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diff --git a/man/sysupdate.d.xml b/man/sysupdate.d.xml new file mode 100644 index 0000000..00b4ac8 --- /dev/null +++ b/man/sysupdate.d.xml @@ -0,0 +1,951 @@ +<?xml version='1.0'?> +<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" + "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> +<!-- SPDX-License-Identifier: LGPL-2.1-or-later --> + +<refentry id="sysupdate.d" conditional='ENABLE_SYSUPDATE' + xmlns:xi="http://www.w3.org/2001/XInclude"> + + <refentryinfo> + <title>sysupdate.d</title> + <productname>systemd</productname> + </refentryinfo> + + <refmeta> + <refentrytitle>sysupdate.d</refentrytitle> + <manvolnum>5</manvolnum> + </refmeta> + + <refnamediv> + <refname>sysupdate.d</refname> + <refpurpose>Transfer Definition Files for Automatic Updates</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <para><literallayout><filename>/etc/sysupdate.d/*.conf</filename> +<filename>/run/sysupdate.d/*.conf</filename> +<filename>/usr/lib/sysupdate.d/*.conf</filename> + </literallayout></para> + </refsynopsisdiv> + + <refsect1> + <title>Description</title> + + <para><filename>sysupdate.d/*.conf</filename> files describe how specific resources on the local system + shall be updated from a remote source. Each such file defines one such transfer: typically a remote + HTTP/HTTPS resource as source; and a local file, directory or partition as target. This may be used as a + simple, automatic, atomic update mechanism for the OS itself, for containers, portable services or system + extension images — but in fact may be used to update any kind of file from a remote source.</para> + + <para>The + <citerefentry><refentrytitle>systemd-sysupdate</refentrytitle><manvolnum>8</manvolnum></citerefentry> + command reads these files and uses them to determine which local resources should be updated, and then + executes the update.</para> + + <para>Both the remote HTTP/HTTPS source and the local target typically exist in multiple, concurrent + versions, in order to implement flexible update schemes, e.g. A/B updating (or a superset thereof, + e.g. A/B/C, A/B/C/D, …).</para> + + <para>Each <filename>*.conf</filename> file defines one transfer, i.e. describes one resource to + update. Typically, multiple of these files (i.e. multiple of such transfers) are defined together, and + are bound together by a common version identifier in order to update multiple resources at once on each + update operation, for example to update a kernel, a root file system and a Verity partition in a single, + combined, synchronized operation, so that only a combined update of all three together constitutes a + complete update.</para> + + <para>Each <filename>*.conf</filename> file contains three sections: [Transfer], [Source] and [Target].</para> + </refsect1> + + <refsect1> + <title>Basic Mode of Operation</title> + + <para>Disk-image based OS updates typically consist of multiple different resources that need to be + updated together, for example a secure OS update might consist of a root file system image to drop into a + partition, a matching Verity integrity data partition image, and a kernel image prepared to boot into the + combination of the two partitions. The first two resources are files that are downloaded and placed in a + disk partition, the latter is a file that is downloaded and placed in a regular file in the boot file + system (e.g. EFI system partition). Hence, during an update of a hypothetical operating system "foobarOS" + to a hypothetical version 47 the following operations should take place:</para> + + <orderedlist> + <listitem><para>A file <literal>https://download.example.com/foobarOS_47.root.xz</literal> should be + downloaded, decompressed and written to a previously unused partition with GPT partition type UUID + 4f68bce3-e8cd-4db1-96e7-fbcaf984b709 for x86-64, as per <ulink + url="https://uapi-group.org/specifications/specs/discoverable_partitions_specification">Discoverable Partitions + Specification</ulink>.</para></listitem> + + <listitem><para>Similarly, a file <literal>https://download.example.com/foobarOS_47.verity.xz</literal> + should be downloaded, decompressed and written to a previously empty partition with GPT partition type + UUID of 2c7357ed-ebd2-46d9-aec1-23d437ec2bf5 (i.e. the partition type for Verity integrity information + for x86-64 root file systems).</para></listitem> + + <listitem><para>Finally, a file <literal>https://download.example.com/foobarOS_47.efi.xz</literal> (a + unified kernel, as per <ulink url="https://uapi-group.org/specifications/specs/boot_loader_specification">Boot Loader + Specification</ulink> Type #2) should be downloaded, decompressed and written to the $BOOT file system, + i.e. to <filename>EFI/Linux/foobarOS_47.efi</filename> in the ESP or XBOOTLDR partition.