machine-id-commit: merge machine-id-commit functionality into machine-id-setup

And remove machine-id-commit as separate binary.

There's really no point in keeping this separate, as the sources are
pretty much identical, and have pretty identical interfaces. Let's unify
this in one binary.

Given that machine-id-commit was a private binary of systemd (shipped in
/usr/lib/) removing the tool is not an API break.

While we are at it, improve the documentation of the command substantially.

4 files changed, 101 insertions, 181 deletions

diff --git a/man/machine-id.xml b/man/machine-id.xml
index 92d67a3869..8ce9c46ff1 100644
--- a/man/machine-id.xml
+++ b/man/machine-id.xml
@@ -63,7 +63,7 @@
     <para>The machine ID is usually generated from a random source
     during system installation and stays constant for all subsequent
     boots. Optionally, for stateless systems, it is generated during
-    runtime at boot if it is found to be empty.</para>
+    runtime at early boot if it is found to be empty.</para>
 
     <para>The machine ID does not change based on user configuration
     or when hardware is replaced.</para>
diff --git a/man/systemd-machine-id-commit.service.xml b/man/systemd-machine-id-commit.service.xml
index 7c8fc0874e..10f36b3008 100644
--- a/man/systemd-machine-id-commit.service.xml
+++ b/man/systemd-machine-id-commit.service.xml
@@ -42,55 +42,50 @@
 
   <refnamediv>
     <refname>systemd-machine-id-commit.service</refname>
-    <refpurpose>Commit transient machine-id to disk</refpurpose>
+    <refpurpose>Commit a transient machine-id to disk</refpurpose>
   </refnamediv>
 
   <refsynopsisdiv>
     <para><filename>systemd-machine-id-commit.service</filename></para>
-    <para><filename>/usr/lib/systemd/systemd-machine-id-commit</filename></para>
   </refsynopsisdiv>
 
   <refsect1>
     <title>Description</title>
 
-    <para><filename>systemd-machine-id-commit.service</filename> is a
-    service responsible for committing any transient
-    <filename>/etc/machine-id</filename> file to a writable file
+    <para><filename>systemd-machine-id-commit.service</filename> is an
+    early-boot service responsible for committing transient
+    <filename>/etc/machine-id</filename> files to a writable disk file
     system. See
     <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>
-    for more information about this file.</para>
-
-    <para>This service is started shortly after
-    <filename>local-fs.target</filename> if
-    <filename>/etc/machine-id</filename> is an independent mount point
-    (probably a tmpfs one) and /etc is writable.
-    <command>systemd-machine-id-commit</command> will then write
-    current machine ID to disk and unmount the transient
+    for more information about machine IDs.</para>
+
+    <para>This service is started after
+    <filename>local-fs.target</filename> in case
+    <filename>/etc/machine-id</filename> is a mount point of its own
+    (usually from a memory file system such as
+    <literal>tmpfs</literal>) and /etc is writable. The service will
+    invoke <command>systemd-machine-id-setup --commit</command>, which
+    writes the current transient machine ID to disk and unmount the
     <filename>/etc/machine-id</filename> file in a race-free manner to
-    ensure that file is always valid for other processes.</para>
-
-    <para>Note that the traditional way to initialize the machine ID
-    in <filename>/etc/machine-id</filename> is to use
-    <command>systemd-machine-id-setup</command> by system installer
-    tools. You can also use
-    <citerefentry><refentrytitle>systemd-firstboot</refentrytitle><manvolnum>1</manvolnum></citerefentry>
-    to initialize the machine ID on mounted (but not booted) system
-    images. The main use case for that service is
-    <filename>/etc/machine-id</filename> being an empty file at boot
-    and initrd chaining to systemd giving it a read only file system
-    that will be turned read-write later during the boot
-    process.</para>
-
-    <para>There is no consequence if that service fails other than a
-    newer machine-id will be generated during next system boot.
-    </para>
+    ensure that file is always valid and accessible for other
+    processes. See
+    <citerefentry><refentrytitle>systemd-machine-id-setup</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+    for details.</para>
+
+    <para>The main use case of this service are systems where
+    <filename>/etc/machine-id</filename> is read-only and initially
+    not initialized. In this case the system manager will generate a
+    transient machine ID file on a memory file system, and mount it
+    over <filename>/etc/machine-id</filename>, during the early boot
+    phase. This service is then invoked in a later boot phase, as soon
+    as <filename>/etc</filename> has been remounted writable and the
+    ID may thus be committed to disk to make it permanent.</para>
   </refsect1>
 
