diff options
Diffstat (limited to 'man')
| -rw-r--r-- | man/kernel-command-line.xml | 23 | ||||
| -rw-r--r-- | man/systemd-fstab-generator.xml | 46 | ||||
| -rw-r--r-- | man/systemd-nspawn.xml | 15 | ||||
| -rw-r--r-- | man/systemd-volatile-root.service.xml | 79 |
4 files changed, 154 insertions, 9 deletions
diff --git a/man/kernel-command-line.xml b/man/kernel-command-line.xml index 78e45e66a9..7e1d408ded 100644 --- a/man/kernel-command-line.xml +++ b/man/kernel-command-line.xml @@ -125,6 +125,28 @@ </varlistentry> <varlistentry> + <term><varname>systemd.volatile=</varname></term> + <listitem> + <para>This parameter controls whether the system shall boot up in volatile mode. Takes a boolean argument, or + the special value <literal>state</literal>. If false (the default), normal boot mode is selected, the root + directory and <filename>/var</filename> are mounted as specified on the kernel command line or + <filename>/etc/fstab</filename>, or otherwise configured. If true, full state-less boot mode is selected. In + this case the root directory is mounted as volatile memory file system (<literal>tmpfs</literal>), and only + <filename>/usr</filename> is mounted from the file system configured as root device, in read-only mode. This + enables fully state-less boots were the vendor-supplied OS is used as shipped, with only default + configuration and no stored state in effect, as <filename>/etc</filename> and <filename>/var</filename> (as + well as all other resources shipped in the root file system) are reset at boot and lost on shutdown. If this + setting is set to <literal>state</literal> the root file system is mounted as usual, however + <filename>/var</filename> is mounted as a volatile memory file system (<literal>tmpfs</literal>), so that the + system boots up with the normal configuration applied, but all state reset at boot and lost at shutdown. For details, + see + <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> + and + <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para> + </listitem> + </varlistentry> + + <varlistentry> <term><varname>quiet</varname></term> <listitem> <para>Parameter understood by both the kernel and the system @@ -382,6 +404,7 @@ <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>, <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>, <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, diff --git a/man/systemd-fstab-generator.xml b/man/systemd-fstab-generator.xml index a971cb3675..5f37e9193e 100644 --- a/man/systemd-fstab-generator.xml +++ b/man/systemd-fstab-generator.xml @@ -89,12 +89,13 @@ <listitem><para>Takes a boolean argument. Defaults to <literal>yes</literal>. If <literal>no</literal>, causes the - generator to ignore any mounts or swaps configured in + generator to ignore any mounts or swap devices configured in <filename>/etc/fstab</filename>. <varname>rd.fstab=</varname> - is honored only by initial RAM disk (initrd) while + is honored only by the initial RAM disk (initrd) while <varname>fstab=</varname> is honored by both the main system and the initrd.</para></listitem> </varlistentry> + <varlistentry> <term><varname>root=</varname></term> @@ -102,6 +103,7 @@ initrd. <varname>root=</varname> is honored by the initrd.</para></listitem> </varlistentry> + <varlistentry> <term><varname>rootfstype=</varname></term> @@ -109,6 +111,7 @@ passed to the mount command. <varname>rootfstype=</varname> is honored by the initrd.</para></listitem> </varlistentry> + <varlistentry> <term><varname>rootflags=</varname></term> @@ -116,6 +119,7 @@ use. <varname>rootflags=</varname> is honored by the initrd.</para></listitem> </varlistentry> + <varlistentry> <term><varname>mount.usr=</varname></term> @@ -133,6 +137,7 @@ <para><varname>mount.usr=</varname> is honored by the initrd. </para></listitem> </varlistentry> + <varlistentry> <term><varname>mount.usrfstype=</varname></term> @@ -150,6 +155,7 @@ <para><varname>mount.usrfstype=</varname> is honored by the initrd.</para></listitem> </varlistentry> + <varlistentry> <term><varname>mount.usrflags=</varname></term> @@ -166,6 +172,39 @@ <para><varname>mount.usrflags=</varname> is honored by the initrd.</para></listitem> </varlistentry> + + <varlistentry> + <term><varname>systemd.volatile=</varname></term> + + <listitem><para>Controls whether the system shall boot up in volatile mode. Takes a boolean argument or the + special value <option>state</option>.</para> + + <para>If false (the default), this generator makes no changes to the mount tree and the system is booted up in + normal mode.</para> + + <para>If true the generator ensures + <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> + is run as part of the initial RAM disk ("initrd"). This service changes the mount table before transitioning to + the host system, so that a volatile memory file system (<literal>tmpfs</literal>) is used as root directory, + with only <filename>/usr</filename> mounted into it from the configured root file system, in read-only + mode. This way the system operates in fully stateless mode, with all configuration and state reset at boot and + lost at shutdown, as <filename>/etc</filename> and <filename>/var</filename> will be served from the (initially + unpopulated) volatile memory file system.