</para></listitem> + </orderedlist> + + <para>The version-independent generalization of this would be (using the special marker + <literal>@v</literal> as wildcard for the version identifier):</para> + + <orderedlist> + <listitem><para>A transfer of a file <literal>https://download.example.com/foobarOS_@v.root.xz</literal> + → a local, previously empty GPT partition of type 4f68bce3-e8cd-4db1-96e7-fbcaf984b709, with the label to + be set to <literal>foobarOS_@v</literal>.</para></listitem> + + <listitem><para>A transfer of a file <literal>https://download.example.com/foobarOS_@v.verity.xz</literal> + → a local, previously empty GPT partition of type 2c7357ed-ebd2-46d9-aec1-23d437ec2bf5, with the label to be + set to <literal>foobarOS_@v_verity</literal>.</para></listitem> + + <listitem><para>A transfer of a file <literal>https://download.example.com/foobarOS_@v.efi.xz</literal> + → a local file <filename>$BOOT/EFI/Linux/foobarOS_@v.efi</filename>.</para></listitem> + </orderedlist> + + <para>An update can only complete if the relevant URLs provide their resources for the same version, + i.e. for the same value of <literal>@v</literal>.</para> + + <para>The above may be translated into three <filename>*.conf</filename> files in + <filename>sysupdate.d/</filename>, one for each resource to transfer. The <filename>*.conf</filename> + files configure the type of download, and what place to write the download to (i.e. whether to a + partition or a file in the file system). Most importantly these files contain the URL, partition name and + filename patterns shown above that describe how these resources are called on the source and how they + shall be called on the target.</para> + + <para>In order to enumerate available versions and figuring out candidates to update to, a mechanism is + necessary to list suitable files:</para> + + <itemizedlist> + <listitem><para>For partitions: the surrounding GPT partition table contains a list of defined + partitions, including a partition type UUID and a partition label (in this scheme the partition label + plays a role for the partition similar to the filename for a regular file).</para></listitem> + + <listitem><para>For regular files: the directory listing of the directory the files are contained in + provides a list of existing files in a straightforward way.</para></listitem> + + <listitem><para>For HTTP/HTTPS sources a simple scheme is used: a manifest file + <filename>SHA256SUMS</filename>, following the format defined by <citerefentry + project='man-pages'><refentrytitle>sha256sum</refentrytitle><manvolnum>1</manvolnum></citerefentry>, + lists file names and their SHA256 hashes.</para></listitem> + </itemizedlist> + + <para>Transfers are done in the alphabetical order of the <filename>.conf</filename> file names they are + defined in. First, the resource data is downloaded directly into a target file/directory/partition. Once + this is completed for all defined transfers, in a second step the files/directories/partitions are + renamed to their final names as defined by the target <varname>MatchPattern=</varname>, again in the + order the <filename>.conf</filename> transfer file names dictate. This step is not atomic, however it is + guaranteed to be executed strictly in order with suitable disk synchronization in place. Typically, when + updating an OS one of the transfers defines the entry point when booting. Thus it is generally a good idea + to order the resources via the transfer configuration file names so that the entry point is written + last, ensuring that any abnormal termination does not leave an entry point around whose backing is not + established yet. In the example above it would hence make sense to establish the EFI kernel image last + and thus give its transfer configuration file the alphabetically last name.</para> + + <para>See below for an extended, more specific example based on the above.</para> + </refsect1> + + <refsect1> + <title>Resource Types</title> + + <para>Each transfer file defines one source resource to transfer to one target resource. The following + resource types are supported:</para> + + <orderedlist> + + <listitem><para>Resources of type <literal>url-file</literal> encapsulate a file on a web server, + referenced via a HTTP or HTTPS URL. When an update takes place, the file is downloaded and decompressed + and then written to the target file or partition. This resource type is only available for sources, not + for targets. The list of available versions of resources of this type is encoded in + <filename>SHA256SUMS</filename> manifest files, accompanied by + <filename>SHA256SUMS.gpg</filename> detached signatures.