   <refsect1>
     <title>See Also</title>
     <para>
       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
-      <citerefentry><refentrytitle>systemd-machine-id-commit</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>systemd-machine-id-setup</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>systemd-firstboot</refentrytitle><manvolnum>1</manvolnum></citerefentry>
diff --git a/man/systemd-machine-id-commit.xml b/man/systemd-machine-id-commit.xml
deleted file mode 100644
index d216aa0745..0000000000
--- a/man/systemd-machine-id-commit.xml
+++ /dev/null
@@ -1,123 +0,0 @@
-<?xml version='1.0'?> <!--*-nxml-*-->
-<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
-  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
-
-<!--
-  This file is part of systemd.
-
-  Copyright 2014 Didier Roche
-
-  systemd is free software; you can redistribute it and/or modify it
-  under the terms of the GNU Lesser General Public License as published by
-  the Free Software Foundation; either version 2.1 of the License, or
-  (at your option) any later version.
-
-  systemd 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
-  Lesser General Public License for more details.
-
-  You should have received a copy of the GNU Lesser General Public License
-  along with systemd; If not, see <http://www.gnu.org/licenses/>.
--->
-
-<refentry id="systemd-machine-id-commit"
-    xmlns:xi="http://www.w3.org/2001/XInclude">
-
-  <refentryinfo>
-    <title>systemd-machine-id-commit</title>
-    <productname>systemd</productname>
-
-    <authorgroup>
-      <author>
-        <contrib>Developer</contrib>
-        <firstname>Didier</firstname>
-        <surname>Roche</surname>
-        <email>didrocks@ubuntu.com</email>
-      </author>
-    </authorgroup>
-  </refentryinfo>
-
-  <refmeta>
-    <refentrytitle>systemd-machine-id-commit</refentrytitle>
-    <manvolnum>1</manvolnum>
-  </refmeta>
-
-  <refnamediv>
-    <refname>systemd-machine-id-commit</refname>
-    <refpurpose>Commit transient machine ID to /etc/machine-id</refpurpose>
-  </refnamediv>
-
-  <refsynopsisdiv>
-    <cmdsynopsis>
-      <command>systemd-machine-id-commit</command>
-    </cmdsynopsis>
-  </refsynopsisdiv>
-
-  <refsect1>
-    <title>Description</title>
-
-    <para><command>systemd-machine-id-commit</command> may be used to
-    write on disk any transient machine ID mounted as a temporary file
-    system in <filename>/etc/machine-id</filename> at boot time. See
-    <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>
-    for more information about this file.</para>
-
-    <para>This tool will execute no operation if
-    <filename>/etc/machine-id</filename> doesn't contain any valid
-    machine ID, isn't mounted as an independent temporary file system,
-    or <filename>/etc</filename> is read-only. If those conditions are
-    met, it will then write current machine ID to disk and unmount the
-    transient <filename>/etc/machine-id</filename> file in a race-free
-    manner to ensure that this file is always valid for other
-    processes.</para>
-
-    <para>Note that the traditional way to initialize the machine ID
-    in <filename>/etc/machine-id</filename> is to use
-    <command>systemd-machine-id-setup</command> by system installer
-    tools. You can also use
-    <citerefentry><refentrytitle>systemd-firstboot</refentrytitle><manvolnum>1</manvolnum></citerefentry>
-    to initialize the machine ID on mounted (but not booted) system
-    images.</para>
-  </refsect1>
-
-  <refsect1>
-    <title>Options</title>
-
-    <para>The following options are understood:</para>
-
-    <variablelist>
-      <varlistentry>
-        <term><option>--root=<replaceable>root</replaceable></option></term>
-        <listitem><para>Takes a directory path
-        as an argument. All paths will be
-        prefixed with the given alternate
-        <replaceable>root</replaceable> path,
-        including config search paths.
-        </para></listitem>
-      </varlistentry>
-      <xi:include href="standard-options.xml" xpointer="help" />
-      <xi:include href="standard-options.xml" xpointer="version" />
-    </variablelist>
-
-  </refsect1>
-
-  <refsect1>
-    <title>Exit status</title>
-
-    <para>On success, 0 is returned, a non-zero failure code
-    otherwise.</para>
-  </refsect1>
-
-  <refsect1>
-    <title>See Also</title>
-    <para>
-      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
-      <citerefentry><refentrytitle>systemd-machine-id-commit.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
-      <citerefentry><refentrytitle>systemd-machine-id-setup</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
-      <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
-      <citerefentry><refentrytitle>systemd-firstboot</refentrytitle><manvolnum>1</manvolnum></citerefentry>
-    </para>
-  </refsect1>
-
-</refentry>
diff --git a/man/systemd-machine-id-setup.xml b/man/systemd-machine-id-setup.xml
index 182717f524..efcf408332 100644
--- a/man/systemd-machine-id-setup.xml
+++ b/man/systemd-machine-id-setup.xml
@@ -1,4 +1,4 @@
-<?xml version='1.0'?> <!--*-nxml-*-->
+<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 
@@ -35,6 +35,12 @@
         <surname>Poettering</surname>
         <email>lennart@poettering.net</email>
       </author>
+      <author>
+        <contrib>Developer</contrib>
+        <firstname>Didier</firstname>
+        <surname>Roche</surname>
+        <email>didrocks@ubuntu.com</email>
+      </author>
     </authorgroup>
   </refentryinfo>
 
