(address . guix-patches@gnu.org)
87leh9d6o5.fsf@librem.one
From ed111e39aa2d188a146e73251aff63156698bb54 Mon Sep 17 00:00:00 2001
From: Mitchell Schmeisser <mitchellschmeisser@librem.one>
Date: Sat, 27 May 2023 13:22:32 -0400
Subject: [PATCH] home: add gnu/home/services/dict.scm and
home-dicod-service-type
* gnu/home/services/dict.scm: Add home-dicod-service-type
---
gnu/home/services/dict.scm | 84 ++++++++++++++++++++++++++++++++++++++
1 file changed, 84 insertions(+)
create mode 100644 gnu/home/services/dict.scm
Toggle diff (92 lines)
diff --git a/gnu/home/services/dict.scm b/gnu/home/services/dict.scm
new file mode 100644
index 0000000000..2d745baa5d
--- /dev/null
+++ b/gnu/home/services/dict.scm
@@ -0,0 +1,84 @@
+(define-module (gnu home services dict)
+ #:use-module (srfi srfi-1)
+ #:use-module (guix gexp)
+ #:use-module (guix least-authority)
+ #:use-module (gnu build linux-container)
+ #:use-module (gnu home services)
+ #:use-module (gnu home services shepherd)
+ #:use-module (gnu packages dictionaries)
+ #:use-module (gnu services dict)
+ #:use-module (gnu system file-systems)
+
+ #:export (%home-dicod-database:gcide
+ %home-dicod-configuration
+ home-dicod-service-type))
+
+(define dico-run-time-dir "/tmp/dico")
+
+(define %home-dicod-database:gcide
+ (dicod-database
+ (name "gcide")
+ (handler "gcide")
+ (options (list #~(string-append "dbdir=" #$gcide "/share/gcide")
+ #~(string-append "idxdir=" #$dico-run-time-dir)))))
+
+(define %home-dicod-configuration
+ (dicod-configuration
+ (databases (list %home-dicod-database:gcide))))
+
+(define %home-dicod-activation
+ #~(begin
+ (use-modules (guix build utils))
+ (mkdir-p #$dico-run-time-dir)))
+
+(define (home-dicod-shepherd-service config)
+ (let* ((dicod.conf ((@@ (gnu services dict) dicod-configuration-file) config))
+ (interfaces ((@@ (gnu services dict) dicod-configuration-interfaces) config))
+ (dicod (least-authority-wrapper
+ (file-append
+ ((@@ (gnu services dict) dicod-configuration-dico) config) "/bin/dicod")
+ #:name "dicod"
+ #:mappings (list (file-system-mapping
+ (source dico-run-time-dir)
+ (target source)
+ (writable? #t))
+ (file-system-mapping
+ (source "/dev/log")
+ (target source))
+ (file-system-mapping
+ (source dicod.conf)
+ (target source)))
+ #:namespaces (delq 'net %namespaces))))
+ (list (shepherd-service
+ (provision '(dicod))
+ (documentation "Run the dicod daemon.")
+ (start #~(if (and (defined? 'make-inetd-constructor)
+ #$(= 1 (length interfaces))) ;XXX
+ (make-inetd-constructor
+ (list #$dicod "--inetd" "--foreground"
+ (string-append "--config=" #$dicod.conf))
+ (addrinfo:addr
+ (car (getaddrinfo #$(first interfaces) "dict")))
+ #:service-name-stem "dicod")
+ (make-forkexec-constructor
+ (list #$dicod "--foreground"
+ (string-append "--config=" #$dicod.conf)))))
+ (stop #~(if (and (defined? 'make-inetd-destructor)
+ #$(= 1 (length interfaces))) ;XXX
+ (make-inetd-destructor)
+ (make-kill-destructor)))
+ (actions (list (shepherd-configuration-action dicod.conf)))))))
+
+(define home-dicod-service-type
+ (service-type
+ (name 'home-dicod)
+ (extensions (list (service-extension home-shepherd-service-type
+ home-dicod-shepherd-service)
+ (service-extension home-activation-service-type
+ (const %home-dicod-activation))))
+ (default-value %home-dicod-configuration)
+ (description
+ "Run @command{dicod}, the dictionary server of
+@uref{https://www.gnu.org/software/dico, GNU Dico}. @command{dicod}
+implements the standard DICT protocol supported by clients such as
+@command{dico} and GNOME Dictionary as a user.")))
--
2.39.1
Here is a patch to add dicod service type to Guix Home,
and here are some things I wrote about the process.
---------------------------------
#+title: Extending Guix Home
#+author: Mitchell Schmeisser <mitchellschmeisser@librem.one>
I recently learned of a new [[https://www.masteringemacs.org/article/wordsmithing-in-emacs][Emacsfeature]] ~M-x dictionary~ which
allows you to connect to a dictionary server using a special protocol.
Out of the box Emacs can reach out to places like [[https://dictionary.com][dictionary.com]]
to look up the definition of words.
This is convenient, but it is a [[https://www.gnu.org/philosophy/who-does-that-server-really-serve.en.html][Serviceas a Software Substitute]].
There is no reason why I cannot run my own dictionary server and
protect my privacy. After all, you never know when the NSA will try
to change the definitions of words to make you look foolish.
It is very easy to run one of these servers in a freedom respecting way,
simply get your hands on a copy of GNU Dico and your dictionary of choice
and run ~dicod~. Most people like to run ~dicod~ as a service which is
managed by the init system.
To my dismay every tutorial and blog post required the user to
use ~sudo~ to install programs and modify the init system.
This is less than desirable.