</para></listitem> + + <listitem><para>The <literal>url-tar</literal> resource type is similar, but the file must be a + <filename>.tar</filename> archive. When an update takes place, the file is decompressed and unpacked + into a directory or btrfs subvolume. This resource type is only available for sources, not for + targets. Just like <literal>url-file</literal>, <literal>url-tar</literal> version enumeration makes + use of <filename>SHA256SUMS</filename> files, authenticated via + <filename>SHA256SUMS.gpg</filename>.</para></listitem> + + <listitem><para>The <literal>regular-file</literal> resource type encapsulates a local regular file on + disk. During updates the file is uncompressed and written to the target file or partition. This + resource type is available both as source and as target. When updating no integrity or authentication + verification is done for resources of this type.</para></listitem> + + <listitem><para>The <literal>partition</literal> resource type is similar to + <literal>regular-file</literal>, and encapsulates a GPT partition on disk. When updating, the partition + must exist already, and have the correct GPT partition type. A partition whose GPT partition label is + set to <literal>_empty</literal> is considered empty, and a candidate to place a newly downloaded + resource in. The GPT partition label is used to store version information, once a partition is + updated. This resource type is only available for target resources.</para></listitem> + + <listitem><para>The <literal>tar</literal> resource type encapsulates local <filename>.tar</filename> + archive files. When an update takes place, the files are uncompressed and unpacked into a target + directory or btrfs subvolume. Behaviour of <literal>tar</literal> and <literal>url-tar</literal> is + generally similar, but the latter downloads from remote sources, and does integrity and authentication + checks while the former does not. The <literal>tar</literal> resource type is only available for source + resources.</para></listitem> + + <listitem><para>The <literal>directory</literal> resource type encapsulates local directory trees. This + type is available both for source and target resources. If an update takes place on a source resource + of this type, a recursive copy of the directory is done.</para></listitem> + + <listitem><para>The <literal>subvolume</literal> resource type is identical to + <literal>directory</literal>, except when used as the target, in which case the file tree is placed in + a btrfs subvolume instead of a plain directory, if the backing file system supports it (i.e. is + btrfs).</para></listitem> + </orderedlist> + + <para>As already indicated, only a subset of source and target resource type combinations are + supported:</para> + + <table> + <title>Resource Types</title> + + <tgroup cols='3' align='left' colsep='1' rowsep='1'> + <colspec colname="name" /> + <colspec colname="explanation" /> + + <thead> + <row> + <entry>Identifier</entry> + <entry>Description</entry> + <entry>Usable as Source</entry> + <entry>When Used as Source: Compatible Targets</entry> + <entry>When Used as Source: Integrity + Authentication</entry> + <entry>When Used as Source: Decompression</entry> + <entry>Usable as Target</entry> + <entry>When Used as Target: Compatible Sources</entry> + </row> + </thead> + + <tbody> + <row> + <entry><constant>url-file</constant></entry> + <entry>HTTP/HTTPS files</entry> + <entry>yes</entry> + <entry><constant>regular-file</constant>, <constant>partition</constant></entry> + <entry>yes</entry> + <entry>yes</entry> + <entry>no</entry> + <entry>-</entry> + </row> + + <row> + <entry><constant>url-tar</constant></entry> + <entry>HTTP/HTTPS <filename>.tar</filename> archives</entry> + <entry>yes</entry> + <entry><constant>directory</constant>, <constant>subvolume</constant></entry> + <entry>yes</entry> + <entry>yes</entry> + <entry>no</entry> + <entry>-</entry> + </row> + + <row> + <entry><constant>regular-file</constant></entry> + <entry>Local files</entry> + <entry>yes</entry> + <entry><constant>regular-file</constant>, <constant>partition</constant></entry> + <entry>no</entry> + <entry>yes</entry> + <entry>yes</entry> + <entry><constant>url-file</constant>, <constant>regular-file</constant></entry> + </row> + + <row> + <entry><constant>partition</constant></entry> + <entry>Local GPT partitions</entry> + <entry>no</entry> + <entry>-</entry> + <entry>-</entry> + <entry>-</entry> + <entry>yes</entry> + <entry><constant>url-file</constant>, <constant>regular-file</constant></entry> + </row> + + <row> + <entry><constant>tar</constant></entry> + <entry>Local <filename>.tar</filename> archives</entry> + <entry>yes</entry> + <entry><constant>directory</constant>, <constant>subvolume</constant></entry> + <entry>no</entry> + <entry>yes</entry> + <entry>no</entry> + <entry>-</entry> + </row> + + <row> + <entry><constant>directory</constant></entry> + <entry>Local directories</entry> + <entry>yes</entry> + <entry><constant>directory</constant>, <constant>subvolume</constant></entry> + <entry>no</entry> + <entry>no</entry> + <entry>yes</entry> + <entry><constant>url-tar</constant>, <constant>tar</constant>, <constant>directory</constant>, <constant>subvolume</constant></entry> + </row> + + <row> + <entry><constant>subvolume</constant></entry> + <entry>Local btrfs subvolumes</entry> + <entry>yes</entry> + <entry><constant>directory</constant>, <constant>subvolume</constant></entry> + <entry>no</entry> + <entry>no</entry> + <entry>yes</entry> + <entry><constant>url-tar</constant>, <constant>tar</constant>, <constant>directory</constant>, <constant>subvolume</constant></entry> + </row> + + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + <title>Match Patterns</title> + + <para>Both the source and target resources typically exist in multiple versions concurrently. An update + operation is done whenever the newest of the source versions is newer than the newest of the target + versions. To determine the newest version of the resources a directory listing, partition listing or + manifest listing is used, a subset of qualifying entries selected from that, and the version identifier + extracted from the file names or partition labels of these selected entries. Subset selection and + extraction of the version identifier (plus potentially other metadata) is done via match patterns, + configured in <varname>MatchPattern=</varname> in the [Source] and [Target] sections. These patterns are + strings that describe how files or partitions are named, with named wildcards for specific fields such as + the version identifier. The following wildcards are defined:</para> + + <table> + <title>Match Pattern Wildcards</title> + + <tgroup cols='2' align='left' colsep='1' rowsep='1'> + <colspec colname="name" /> + <colspec colname="explanation" /> + + <thead> + <row> + <entry>Wildcard</entry> + <entry>Description</entry> + <entry>Format</entry> + <entry>Notes</entry> + </row> + </thead> + + <tbody> + <row> + <entry><literal>@v</literal></entry> + <entry>Version identifier</entry> + <entry>Valid version string</entry> + <entry>Mandatory</entry> + </row> + + <row> + <entry><literal>@u</literal></entry> + <entry>GPT partition UUID</entry> + <entry>Valid 128-Bit UUID string</entry> + <entry>Only relevant if target resource type chosen as <constant>partition</constant></entry> + </row> + + <row> + <entry><literal>@f</literal></entry> + <entry>GPT partition flags</entry> + <entry>Formatted hexadecimal integer</entry> + <entry>Only relevant if target resource type chosen as <constant>partition</constant></entry> + </row> + + <row> + <entry><literal>@a</literal></entry> + <entry>GPT partition flag NoAuto</entry> + <entry>Either <literal>0</literal> or <literal>1</literal></entry> + <entry>Controls NoAuto bit of the GPT partition flags, as per <ulink url="https://uapi-group.org/specifications/specs/discoverable_partitions_specification">Discoverable Partitions Specification</ulink>; only relevant if target resource type chosen as <constant>partition</constant></entry> + </row> + + <row> + <entry><literal>@g</literal></entry> + <entry>GPT partition flag GrowFileSystem</entry> + <entry>Either <literal>0</literal> or <literal>1</literal></entry> + <entry>Controls GrowFileSystem bit of the GPT partition flags, as per <ulink url="https://uapi-group.org/specifications/specs/discoverable_partitions_specification">Discoverable Partitions Specification</ulink>; only relevant if target resource type chosen as <constant>partition</constant></entry> + </row> + + <row> + <entry><literal>@r</literal></entry> + <entry>Read-only flag</entry> + <entry>Either <literal>0</literal> or <literal>1</literal></entry> + <entry>Controls ReadOnly bit of the GPT partition flags, as per <ulink url="https://uapi-group.org/specifications/specs/discoverable_partitions_specification">Discoverable Partitions Specification</ulink> and other output read-only flags, see <varname>ReadOnly=</varname> below</entry> + </row> + + <row> + <entry><literal>@t</literal></entry> + <entry>File modification time</entry> + <entry>Formatted decimal integer, μs since UNIX epoch Jan 1st 1970</entry> + <entry>Only relevant if target resource type chosen as <constant>regular-file</constant></entry> + </row> + + <row> + <entry><literal>@m</literal></entry> + <entry>File