services: Introduce extensible services.

This patch rewrites GuixSD services to make them extensible.

* gnu-system.am (GNU_SYSTEM_MODULES): Add gnu/services/dbus.scm.
* gnu/services.scm (<service>): Replace with new record type.
  (<service-extension>, <service-type>): New record types.
  (write-service-type, compute-boot-script, second-argument): New
  procedures.
  (%boot-service, boot-service-type): New variables.
  (file-union, directory-union, modprobe-wrapper,
  activation-service->script, activation-script,
  gexps->activation-gexp): New procedures.
  (activation-service-type, %activation-service): New variables.
  (etc-directory, files->etc-directory, etc-service): New procedures.
  (etc-service-type, setuid-program-service, firmware-service-type): New
  variables.
  (firmware->activation-gexp): New procedure.
  (&service-error, &missing-target-service-error,
  &ambiguous-target-service-error): New condition types.
  (service-back-edges, fold-services): New procedures.
* gnu/services/avahi.scm (<avahi-configuration>): New record type.
  (configuration-file): Replace keyword parameters with a single
  'config' parameter.
  (%avahi-accounts, %avahi-activation, avahi-service-type): New
  variables.
  (avahi-dmd-service): New procedure.
  (avahi-service): Rewrite using 'service' and 'avahi-configuration'.
* gnu/services/base.scm (%root-file-system-dmd-service,
  root-file-system-service-type): New variables.
  (root-file-system-service): Use them.
  (file-system->dmd-service-name): New procedure.
  (file-system-service-type): New variable.
  (file-system-service): Use it.  Replace keyword parameters with a
  single 'file-system' object.
  (user-unmount-service-type): New variable.
  (user-unmount-service): Use it.
  (user-processes-service-type): New variable.
  (user-processes-service): Use it.
  (host-name-service-type): New variable.
  (host-name-service): Use it.
  (console-keymap-service-type): New variable.
  (console-keymap-service): Use it.
  (console-font-service-type): New variable.
  (console-font-service): Use it.
  (mingetty-pam-service, mingetty-dmd-service): New procedures.
  (mingetty-service-type): New variable.
  (mingetty-service): Use it.
  (nscd-dmd-service): New procedure.
  (nscd-activation, nscd-service-type): New variables.
  (nscd-service): Use the latter.
  (syslog-service-type): New variable.
  (syslog-service): Use it.
  (<guix-configuration>): New record type.
  (%default-guix-configuration): New variable.
  (guix-dmd-service, guix-accounts, guix-activation): New procedures.
  (guix-service-type): New variable.
  (guix-service): Replace list of keyword parameters with a single
  'config' parameter.  Rewrite using 'service'.
  (<udev-configuration>): New record type.
  (udev-dmd-service): New procedure.
  (udev-service-type): New variable.
  (udev-service): Use it.
  (device-mapping-service-type): New variable.
  (device-mapping-service): Use it.
  (swap-service-type): New variable.
  (swap-service): Use it.
* gnu/services/databases.scm (<postgresql-configuration>): New record
  type.
  (%postgresql-accounts, postgresql-activation): New variables.
  (postgresql-dmd-service): New procedure.
  (postgresql-service): Rewrite using 'service' and
  'postgresql-configuration'.
* gnu/services/dbus.scm: New file.
* gnu/services/desktop.scm (dbus-configuration-directory, dbus-service):
  Remove.
  (wrapped-dbus-service): New procedure.
  (<upower-configuration>): New record type.
  (upower-configuration-file): Replace keyword parameters with single
  <upower-configuration> parameter.
  (%upower-accounts, %upower-activation): New variables.
  (upower-dbus-service, upower-dmd-service): New procedures.
  (upower-service-type): New variable.
  (upower-service): Rewrite using 'service' and 'upower-configuration'.
  (%colord-activation, %colord-accounts): New variables.
  (colord-dmd-service): New procedure.
  (colord-service-type): New variable.
  (colord-service): Rewrite using 'service'.
  (<geoclue-configuration>): New record type.
  (geoclue-configuration-file): Replace keyword parameters with a single
  'config' parameter.
  (geoclue-dbus-service, geoclue-dmd-service): New procedures.
  (%geoclue-accounts, geoclue-service-type): New variables.
  (geoclue-service): Rewrite using 'service' and
  'geoclue-configuration'.
  (%polkit-accounts, %polkit-pam-services, polkit-service-type): New
  variables.
  (polkit-dmd-service): New procedure.
  (polkit-service): Rewrite using 'service'.