@@ -59,30 +65,43 @@
 
     <para><command>systemd-machine-id-setup</command> may be used by
     system installer tools to initialize the machine ID stored in
-    <filename>/etc/machine-id</filename> at install time with a
-    randomly generated ID. See
+    <filename>/etc/machine-id</filename> at install time, with a
+    provisioned or randomly generated ID. See
     <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>
     for more information about this file.</para>
 
-    <para>This tool will execute no operation if
-    <filename>/etc/machine-id</filename> is already
-    initialized.</para>
-
-    <para>If a valid D-Bus machine ID is already configured for the
-    system, the D-Bus machine ID is copied and used to initialize the
-    machine ID in <filename>/etc/machine-id</filename>.</para>
-
-    <para>If run inside a KVM virtual machine and a UUID is passed via
-    the <option>-uuid</option> option, this UUID is used to initialize
-    the machine ID instead of a randomly generated one. The caller
-    must ensure that the UUID passed is sufficiently unique and is
-    different for every booted instanced of the VM.</para>
-
-    <para>Similar, if run inside a Linux container environment and a
-    UUID is set for the container this is used to initialize the
-    machine ID. For details see the documentation of the <ulink
-    url="http://www.freedesktop.org/wiki/Software/systemd/ContainerInterface">Container
-    Interface</ulink>.</para>
+    <para>If the tool is invoked without the <option>--commit</option>
+    switch <filename>/etc/machine-id</filename> is initialized with a
+    valid, new machined ID if it is missing or empty. The new machine
+    ID will be acquired in the following fashion:</para>
+
+    <orderedlist>
+      <listitem><para>If a valid D-Bus machine ID is already
+      configured for the system, the D-Bus machine ID is copied and
+      used to initialize the machine ID in
+      <filename>/etc/machine-id</filename>.</para></listitem>
+
+      <listitem><para>If run inside a KVM virtual machine and a UUID
+      is was configured (via the <option>-uuid</option>
+      option), this UUID is used to initialize the machine ID. The
+      caller must ensure that the UUID passed is sufficiently unique
+      and is different for every booted instance of the
+      VM.</para></listitem>
+
+      <listitem><para>Similar, if run inside a Linux container
+      environment and a UUID is configured for the container this is
+      used to initialize the machine ID. For details see the
+      documentation of the <ulink
+      url="http://www.freedesktop.org/wiki/Software/systemd/ContainerInterface">Container
+      Interface</ulink>.</para></listitem>
+
+      <listitem><para>Otherwise a new ID is randomly
+      generated.</para></listitem>
+    </orderedlist>
+
+    <para>The <option>--commit</option> switch may be used to commit a
+    transient machined ID to disk, making it persistent. For details,
+    see below.</para>
 
     <para>Use
     <citerefentry><refentrytitle>systemd-firstboot</refentrytitle><manvolnum>1</manvolnum></citerefentry>
@@ -97,13 +116,41 @@
     <para>The following options are understood:</para>
 
     <variablelist>
+
       <varlistentry>
         <term><option>--root=<replaceable>root</replaceable></option></term>
-        <listitem><para>Takes a directory path as an argument. All
-        paths will be prefixed with the given alternate
-        <replaceable>root</replaceable> path, including config search
-        paths. </para></listitem>
+        <listitem><para>Takes a directory path as argument. All paths
+        operated will be prefixed with the given alternate
+        <replaceable>root</replaceable> path, including the path for
+        <filename>/etc/machine-id</filename> itself.</para></listitem>
       </varlistentry>
+
+      <varlistentry>
+        <term><option>--commit</option></term>
+        <listitem><para>Commit a transient machine ID to disk. This
+        command may be used to convert a transient machine ID into a
+        persistent one. A transient machine ID file is one that was
+        bind mounted from a memory file system (usually
+        <literal>tmpfs</literal>) to
+        <filename>/etc/machine-id</filename> during the early phase of
+        the boot process. This may happen because
+        <filename>/etc</filename> is initially read-only and was
+        missing a valid machine ID file at that point.</para>
+
+        <para>This command will execute no operation if
+        <filename>/etc/machine-id</filename> is not mounted from a
+        memory file system, or if <filename>/etc</filename> is
+        read-only. The command will write the current transient
+        machine ID to disk and unmount the
+        <filename>/etc/machine-id</filename> mount point in a
+        race-free manner to ensure that this file is always valid and
+        accessible for other processes.</para>
+
+        <para>This command is primarily used by the
+        <citerefentry><refentrytitle>systemd-machine-id-commit.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+        early-boot service.</para></listitem>
+      </varlistentry>
+
       <xi:include href="standard-options.xml" xpointer="help" />
       <xi:include href="standard-options.xml" xpointer="version" />
     </variablelist>
@@ -122,6 +169,7 @@
     <para>
       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>systemd-machine-id-commit.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
       <citerefentry project='dbus'><refentrytitle>dbus-uuidgen</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>systemd-firstboot</refentrytitle><manvolnum>1</manvolnum></citerefentry>
     </para>