Add a machineid module.

The module creates /etc/machine-id and/or /var/lib/dbus/machine-id. By
default, it is enabled and creates both files, making the latter a
symlink to the former.

settings.conf

@@ -34,6 +34,7 @@ install:
 - partition
 - mount
 - unpackfs
+- machineid
 - fstab
 - locale
 - keyboard

src/modules/machineid/machineid.conf

+---
+# Whether to create /etc/machine-id for systemd.
+systemd: true
+# Whether to create /var/lib/dbus/machine-id for D-Bus.
+dbus: true
+# Whether /var/lib/dbus/machine-id should be a symlink to /etc/machine-id
+# (ignored if dbus is false, or if there is no /etc/machine-id to point to).
+symlink: true

src/modules/machineid/main.py

+#!/usr/bin/env python3
+# encoding: utf-8
+# === This file is part of Calamares - <http://github.com/calamares> ===
+#
+# Copyright 2014, Kevin Kofler <kevin.kofler@chello.at>
+#
+# Calamares is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Calamares is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Calamares. If not, see <http://www.gnu.org/licenses/>.
+
+import libcalamares
+import os
+
+
+def run():
+    root_mount_point = libcalamares.globalstorage.value("rootMountPoint")
+    enable_systemd = libcalamares.job.configuration["systemd"]
+    enable_dbus = libcalamares.job.configuration["dbus"]
+    enable_symlink = libcalamares.job.configuration["symlink"]
+    target_systemd_machineid_file = "{}/etc/machine-id".format(root_mount_point)
+    if enable_systemd:
+        if os.path.exists(target_systemd_machineid_file):
+            os.remove(target_systemd_machineid_file)
+        check_chroot_call("systemd-machine-id-setup")
+    if enable_dbus:
+        target_dbus_machineid_file = "{}/var/lib/dbus/machine-id".format(root_mount_point)
+        if os.path.exists(target_dbus_machineid_file):
+            os.remove(target_dbus_machineid_file)
+        if enable_symlink and os.path.exists(target_systemd_machineid_file):
+            check_chroot_call(["ln", "-s", "/etc/machine-id", "/var/lib/dbus/machine-id"])
+        else:
+            check_chroot_call(["dbus-uuidgen", "--ensure"])
+    return None