? The <code>systemd.services.ircSession</code> bit is an option which adds a new system service. This option is defined elsewhere in the NixOS configuration files. This is one of many options; you can see a list of all NixOS configuration options in the [https://nixos.org/nixos/manual/options.html NixOS Manual: List of Options] (or use https://search.nixos.org/options to search for options). We add attributes to this option to configure our new service. As you can see, we configure it to start when the network connects, and to execute a shell command.		What does this do? The <code>systemd.services.ircSession</code> bit is an option which adds a new system service. This option is defined elsewhere in the NixOS configuration files. This is one of many options; you can see a list of all NixOS configuration options in the [https://nixos.org/nixos/manual/options.html NixOS Manual: List of Options] (or use https://search.nixos.org/options to search for options). We add attributes to this option to configure our new service. As you can see, we configure it to start when the network connects, and to execute a shell command.

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	* [https://web.archive.org/web/20150331124128/http://larrythecow.org/archives/2011-10-11.html System Services on NixOS: larrythecow.org (archived)]		* [https://web.archive.org/web/20150331124128/http://larrythecow.org/archives/2011-10-11.html System Services on NixOS: larrythecow.org (archived)]

			[[Category:systemd]]
	[[Category:Tutorial]]		[[Category:Tutorial]]
	[[Category:NixOS]]		[[Category:NixOS]]

imported>Qm3ster: 1. imports is a config attribute, not to be confused with the import keyword 2. Fixed code to correspond to description

2022-08-31T16:23:07Z

1. imports is a config attribute, not to be confused with the import keyword 2. Fixed code to correspond to description

← Older revision		Revision as of 16:23, 31 August 2022
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	== Modular Configuration ==		== Modular Configuration ==

	To avoid using conditional expressions in our <code>configuration.nix</code> file, we can separate these properties into units and blend them together differently for each host. Nix allows us to do this with the <code>imports</code> ~~keyword~~ (see [https://nixos.org/nixos/manual/index.html#sec-modularity NixOS Manual: Modularity]) to separate each concern into its own file. One way to organize this is to place common properties in the <code>configuration.nix</code> file and move the the IRC-related properties into an <code>irc-client.nix</code> file.		To avoid using conditional expressions in our <code>configuration.nix</code> file, we can separate these properties into units and blend them together differently for each host. Nix allows us to do this with the <code>imports</code> attribute (see [https://nixos.org/nixos/manual/index.html#sec-modularity NixOS Manual: Modularity]) to separate each concern into its own file. One way to organize this is to place common properties in the <code>configuration.nix</code> file and move the the IRC-related properties into an <code>irc-client.nix</code> file.

	If we move the IRC stuff into the <code>irc-client.nix</code> file, we change the <code>configuration.nix</code> file like this:		If we move the IRC stuff into the <code>irc-client.nix</code> file, we change the <code>configuration.nix</code> file like this:
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	];		];

	services.ircClient.enable = ~~true~~;		services.ircClient.enable = config.networking.hostName == "my-server";
	services.ircClient.user = "username";		services.ircClient.user = "username";
	~~config.networking.hostName = "my-server";~~

	# ... usual configuration ...		# ... usual configuration ...

imported>Fricklerhandwerk: Fricklerhandwerk moved page NixOS:extend NixOS to Extend NixOS: do not use category name in title

2022-08-04T08:27:23Z

Fricklerhandwerk moved page NixOS:extend NixOS to Extend NixOS: do not use category name in title

← Older revision		Revision as of 08:27, 4 August 2022
(No difference)

imported>Fricklerhandwerk: add categories: Tutorial, NixOS

2022-08-04T08:27:07Z

add categories: Tutorial, NixOS

← Older revision		Revision as of 08:27, 4 August 2022
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	* [https://web.archive.org/web/20150331124128/http://larrythecow.org/archives/2011-10-11.html System Services on NixOS: larrythecow.org (archived)]		* [https://web.archive.org/web/20150331124128/http://larrythecow.org/archives/2011-10-11.html System Services on NixOS: larrythecow.org (archived)]

			[[Category:Tutorial]]
			[[Category:NixOS]]