services: Export *-service-type and *-configuration.

This allows users to use 'modify-services' and similar constructs for
all these service types.

* gnu/services/avahi.scm: export avahi-configuration.
* gnu/services/base.scm: export gpm-configuration and
rngd-configuration.
* gnu/services/databases.scm: export *-service-type and *-configuration.
* gnu/services/dbus.scm: export dbus-configuration.
* gnu/services/dict.scm: export dicod-service-type.
* gnu/services/lirc.scm: export lirc-configuration and
lirc-service-type.
* gnu/services/mail.scm: export dovecot-service-type.
* gnu/services/web.scm: export nginx-configuration and
nginx-service-type.
* gnu/services/xorg.scm: export screen-locker and screen-locker?.
* gnu/services/ssh.scm: export lsh-configuration and lsh-service-type.
* gnu/services/desktop.scm: export *-service, *-service-type
and *-configuration.
* gnu/services/networking.scm: export *-configuration
and *-service-type.

Co-authored-by: Ludovic Courtès <ludo@gnu.org>

services: Add pam-limits-service.

* gnu/system/pam.scm (<pam-limits-entry>): New record type.
(pam-limits-entry, pam-limits-entry->string): New procedures.
* gnu/services/base.scm (pam-limits-service-type): New variable.
(pam-limits-service): New procedure.
* doc/guix.texi (Base Services): Document it.

services: shepherd: Clarify error message about missing service.

Suggested by Tobias Geerinckx-Rice <me@tobias.gr>.

* gnu/services/shepherd.scm (assert-valid-graph)[assert-satisfied-requirements]:
Clarify error message.

services: dbus: Synchronize startup using dbus-daemon's PID file.

* gnu/services/dbus.scm (dbus-shepherd-service): Pass #:pid-file to
'make-forkexec-constructor'.

services: Add 'dropbear-service'.

* gnu/services/ssh.scm (<dropbear-configuration>): New record type.
(dropbear-activation, dropbear-shepherd-service, dropbear-service): New
procedures.
(dropbear-service-type): New variable.
* doc/guix.texi (Networking Services): Document it.

Co-authored-by: Ludovic Courtès <ludo@gnu.org>

gnu: lsh: Move to (gnu packages ssh)

* gnu/packages/lsh.scm: Remove.  Move 'lsh and liboop' to...
* gnu/packages/ssh.scm (liboop, lsh): ... here.  New variables.
* gnu/services/ssh.scm, gnu/services/base.scm: Adjust accordingly.
* gnu/local.mk (GNU_SYSTEM_MODULES): Adjust accordingly.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

services: <shepherd-service> no longer has an 'imported-modules' field.

* gnu/services/shepherd.scm (<shepherd-service>)[imported-modules]:
Remove.
(%default-imported-modules): Make private.
(shepherd-service-file): Use 'with-imported-modules'.
(shepherd-configuration-file): Remove 'modules' and the calls to
'imported-modules' and 'compiled-modules'.  Use
'with-imported-modules' instead.
* doc/guix.texi (Shepherd Services): Adjust accordingly.
* gnu/services/base.scm (file-system-shepherd-service): Use
'with-imported-modules'.  Remove 'imported-modules' field.
* gnu/system/mapped-devices.scm (device-mapping-service-type): Remove
'imported-modules'.
(open-luks-device): Use 'with-imported-modules'.
* gnu/tests.scm (marionette-shepherd-service): Remove 'imported-modules'
field and use 'with-imported-modules'.

gnu: Switch to 'with-imported-modules'.