A wonderful, often under-rated, feature of GNU Guix is /unprivileged/
package management. An even more under-rated feature of GNU Guix
is /unprivileged/ service management provided by [[https://guix.gnu.org/en/blog/2022/keeping-ones-home-tidy/][GuixHome]].
* Guix Home Services
Guix Home allows you to extend the declarative Guix model to your home
environment.
You can install packages and dot files transactionally, making migration
to a new machine painless and consistent.
Unfortunately, at the time of writing there are very few Guix Home services
and most of them simply generate dot files for this or that shell.
Or are there?
* System Services are Home Services
GNU Guix has a ~dico-service-type~ which is very easy to use.
Unfortunately this service type requires system-wide modifications and
requires root. It is also out of reach for people running Guix on a
foreign distribution where ~guix system reconfigure~ is not an option.
Below is the definition of the ~dicod-service-type~ designed for the
Guix System.
#+BEGIN_SRC scheme
;; from gnu/services/dict.scm
(define dicod-service-type
(service-type
(name 'dict)
(extensions
(list (service-extension account-service-type
(const %dicod-accounts))
(service-extension activation-service-type
(const %dicod-activation))
(service-extension shepherd-root-service-type
dicod-shepherd-service)))
(default-value (dicod-configuration))
(description
"Run @command{dicod}, the dictionary server of
@uref{https://www.gnu.org/software/dico,GNU Dico}. @command{dicod}
implements the standard DICT protocol supported by clients such as
@command{dico} and GNOME Dictionary.")))
#+END_SRC
Here is the definition of the ~home-dicod-service-type~.
The only difference between them is for Guix Home we want to run
all processes as the user and cannot create new accounts.
#+BEGIN_SRC scheme
(define home-dicod-service-type
(service-type
(name 'home-dict)
(extensions (list (service-extension home-shepherd-service-type
home-dicod-shepherd-service)
(service-extension home-activation-service-type
(const %home-dicod-activation))))
(default-value %home-dicod-configuration)
(description
"Run @command{dicod}, the dictionary server of
@uref{https://www.gnu.org/software/dico,GNU Dico}. @command{dicod}
implements the standard DICT protocol supported by clients such as
@command{dico} and GNOME Dictionary as a user.")))
#+END_SRC
In general, this is the only difference between a Home Service and a System Service.
System services will generally insist on an account specifically for running a process
and take some steps to create an environment where that account has just enough permissions
to do the job. Home services all run as the user and so the the user
needs to have enough permissions to do the job. =/var/run= becomes =$XDG_RUNTIME_DIR= or
=/run/user/$(uid)/=.
* Unprivileged, Containerized, dictionary server
Using the code below I can finally look up the definitions of words in
complete, unprivileged, freedom! This service spawns a ~dicod~ server
isolated from the system using ~least-authority-wrapper~. It shares
the network namespace and can see it's run-time directory and
read-only configuration file and that is it.
This is nice, but could it be nicer?
#+BEGIN_SRC scheme
;; A new database is defined which places the idxdir argument
;; in a place writable by the user.
;; /tmp was chosen over XDG_RUNTIME_DIR or /run/user/
;; because I do not know when this is evaluated.
;; guix pull time or guix home reconfigure time.
;; I think these are the same in most cases but maybe they're not?
(define runtime-dir "/tmp/dico")
(define %home-dicod-database:gcide
(dicod-database
(name "gcide")
(handler "gcide")
(options (list #~(string-append "dbdir=" #$gcide "/share/gcide")
#~(string-append "idxdir=" #$runtime-dir)))))
(define %home-dicod-configuration
(dicod-configuration
(databases (list %home-dicod-database:gcide))))
(define %home-dicod-activation
#~(begin
(use-modules (guix build utils))
(mkdir-p #$runtime-dir)))
(define (home-dicod-shepherd-service config)
(let* ((dicod.conf ((@@ (gnu services dict) dicod-configuration-file) config))
(interfaces ((@@ (gnu services dict) dicod-configuration-interfaces) config))
(dicod (least-authority-wrapper
(file-append
((@@ (gnu services dict) dicod-configuration-dico) config) "/bin/dicod")
#:name "dicod"
#:mappings (list (file-system-mapping
(source runtime-dir)
(target source)
(writable? #t))
(file-system-mapping
(source "/dev/log")
(target source))
(file-system-mapping
(source dicod.conf)
(target source)))
#:namespaces (delq 'net %namespaces))))
(list (shepherd-service
(provision '(dicod))
(documentation "Run the dicod daemon.")
(start #~(if (and (defined? 'make-inetd-constructor)
#$(= 1 (length interfaces))) ;XXX
(make-inetd-constructor
(list #$dicod "--inetd" "--foreground"
(string-append "--config=" #$dicod.conf))
(addrinfo:addr
(car (getaddrinfo #$(first interfaces) "dict")))
#:service-name-stem "dicod")
(make-forkexec-constructor
(list #$dicod "--foreground"
(string-append "--config=" #$dicod.conf)))))
(stop #~(if (and (defined? 'make-inetd-destructor)
#$(= 1 (length interfaces))) ;XXX
(make-inetd-destructor)
(make-kill-destructor)))
(actions (list (shepherd-configuration-action dicod.conf)))))))
#+END_SRC
* Is =gnu/home/services= an Anti-Pattern?
The code above is almost identical to the code located in
=gnu/services/dict.scm=. The only difference, as a mentioned, is the
account information. With this in mind, does it make sense to define
Home Services along side their system counter parts in =gnu/services=?
I believe many services in =gnu/services= can run from Guix Home with
only minor modifications.