11.3.1 Essential Home Services

There are a few essential home services defined in (gnu services), they are mostly for internal use and are required to build a home environment, but some of them will be useful for the end user.

Scheme Variable: home-environment-variables-service-type

The service of this type will be instantiated by every home environment automatically by default, there is no need to define it, but someone may want to extend it with a list of pairs to set some environment variables.

(list ("ENV_VAR1" . "value1")
      ("ENV_VAR2" . "value2"))

The easiest way to extend a service type, without defining new service type is to use the simple-service helper from (gnu services).

(simple-service 'some-useful-env-vars-service
		home-environment-variables-service-type
		`(("LESSHISTFILE" . "$XDG_CACHE_HOME/.lesshst")
                  ("SHELL" . ,(file-append zsh "/bin/zsh"))
                  ("USELESS_VAR" . #f)
                  ("_JAVA_AWT_WM_NONREPARENTING" . #t)))

If you include such a service in you home environment definition, it will add the following content to the setup-environment script (which is expected to be sourced by the login shell):

export LESSHISTFILE=$XDG_CACHE_HOME/.lesshst
export SHELL=/gnu/store/2hsg15n644f0glrcbkb1kqknmmqdar03-zsh-5.8/bin/zsh
export _JAVA_AWT_WM_NONREPARENTING

Note: Make sure that module (gnu packages shells) is imported with use-modules or any other way, this namespace contains the definition of the zsh packages, which is used in the example above.

The association list (see Association Lists in The GNU Guile Reference manual) is a data structure containing key-value pairs, for home-environment-variables-service-type the key is always a string, the value can be a string, string-valued gexp (see G-Expressions), file-like object (see file-like object) or boolean. For gexps, the variable will be set to the value of the gexp; for file-like objects, it will be set to the path of the file in the store (see The Store); for #t, it will export the variable without any value; and for #f, it will omit variable.

Scheme Variable: home-profile-service-type

The service of this type will be instantiated by every home environment automatically, there is no need to define it, but you may want to extend it with a list of packages if you want to install additional packages into your profile. Other services, which need to make some programs available to the user will also extend this service type.

The extension value is just a list of packages:

(list htop vim emacs)

The same approach as simple-service (see simple-service) for home-environment-variables-service-type can be used here, too. Make sure that modules containing the specified packages are imported with use-modules. To find a package or information about its module use guix search (see Invoking guix package). Alternatively, specification->package can be used to get the package record from string without importing related module.

There are few more essential services, but users are not expected to extend them.

Scheme Variable: home-service-type

The root of home services DAG, it generates a folder, which later will be symlinked to ~/.guix-home, it contains configurations, profile with binaries and libraries, and some necessary scripts to glue things together.

Scheme Variable: home-run-on-first-login-service-type

The service of this type generates a Guile script, which is expected to be executed by the login shell. It is only executed if the special flag file inside XDG_RUNTIME_DIR hasn’t been created, this prevents redundant executions of the script if multiple login shells are spawned.

It can be extended with a gexp. However, to autostart an application, users should not use this service, in most cases it’s better to extend home-shepherd-service-type with a Shepherd service (see Shepherd Services), or extend the shell’s startup file with the required command using the appropriate service type.

Scheme Variable: home-activation-service-type

The service of this type generates a guile script, which runs on every guix home reconfigure invocation or any other action, which leads to the activation of the home environment.