</para> + + <para>If set to <option>state</option> the generator will leave the root + directory mount point unaltered, however will mount a <literal>tmpfs</literal> file system to + <filename>/var</filename>. In this mode the normal system configuration (i.e the contents of + <literal>/etc</literal>) is in effect (and may be modified during system runtime), however the system state + (i.e. the contents of <literal>/var</literal>) is reset at boot and lost at shutdown.</para> + + <para>Note that in none of these modes the root directory, <filename>/etc</filename>, <filename>/var</filename> + or any other resources stored in the root file system are physically removed. It's thus safe to boot a system + that is normally operated in non-volatile mode temporarily into volatile mode, without losing data.</para> + + <para>Note that enabling this setting will only work correctly on operating systems that can boot up with only + <filename>/usr</filename> mounted, and are able to automatically populate <filename>/etc</filename>, and also + <filename>/var</filename> in case of <literal>systemd.volatile=yes</literal>.</para></listitem> + </varlistentry> </variablelist> </refsect1> @@ -176,7 +215,8 @@ <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>, <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>, <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>, - <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry> + <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>, + <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry> </para> </refsect1> diff --git a/man/systemd-nspawn.xml b/man/systemd-nspawn.xml index 2bc81ea1aa..f6b3f57fc7 100644 --- a/man/systemd-nspawn.xml +++ b/man/systemd-nspawn.xml @@ -939,12 +939,15 @@ <option>no</option> (the default), the whole OS tree is made available writable.</para> - <para>Note that setting this to <option>yes</option> or - <option>state</option> will only work correctly with - operating systems in the container that can boot up with only - <filename>/usr</filename> mounted, and are able to populate - <filename>/var</filename> automatically, as - needed.</para></listitem> + <para>This option provides similar functionality for containers as the <literal>systemd.volatile=</literal> + kernel command line switch provides for host systems. See + <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry> for + details.</para> + + <para>Note that enabling this setting will only work correctly with operating systems in the container that can + boot up with only <filename>/usr</filename> mounted, and are able to automatically populate + <filename>/var</filename>, and also <filename>/etc</filename> in case of + <literal>--volatile=yes</literal>.</para></listitem> </varlistentry> <varlistentry> diff --git a/man/systemd-volatile-root.service.xml b/man/systemd-volatile-root.service.xml new file mode 100644 index 0000000000..b90a3261fa --- /dev/null +++ b/man/systemd-volatile-root.service.xml @@ -0,0 +1,79 @@ +<?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 2016 Lennart Poettering + + 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-volatile-root.service"> + + <refentryinfo> + <title>systemd-volatile-root.service</title> + <productname>systemd</productname> + + <authorgroup> + <author> + <contrib>Developer</contrib> + <firstname>Lennart</firstname> + <surname>Poettering</surname> + <email>lennart@poettering.net</email> + </author> + </authorgroup> + </refentryinfo> + + <refmeta> + <refentrytitle>systemd-volatile-root.service</refentrytitle> + <manvolnum>8</manvolnum> + </refmeta> + + <refnamediv> + <refname>systemd-volatile-root.service</refname> + <refname>systemd-volatile-root</refname> + <refpurpose>Make the root file system volatile</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <para><filename>systemd-volatile-root.service</filename></para> + <para><filename>/usr/lib/systemd/systemd-volatile-root</filename></para> + </refsynopsisdiv> + + <refsect1> + <title>Description</title> + + <para><filename>systemd-volatile-root.service</filename> is a service that replaces the root directory with a + volatile memory file system (<literal>tmpfs</literal>), mounting the original (non-volatile) + <filename>/usr</filename> inside it read-only. This way, vendor data from <filename>/usr</filename> is available as + usual, but all configuration data in <filename>/etc</filename>, all state data in <filename>/var</filename> and all + other resources stored directly under the root directory are reset on boot and lost at shutdown, enabling fully + stateless systems.</para> + + <para>This service is only enabled if full volatile mode is selected, for example by specifying + <literal>systemd.volatile=yes</literal> on the kernel command line. This service runs only in the initial RAM disk + ("initrd"), before the system transitions to the host's root directory. Note that this service is not used if + <literal>systemd.volatile=state</literal> is used, as in that mode the root directory is non-volatile.</para> + </refsect1> + + <refsect1> + <title>See Also</title> + <para> + <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>, + <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry> + </para> + </refsect1> + +</refentry> |