  (<elogind-configuration>)[elogind]: New field.
  (elogind-dmd-service): New procedure.
  (elogind-service-type): New variable.
  (elogind-service): Rewrite using 'service'.
  (%desktop-services): Remove argument to 'dbus-service'.  Remove 'map'
  over %BASE-SERVICES.
* gnu/services/dmd.scm (dmd-boot-gexp): New procedure.
  (dmd-root-service-type, %dmd-root-service): New variables.
  (dmd-service-type): New macro.
  (<dmd-service>): New record type.
* gnu/services/lirc.scm (<lirc-configuration>): New record type.
  (%lirc-activation): New variable.
  (lirc-dmd-service): New procedure.
  (lirc-service-type): New variable.
  (lirc-service): Rewrite using 'service' and 'lirc-configuration'.
* gnu/services/networking.scm (<static-networking>): New record type.
  (static-networking-service-type): New variable.
  (static-networking-service): Rewrite using 'service' and
  'static-networking'.
  (dhcp-client-service-type): New variable.
  (dhcp-client-service): Rewrite using 'service'.
  (<ntp-configuration>): New record type.
  (ntp-dmd-service): New procedure.
  (ntp-service-type): New variable.
  (ntp-service): New procedure.
  (%tor-accounts, tor-service-type): New variable.
  (tor-dmd-service): New procedure.
  (tor-service): Rewrite using 'service'.
  (<bitlbee-configuration>): New record type.
  (bitlbee-dmd-service): New procedure.
  (%bitlbee-accounts, %bitlbee-activation, bitlbee-service-type): New
  variables.
  (bitlbee-service): Rewrite using 'service'.
  (%wicd-activation): New variable.
  (wicd-dmd-service): New procedure.
  (wicd-service-type): New variable.
  (wicd-service): Rewrite using 'service'.
* gnu/services/ssh.scm (<lsh-configuration>): New record type.
  (activation): Rename to...
  (lsh-initialization): ... this.
  (lsh-activation, lsh-dmd-service, lsh-pam-services): New procedures.
  (lsh-service-type): New variable.
  (lsh-service): Rewrite using 'service' and 'lsh-configuration'.
* gnu/services/web.scm (<nginx-configuration>): New record type.
  (%nginx-accounts): New variable.
  (nginx-activation, nginx-dmd-service): New procedures.
  (nginx-service-type): New variable.
  (nginx-service): Rewrite using 'service' and 'nginx-configuration'.
* gnu/services/xorg.scm (<slim-configuration>): New record type.
  (slim-pam-service, slim-dmd-service): New procedures.
  (slim-service-type): New variable.
  (slim-service): Rewrite using 'service' and 'slim-configuration'.
* gnu/system.scm (file-union): Remove.
  (other-file-system-services): Adjust to new 'file-system-service'
  signature.
  (essential-services): Add #:container? parameter.  Add
  %DMD-ROOT-SERVICE, %ACTIVATION-SERVICE, and calls to
  'pam-root-service', 'account-service', 'operating-system-etc-service',
  and a SETUID-PROGRAM-SERVICE instance.
  (operating-system-services): Pass #:container? to 'essential-services.
  (etc-directory): Remove.
  (operating-system-etc-service): New procedure.  Rewrite as a call to
  'etc-service'.
  (operating-system-accounts): Change to not return accounts required by
  services.
  (operating-system-etc-directory): Rewrite as a call to 'fold-services'
  and 'etc-directory'.
  (user-group->gexp, user-account->gexp, modprobe-wrapper): Remove.
  (operating-system-activation-script): Rewrite as a call to
  'fold-services' and 'activation-service->script'.
  (operating-system-boot-script): Likewise.
  (operating-system-derivation): Add call to 'lower-object'.
  (emacs-site-file, emacs-site-directory, shells-file): Change to use
  'computed-file' and 'scheme-file' instead of the monadic procedures.
* gnu/system/install.scm (cow-store-service-type): New variable.
  (cow-store-service): Rewrite using 'service'.
  (/etc/configuration-files): New procedure.
  (configuration-template-service-type,
  %configuration-template-service): New variables.
  (configuration-template-service): Remove.
  (installation-services): Adjust accordingly.  Adjust argument to
  'guix-service'.
* gnu/system/linux.scm (/etc-entry, pam-root-service): New procedures.
  (pam-root-service-type): New variable.
* gnu/system/shadow.scm (user-group->gexp, user-account->gexp,
  account-activation, etc-skel, account-service): New procedures.
  (account-service-type): New variable.
* tests/services.scm: New file.
* doc/guix.texi (Base Services, Desktop Services): Adjust accordingly.
  (Defining Services): Rewrite.
* doc/images/service-graph.dot: New file.
* doc.am (DOT_FILES): Add it.
* po/guix/POTFILES.in: Add gnu/services.scm.