access mode</entry> + <entry>Formatted octal integer, in UNIX fashion</entry> + <entry>Only relevant if target resource type chosen as <constant>regular-file</constant></entry> + </row> + + <row> + <entry><literal>@s</literal></entry> + <entry>File size after decompression</entry> + <entry>Formatted decimal integer</entry> + <entry>Useful for measuring progress and to improve partition allocation logic</entry> + </row> + + <row> + <entry><literal>@d</literal></entry> + <entry>Tries done</entry> + <entry>Formatted decimal integer</entry> + <entry>Useful when operating with kernel image files, as per <ulink url="https://systemd.io/AUTOMATIC_BOOT_ASSESSMENT">Automatic Boot Assessment</ulink></entry> + </row> + + <row> + <entry><literal>@l</literal></entry> + <entry>Tries left</entry> + <entry>Formatted decimal integer</entry> + <entry>Useful when operating with kernel image files, as per <ulink url="https://systemd.io/AUTOMATIC_BOOT_ASSESSMENT">Automatic Boot Assessment</ulink></entry> + </row> + + <row> + <entry><literal>@h</literal></entry> + <entry>SHA256 hash of compressed file</entry> + <entry>64 hexadecimal characters</entry> + <entry>The SHA256 hash of the compressed file; not useful for <constant>url-file</constant> or <constant>url-tar</constant> where the SHA256 hash is already included in the manifest file anyway</entry> + </row> + </tbody> + </tgroup> + </table> + + <para>Of these wildcards only <literal>@v</literal> must be present in a valid pattern, all other + wildcards are optional. Each wildcard may be used at most once in each pattern. A typical wildcard + matching a file system source image could be <literal>MatchPattern=foobar_@v.raw.xz</literal>, i.e. any file + whose name begins with <literal>foobar_</literal>, followed by a version ID and suffixed by + <literal>.raw.xz</literal>.</para> + + <para>Do not confuse the <literal>@</literal> pattern matching wildcard prefix with the + <literal>%</literal> specifier expansion prefix. The former encapsulate a variable part of a match + pattern string, the latter are simple shortcuts that are expanded while the drop-in files are + parsed. For details about specifiers, see below.</para> + </refsect1> + + <refsect1> + <title>[Transfer] Section Options</title> + + <para>This section defines general properties of this transfer.</para> + + <variablelist> + <varlistentry> + <term><varname>MinVersion=</varname></term> + + <listitem><para>Specifies the minimum version to require for this transfer to take place. If the + source or target patterns in this transfer definition match files older than this version they will + be considered obsolete, and never be considered for the update operation.</para> + + <xi:include href="version-info.xml" xpointer="v251"/></listitem> + </varlistentry> + + <varlistentry> + <term><varname>ProtectVersion=</varname></term> + + <listitem><para>Takes one or more version strings to mark as "protected". Protected versions are + never removed while making room for new, updated versions. This is useful to ensure that the + currently booted OS version (or auxiliary resources associated with it) is not replaced/overwritten + during updates, in order to avoid runtime file system corruptions.</para> + + <para>Like many of the settings in these configuration files this setting supports specifier + expansion. It's particularly useful to set this setting to one of the <literal>%A</literal>, + <literal>%B</literal> or <literal>%w</literal> specifiers to automatically refer to the current OS + version of the running system. See below for details on supported specifiers.</para> + + <xi:include href="version-info.xml" xpointer="v251"/></listitem> + </varlistentry> + + <varlistentry> + <term><varname>Verify=</varname></term> + + <listitem><para>Takes a boolean, defaults to yes. Controls whether to cryptographically verify + downloaded resources (specifically: validate the GPG signatures for downloaded + <filename>SHA256SUMS</filename> manifest files, via their detached signature files + <filename>SHA256SUMS.gpg</filename> in combination with the system keyring + <filename>/usr/lib/systemd/import-pubring.gpg</filename> or + <filename>/etc/systemd/import-pubring.gpg</filename>).</para> + + <para>This option is essential to provide integrity guarantees for downloaded resources and thus + should be left enabled, outside of test environments.</para> + + <para>Note that the downloaded payload files are unconditionally checked against the SHA256 hashes + listed in the manifest. This option only controls whether the signatures of these manifests are + verified.