* gnu/services.scm (directory-union): Use 'with-imported-modules'
instead of the '#:modules' argument of 'computed-file'.
* gnu/services/base.scm (udev-rules-union): Likewise.
* gnu/services/dbus.scm (system-service-directory): Likewise.
* gnu/services/desktop.scm (wrapped-dbus-service):
(polkit-directory): Likewise.
* gnu/services/networking.scm (tor-configuration->torrc): Likewise.
* gnu/services/xorg.scm (xorg-configuration-directory): Likewise.
* gnu/system/install.scm (self-contained-tarball): Likewise.
* gnu/system/linux-container.scm (container-script): Likewise.
* gnu/system/linux-initrd.scm (expression->initrd): Likewise, and
remove #:modules parameter.
(flat-linux-module-directory): Use 'with-imported-modules'.
(base-initrd): Likewise.
* gnu/system/locale.scm (locale-directory): Likewise.
* gnu/system/shadow.scm (default-skeletons): Likewise.
* gnu/system/vm.scm (expression->derivation-in-linux-vm): Likewise.
* gnu/tests/base.scm (run-basic-test): Likewise.
* gnu/tests/install.scm (run-install): Likewise.
* doc/guix.texi (Initial RAM Disk): Update 'expression->initrd'
documentation.

services: nginx: Fix typo.

* gnu/services/web.scm (nginx-service): Fix typo.

Signed-off-by: Leo Famulari <leo@famulari.name>

services: Add rngd-service.

* gnu/services/base.scm (<rngd-configuration>): New record type.
(rngd-service-type): New variable.
(rngd-service): New procedure.
* doc/guix.texi (Base Services): Document it.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

services: avahi: Add #:debug? parameter.

* gnu/services/avahi.scm (<avahi-configuration>)[debug?]: New field.
(avahi-shepherd-service): Honor it.
(avahi-service): Add #:debug? and honor it.
* doc/guix.texi (Networking Services): Adjust accordingly.

services: avahi: Pass --daemonize and check for the PID file.

This makes sure the service's 'start' finishes when avahi-daemon is
ready to process requests.

* gnu/services/avahi.scm (avahi-shepherd-service): Use --daemonize
instead of --syslog and add #:pid-file.

services: Export more service types.

* gnu/services/base.scm (syslog-service-type): Export.
(urandom-seed-service-type): Export.

services: nscd: Wait for the PID file.

* gnu/services/base.scm (nscd-shepherd-service): Pass #:pid-file.

services: Add 'mcron-service'.

* gnu/services/mcron.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add it.
* gnu/tests/base.scm (%mcron-os, %test-mcron): New variables.
(run-mcron-test): New procedure.
* doc/guix.texi (Scheduled Job Execution): New node.

gnu: services: Add bluetooth-service.

* gnu/services/desktop.scm (bluetooth-shepherd-service)
(bluetooth-service): New Prodecures.
(bluetooth-service-type): New variable.
* doc/guix.text (Desktop Services): Document it.

services: dicod: Add 'interfaces' configuration field.

This makes 'dicod' listen on 'localhost' by default, whereas it was
previously listening on all the interfaces, which is not a good default
security-wise.

* gnu/services/dict.scm (<dicod-configuration>)[interfaces]: New field.
(dicod-configuration-file)[database->text]: New procedure, with code
formerly in 'dicod-configuration->text'.
[dicod-configuration->text]: Rename to...
[configuration->text]: ... this.  Honor 'interfaces'.
* doc/guix.texi (Various Services): Document 'interfaces'.

gnu: services: Add mysql-service.

* gnu/services/database.scm (<mysql-configuration>): New record type.
(%mysql-accounts, mysql-service-type): New variables.
(mysql-configuration-file, %mysql-activation, mysql-shepherd-services)
(mysql-services): New procedures.
* doc/guix.texi (Database Services): Document it.

gnu: services: Add dicod-service.

* gnu/services/dict.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add it.
* doc/guix.texi (Various Services): Document it.

services: urandom-seed: Refresh seed at boot.

* gnu/services/base.scm (urandom-seed-shepherd-service): Refresh the random
seed unconditionally at boot. Ensure directory structure for %random-seed-file
exists when shutting down.
(%urandom-seed-activation): Remove variable.
(urandom-seed-service-type): Remove deleted variable from list of extensions.