3 files changed, 182 insertions, 69 deletions

diff --git a/gnu/system/install.scm b/gnu/system/install.scm
index 560d64b5d4..a91c5c3533 100644
--- a/gnu/system/install.scm
+++ b/gnu/system/install.scm
@@ -24,6 +24,7 @@
   #:use-module (guix monads)
   #:use-module ((guix store) #:select (%store-prefix))
   #:use-module (guix profiles)
+  #:use-module (gnu services dmd)
   #:use-module (gnu packages admin)
   #:use-module (gnu packages bash)
   #:use-module (gnu packages linux)
@@ -159,68 +160,74 @@ current store is on a RAM disk."
                (mount "/.rw-store" #$(%store-prefix) "" MS_MOVE)
                (rmdir "/.rw-store"))))))
 
+(define cow-store-service-type
+  (dmd-service-type
+   (lambda _
+     (dmd-service
+      (requirement '(root-file-system user-processes))
+      (provision '(cow-store))
+      (documentation
+       "Make the store copy-on-write, with writes going to \
+the given target.")
+
+      ;; This is meant to be explicitly started by the user.
+      (auto-start? #f)
+
+      (start #~(case-lambda
+                 ((target)
+                  #$(make-cow-store #~target)
+                  target)
+                 (else
+                  ;; Do nothing, and mark the service as stopped.
+                  #f)))
+      (stop #~(lambda (target)
+                ;; Delete the temporary directory, but leave everything
+                ;; mounted as there may still be processes using it since
+                ;; 'user-processes' doesn't depend on us.  The 'user-unmount'
+                ;; service will unmount TARGET eventually.
+                (delete-file-recursively
+                 (string-append target #$%backing-directory))))))))
+
 (define (cow-store-service)
   "Return a service that makes the store copy-on-write, such that writes go to
 the user's target storage device rather than on the RAM disk."
   ;; See <http://bugs.gnu.org/18061> for the initial report.
-  (service
-   (requirement '(root-file-system user-processes))
-   (provision '(cow-store))
-   (documentation
-    "Make the store copy-on-write, with writes going to \
-the given target.")
-
-   ;; This is meant to be explicitly started by the user.
-   (auto-start? #f)
-
-   (start #~(case-lambda
-              ((target)
-               #$(make-cow-store #~target)
-               target)
-              (else
-               ;; Do nothing, and mark the service as stopped.
-               #f)))
-   (stop #~(lambda (target)
-             ;; Delete the temporary directory, but leave everything
-             ;; mounted as there may still be processes using it
-             ;; since 'user-processes' doesn't depend on us.  The
-             ;; 'user-unmount' service will unmount TARGET
-             ;; eventually.
-             (delete-file-recursively
-              (string-append target #$%backing-directory))))))
-
-(define (configuration-template-service)
-  "Return a dummy service whose purpose is to install an operating system
-configuration template file in the installation system."
-
-  (define search
-    (cut search-path %load-path <>))
-  (define templates
-    (map (match-lambda
-           ((file '-> target)
-            (list (local-file (search file))
-                  (string-append "/etc/configuration/" target))))
-         '(("gnu/system/examples/bare-bones.tmpl" -> "bare-bones.scm")
-           ("gnu/system/examples/desktop.tmpl" -> "desktop.scm"))))
-
-  (service
-   (requirement '(root-file-system))
-   (provision '(os-config-template))
-   (documentation
-    "This dummy service installs an OS configuration template.")
-   (start #~(const #t))
-   (stop  #~(const #f))
-   (activate
-    #~(begin
-        (use-modules (ice-9 match)
-                     (guix build utils))
+  (service cow-store-service-type 'mooooh!))
+
+
+(define (/etc/configuration-files _)
+  "Return a list of tuples representing configuration templates to add to
+/etc."
+  (define (file f)
+    (local-file (search-path %load-path
+                             (string-append "gnu/system/examples/" f))))
+
+  (define directory
+    (computed-file "configuration-templates"
+                   #~(begin
+                       (mkdir #$output)
+                       (for-each (lambda (file target)
+                                   (copy-file file
+                                              (string-append #$output "/"
+                                                             target)))
+                                 '(#$(file "bare-bones.tmpl")
+                                   #$(file "desktop.tmpl"))
+                                 '("bare-bones.scm"
+                                   "desktop.scm"))
+                       #t)
+                   #:modules '((guix build utils))))
+
+  `(("configuration" ,directory)))
+
+(define configuration-template-service-type
+  (service-type (name 'configuration-template)
+                (extensions
+                 (list (service-extension etc-service-type
+                                          /etc/configuration-files)))))
+
+(define %configuration-template-service
+  (service configuration-template-service-type #t))
 