</para> + + <para>This option only has an effect if the source resource type is selected as + <constant>url-file</constant> or <constant>url-tar</constant>, as integrity and authentication + checking is only available for transfers from remote sources.</para> + + <xi:include href="version-info.xml" xpointer="v251"/></listitem> + </varlistentry> + + </variablelist> + </refsect1> + + <refsect1> + <title>[Source] Section Options</title> + + <para>This section defines properties of the transfer source.</para> + + <variablelist> + <varlistentry> + <term><varname>Type=</varname></term> + + <listitem><para>Specifies the resource type of the source for the transfer. Takes one of + <constant>url-file</constant>, <constant>url-tar</constant>, <constant>tar</constant>, + <constant>regular-file</constant>, <constant>directory</constant> or + <constant>subvolume</constant>. For details about the resource types, see above. This option is + mandatory.</para> + + <para>Note that only certain combinations of source and target resource types are supported, see + above.</para> + + <xi:include href="version-info.xml" xpointer="v251"/></listitem> + </varlistentry> + </variablelist> + + <variablelist> + <varlistentry> + <term><varname>Path=</varname></term> + + <listitem><para>Specifies where to find source versions of this resource.</para> + + <para>If the source type is selected as <constant>url-file</constant> or + <constant>url-tar</constant> this must be a HTTP/HTTPS URL. The URL is suffixed with + <filename>/SHA256SUMS</filename> to acquire the manifest file, with + <filename>/SHA256SUMS.gpg</filename> to acquire the detached signature file for it, and with the file + names listed in the manifest file in case an update is executed and a resource shall be + downloaded.</para> + + <para>For all other source resource types this must be a local path in the file system, referring to + a local directory to find the versions of this resource in.</para> + + <xi:include href="version-info.xml" xpointer="v251"/></listitem> + </varlistentry> + + <varlistentry> + <term><varname>MatchPattern=</varname></term> + + <listitem><para>Specifies one or more file name match patterns that select the subset of files that + are update candidates as source for this transfer. See above for details on match patterns.</para> + + <para>This option is mandatory. Any pattern listed must contain at least the <literal>@v</literal> + wildcard, so that a version identifier may be extracted from the filename. All other wildcards are + optional.</para> + + <para>If the source type is <constant>regular-file</constant> or <constant>directory</constant>, the + pattern may contain slash characters. In this case it will match the file or directory in + corresponding subdirectory. For example <literal>MatchPattern=foo_@v/bar.efi</literal> will match + <literal>bar.efi</literal> in directory <literal>foo_1</literal>. </para> + + <xi:include href="version-info.xml" xpointer="v251"/></listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>[Target] Section Options</title> + + <para>This section defines properties of the transfer target.</para> + + <variablelist> + <varlistentry> + <term><varname>Type=</varname></term> + + <listitem><para>Specifies the resource type of the target for the transfer. Takes one of + <constant>partition</constant>, <constant>regular-file</constant>, <constant>directory</constant> or + <constant>subvolume</constant>. For details about the resource types, see above. This option is + mandatory.</para> + + <para>Note that only certain combinations of source and target resource types are supported, see + above.</para> + + <xi:include href="version-info.xml" xpointer="v251"/></listitem> + </varlistentry> + + <varlistentry> + <term><varname>Path=</varname></term> + + <listitem><para>Specifies a file system path where to look for already installed versions or place + newly downloaded versions of this configured resource. If <varname>Type=</varname> is set to + <constant>partition</constant>, expects a path to a (whole) block device node, or the special string + <literal>auto</literal> in which case the block device which contains the root file system of the + currently booted system is automatically determined and used. If <varname>Type=</varname> is set to + <constant>regular-file</constant>, <constant>directory</constant> or <constant>subvolume</constant>, + must refer to a path in the local file system referencing the directory to find or place the version + files or directories under.