gnu: Add 'inputs' field to <user-account>; make 'shell' a monadic value.

* gnu/system/shadow.scm (<user-account>)[inputs]: New field.
  (passwd-file): Bind the 'shell' field of each account.
* gnu/system/vm.scm (%demo-operating-system): Remove 'shell' field.
* gnu/system/dmd.scm (guix-build-accounts): Store a monadic value in
  'shell'.  Add 'inputs' field.
* gnu/system.scm (operating-system-derivation): Remove 'shell' field for
  'root' account.  Add all the 'user-account-inputs' to EXTRAS.

gnu: dmd: Avoid "already exists" error on startup.

* gnu/system/dmd.scm (dmd-configuration-file)[config]: Remove
  "/var/nix/gcroots/etc-directory" before trying to recreate it.

gnu: Populate /etc upon startup.

* gnu/packages/patches/dmd-getpw.patch: New file.
* gnu-system.am (dist_patch_DATA): Add it.
* gnu/packages/system.scm (dmd): Use it.
* gnu/system/vm.scm (system-qemu-image): Don't explicitly populate /etc;
  don't add ETC to the GC roots.
* gnu/system/dmd.scm (dmd-configuration-file): Add 'etc' parameter.
  [config]: Populate /etc from there.

gnu: dmd: Add 'pam-services' field to <service>.

* gnu/system/dmd.scm (<service>)[pam-services]: New field.
  (mingetty-service): Add #:motd and #:allow-empty-passwords?
  parameters.  Add MOTD to 'inputs' field; add 'pam-services' field.
* gnu/system/vm.scm (system-qemu-image): Aggregate PAM entries from
  SERVICES.

gnu: dmd: Add 'user-accounts' and 'user-groups' fields to <service>.

* gnu/system/shadow.scm (guix-build-accounts): Move to...
* gnu/system/dmd.scm (guix-build-accounts): ... here.
  (<service>)[user-accounts, user-groups]: New fields.
  (guix-service): New #:build-user-id and #:build-accounts parameters.
  Use 'guix-build-accounts' and set the 'user-accounts' and
  'user-groups' fields accordingly.
* gnu/system/vm.scm (system-qemu-image): Remove use of
  'guix-build-accounts'.  Augment ACCOUNTS and GROUPS from what SERVICES
  demand.

gnu: Move /etc/resolv.conf handling to the networking service.

* gnu/system/vm.scm (etc-directory): Remove 'resolv.conf'.
  (system-qemu-image): Use 'static-networking-service' with
  #:name-servers.  Don't populate the image with /etc/resolv.conf.
* gnu/system/dmd.scm (static-networking-service): Add #:name-servers
  parameter.  Use it to populate /etc/resolv.conf.

gnu: dmd: Update start/stop of standard service definitions.

* gnu/system/dmd.scm (mingetty-service): Add 'stop' field.
  (nscd-service): Run with '--foreground'.  Change 'stop' to use
  'make-kill-destructor'.
  (syslog-service): Run with '--no-detach'; change 'stop' similarly.
  (guix-service): Likewise for 'stop'.
  (static-networking-service): Remove 'sleep' call from 'start'.  Change
  'stop' to return #f when networking was actually stopped.

gnu: dmd: Add service documentation.

* gnu/system/dmd.scm (<service>): Add 'documentation' field.
  (host-name-service, mingetty-service, nscd-service, syslog-service,
  static-networking-service): Provide a 'documentation' value.
  (dmd-configuration-file): Use it.

gnu: vm: Rewrite helper functions as monadic functions.

* gnu/system/dmd.scm (host-name-service, nscd-service, mingetty-service,
  syslog-service, guix-service, static-networking-service): Rewrite as
  monadic functions.
  (dmd-configuration-file): Use 'text-file' instead of
  'add-text-to-store'.
* gnu/system/grub.scm (grub-configuration-file): Rewrite as a monadic
  function.
* gnu/system/linux.scm (pam-services->directory): Likewise.
* gnu/system/shadow.scm (group-file, passwd-file, guix-build-accounts):
  Likewise.
* gnu/system/vm.scm (expression->derivation-in-linux-vm, qemu-image,
  union, system-qemu-image): Likewise.

gnu: dmd: Make the 'networking' service slightly more robust.

* gnu/system/dmd.scm (static-networking-service)[start]: Sleep before
  running 'route', to leave time for the interface to come up.
  [stop]: Run "route del -net default".

gnu: vm: Add build users.

* gnu/system/shadow.scm (guix-build-accounts): New procedure.
* gnu/system/vm.scm (system-qemu-image): Use it.  Add the "guixbuild"
  group.
* gnu/system/dmd.scm (guix-service): Add 'builder-group' parameter.
  Pass 'guix-daemon' the '--build-users-group' option.

gnu: vm: Set the default networking route.

* gnu/system/dmd.scm (static-networking-service): Add #:gateway
  parameter and honor it.
* gnu/system/vm.scm (system-qemu-image): Pass #:gateway to
  'static-networking-service'.

Merge branch 'master' into core-updates

gnu: vm: Add nscd service.

* gnu/system/dmd.scm (nscd-service): New procedure.
* gnu/system/vm.scm (system-qemu-image): Use it.  Make /var/run/nscd.

gnu: vm: Add 'networking' service.

* gnu/system/vm.scm (system-qemu-image): Use
  'static-networking-service'.  Add /etc/resolv.conf.  Add Inetutils to
  the profile.
* gnu/system/dmd.scm (static-networking-service): New procedure.

gnu: vm: Add 'host-name' service.

* gnu/system/dmd.scm (host-name-service): New procedure.
  (mingetty-service): Require the 'host-name' service.
* gnu/system/vm.scm (system-qemu-image): Add the 'host-name' service.
  Set PS1 in /etc/bashrc to something sensible.

gnu: vm: Add a service for the Guix daemon.

* gnu/system/dmd.scm (guix-service): New procedure.
* gnu/system/vm.scm (system-qemu-image): Use it.

Merge branch 'master' into core-updates

gnu: QEMU images boots into dmd.

* gnu/system/dmd.scm: New file.
* gnu/system/vm.scm (system-qemu-image): Define dmd services.
  [populate]: Make var/log and etc/group.
  [boot]: Execute dmd directly.
  Add dmd and etc-group as inputs; add the inputs of dmd services.
* gnu-system.am (GNU_SYSTEM_MODULES): Add gnu/system/dmd.scm.