-        (mkdir-p "/etc/configuration")
-        (for-each (match-lambda
-                    ((file target)
-                     (unless (file-exists? target)
-                       (copy-file file target))))
-                  '#$templates)))))
 
 (define %nscd-minimal-caches
   ;; Minimal in-memory caching policy for nscd.
@@ -262,7 +269,7 @@ You have been warned.  Thanks for being so brave.
                              (login-program (log-to-info))))
 
           ;; Documentation add-on.
-          (configuration-template-service)
+          %configuration-template-service
 
           ;; A bunch of 'root' ttys.
           (normal-tty "tty3")
@@ -276,7 +283,7 @@ You have been warned.  Thanks for being so brave.
           ;; The build daemon.  Register the hydra.gnu.org key as trusted.
           ;; This allows the installation process to use substitutes by
           ;; default.
-          (guix-service #:authorize-hydra-key? #t)
+          (guix-service (guix-configuration (authorize-key? #t)))
 
           ;; Start udev so that useful device nodes are available.
           ;; Use device-mapper rules for cryptsetup & co; enable the CRDA for
diff --git a/gnu/system/linux.scm b/gnu/system/linux.scm
index 10e72e905a..cd14bc97be 100644
--- a/gnu/system/linux.scm
+++ b/gnu/system/linux.scm
@@ -20,6 +20,7 @@
   #:use-module (guix records)
   #:use-module (guix derivations)
   #:use-module (guix gexp)
+  #:use-module (gnu services)
   #:use-module (ice-9 match)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-26)
@@ -28,7 +29,10 @@
             pam-entry
             pam-services->directory
             unix-pam-service
-            base-pam-services))
+            base-pam-services
+
+            pam-root-service-type
+            pam-root-service))
 
 ;;; Commentary:
 ;;;
@@ -98,8 +102,8 @@ dumped in /etc/pam.d/NAME, where NAME is the name of SERVICE."
 
           (mkdir #$output)
           (for-each (match-lambda
-                     ((name file)
-                      (symlink file (string-append #$output "/" name))))
+                      ((name file)
+                       (symlink file (string-append #$output "/" name))))
 
                     ;; Since <pam-service> objects cannot be compared with
                     ;; 'equal?' since they contain gexps, which contain
@@ -188,4 +192,24 @@ authenticate to run COMMAND."
                '("useradd" "userdel" "usermod"
                  "groupadd" "groupdel" "groupmod"))))
 
+
+;;;
+;;; PAM root service.
+;;;
+
+(define (/etc-entry services)
+  `(("pam.d" ,(pam-services->directory services))))
+
+(define pam-root-service-type
+  (service-type (name 'pam)
+                (extensions (list (service-extension etc-service-type
+                                                     /etc-entry)))
+                (compose concatenate)
+                (extend append)))
+
+(define (pam-root-service base)
+  "The \"root\" PAM service, which collects <pam-service> instance and turns
+them into a /etc/pam.d directory, including the <pam-service> listed in BASE."
+  (service pam-root-service-type base))
+
 ;;; linux.scm ends here
diff --git a/gnu/system/shadow.scm b/gnu/system/shadow.scm
index ddd5f66874..3f49c1fc9f 100644
--- a/gnu/system/shadow.scm
+++ b/gnu/system/shadow.scm
@@ -22,12 +22,14 @@
   #:use-module (guix store)
   #:use-module (guix sets)
   #:use-module (guix ui)
+  #:use-module (gnu services)
   #:use-module ((gnu system file-systems)
                 #:select (%tty-gid))
   #:use-module ((gnu packages admin)
                 #:select (shadow))
   #:use-module (gnu packages bash)
   #:use-module (gnu packages guile-wm)
+  #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-26)
   #:use-module (srfi srfi-34)
   #:use-module (srfi srfi-35)
@@ -54,7 +56,9 @@
             skeleton-directory
             %base-groups
             %base-user-accounts
-            assert-valid-users/groups))
+
+            account-service-type
+            account-service))
 
 ;;; Commentary:
 ;;;
@@ -87,31 +91,32 @@
   (system?        user-group-system?              ; Boolean
                   (default #f)))
 
+
 (define %base-groups
   ;; Default set of groups.
   (let-syntax ((system-group (syntax-rules ()
                                ((_ args ...)
                                 (user-group (system? #t) args ...)))))
     (list (system-group (name "root") (id 0))
-          (system-group (name "wheel"))              ; root-like users
-          (system-group (name "users"))              ; normal users
-          (system-group (name "nogroup"))            ; for daemons etc.
+          (system-group (name "wheel"))           ; root-like users
+          (system-group (name "users"))           ; normal users
+          (system-group (name "nogroup"))         ; for daemons etc.
 
           ;; The following groups are conventionally used by things like udev to
           ;; control access to hardware devices.
           (system-group (name "tty") (id %tty-gid))
           (system-group (name "dialout"))
           (system-group (name "kmem"))
-          (system-group (name "input"))              ; input devices, from udev
+          (system-group (name "input"))           ; input devices, from udev
           (system-group (name "video"))
           (system-group (name "audio"))
-          (system-group (name "netdev"))             ; used in avahi-dbus.conf
+          (system-group (name "netdev"))          ; used in avahi-dbus.conf
           (system-group (name "lp"))
           (system-group (name "disk"))
           (system-group (name "floppy"))
           (system-group (name "cdrom"))
           (system-group (name "tape"))
-          (system-group (name "kvm")))))             ; for /dev/kvm
+          (system-group (name "kvm")))))          ; for /dev/kvm
 
 (define %base-user-accounts
   ;; List of standard user accounts.  Note that "root" is a special case, so
@@ -224,4 +229,81 @@ of user '~a' is undeclared")
                           (user-account-supplementary-groups user)))
               users)))
 
+
+;;;
+;;; Service.
+;;;
+
+(define (user-group->gexp group)
+  "Turn GROUP, a <user-group> object, into a list-valued gexp suitable for
+'active-groups'."
+  #~(list #$(user-group-name group)
+          #$(user-group-password group)
+          #$(user-group-id group)
+          #$(user-group-system? group)))
+
+(define (user-account->gexp account)
+  "Turn ACCOUNT, a <user-account> object, into a list-valued gexp suitable for
+'activate-users'."
+  #~`(#$(user-account-name account)
+      #$(user-account-uid account)
+      #$(user-account-group account)
+      #$(user-account-supplementary-groups account)
+      #$(user-account-comment account)
+      #$(user-account-home-directory account)
+      ,#$(user-account-shell account)             ; this one is a gexp
+      #$(user-account-password account)
+      #$(user-account-system? account)))
+
+(define (account-activation accounts+groups)
+  "Return a gexp that activates ACCOUNTS+GROUPS, a list of <user-account> and
+<user-group> objects.  Raise an error if a user account refers to a undefined
+group."
+  (define accounts
+    (filter user-account? accounts+groups))
+
+  (define user-specs
+    (map user-account->gexp accounts))
+
+  (define groups
+    (filter user-group? accounts+groups))
+
+  (define group-specs
+    (map user-group->gexp groups))
+
+  (assert-valid-users/groups accounts groups)
+
+  ;; Add users and user groups.
+  #~(begin
+      (setenv "PATH"
+              (string-append #$(@ (gnu packages admin) shadow) "/sbin"))
+      (activate-users+groups (list #$@user-specs)
+                             (list #$@group-specs))))
+
+(define (etc-skel arguments)
+  "Filter out among ARGUMENTS things corresponding to skeletons, and return
+the /etc/skel directory for those."
+  (let ((skels (filter pair? arguments)))
+    `(("skel" ,(skeleton-directory skels)))))
+
+(define account-service-type
+  (service-type (name 'account)
+
+                ;; Concatenate <user-account>, <user-group>, and skeleton
+                ;; lists.
+                (compose concatenate)
+                (extend append)
+
+                (extensions
+                 (list (service-extension activation-service-type
+                                          account-activation)
+                       (service-extension etc-service-type
+                                          etc-skel)))))
+
+(define (account-service accounts+groups skeletons)
+  "Return a <service> that takes care of user accounts and user groups, with
+ACCOUNTS+GROUPS as its initial list of accounts and groups."
+  (service account-service-type
+           (append skeletons accounts+groups)))
+
 ;;; shadow.scm ends here