</para> + + <para>Note that this mechanism cannot be used to create or remove partitions, in case + <varname>Type=</varname> is set to <constant>partition</constant>. Partitions must exist already, and + a special partition label <literal>_empty</literal> is used to indicate empty partitions. To + automatically generate suitable partitions on first boot, use a tool such as + <citerefentry><refentrytitle>systemd-repart</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para> + + <xi:include href="version-info.xml" xpointer="v251"/></listitem> + </varlistentry> + + <varlistentry> + <term><varname>PathRelativeTo=</varname></term> + + <listitem><para>Specifies what partition <varname>Path=</varname> should be relative to. Takes one of + <constant>root</constant>, <constant>esp</constant>, <constant>xbootldr</constant>, or <constant>boot</constant>. + If unspecified, defaults to <constant>root</constant>.</para> + + <para>If set to <constant>boot</constant>, the specified <varname>Path=</varname> will be resolved + relative to the mount point of the $BOOT partition (i.e. the ESP or XBOOTLDR), as defined by the + <ulink url="https://uapi-group.org/specifications/specs/boot_loader_specification">Boot Loader + Specification</ulink>.</para> + + <para>The values <constant>esp</constant>, <constant>xbootldr</constant>, and + <constant>boot</constant> are only supported when <varname>Type=</varname> is set to + <constant>regular-file</constant> or <constant>directory</constant>.</para> + + <xi:include href="version-info.xml" xpointer="v254"/></listitem> + </varlistentry> + + <varlistentry> + <term><varname>MatchPattern=</varname></term> + + <listitem><para>Specifies one or more file name or partition label match patterns that select the + subset of files or partitions that are update candidates as targets for this transfer. See above for + details on match patterns.</para> + + <para>This option is mandatory. Any pattern listed must contain at least the <literal>@v</literal> + wildcard, so that a version identifier may be extracted from the filename. All other wildcards are + optional.</para> + + <para>This pattern is both used for matching existing installed versions and for determining the name + of new versions to install. If multiple patterns are specified, the first specified is used for + naming newly installed versions.</para> + + <para>If the target type is <constant>regular-file</constant> or <constant>directory</constant>, the + pattern may contain slash characters. In this case it will match the file or directory in + corresponding subdirectory. For example <literal>MatchPattern=foo_@v/bar.efi</literal> will match + <literal>bar.efi</literal> in directory <literal>foo_1</literal>. Directories in the path will be + created when file is installed. Empty directories will be removed when file is removed.</para> + + <xi:include href="version-info.xml" xpointer="v251"/></listitem> + </varlistentry> + + <varlistentry> + <term><varname>MatchPartitionType=</varname></term> + + <listitem><para>When the target <varname>Type=</varname> is chosen as <constant>partition</constant>, + specifies the GPT partition type to look for. Only partitions of this type are considered, all other + partitions are ignored. If not specified, the GPT partition type <constant>linux-generic</constant> + is used. Accepts either a literal type UUID or a symbolic type identifier. For a list of supported + type identifiers, see the <varname>Type=</varname> setting in + <citerefentry><refentrytitle>repart.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> + + <xi:include href="version-info.xml" xpointer="v251"/></listitem> + </varlistentry> + + <varlistentry> + <term><varname>PartitionUUID=</varname></term> + <term><varname>PartitionFlags=</varname></term> + <term><varname>PartitionNoAuto=</varname></term> + <term><varname>PartitionGrowFileSystem=</varname></term> + + <listitem><para>When the target <varname>Type=</varname> is picked as <constant>partition</constant>, + selects the GPT partition UUID and partition flags to use for the updated partition. Expects a valid + UUID string, a hexadecimal integer, or booleans, respectively. If not set, but the source match + pattern includes wildcards for these fields (i.e. <literal>@u</literal>, <literal>@f</literal>, + <literal>@a</literal>, or <literal>@g</literal>), the values from the patterns are used. If neither + configured with wildcards or these explicit settings, the values are left untouched. If both the + overall <varname>PartitionFlags=</varname> flags setting and the individual flag settings + <varname>PartitionNoAuto=</varname> and <varname>PartitionGrowFileSystem=</varname> are used (or the + wildcards for them), then the latter override the former, i.e. the individual flag bit overrides the + overall flags value. See <ulink url="https://uapi-group.org/specifications/specs/discoverable_partitions_specification">Discoverable + Partitions Specification</ulink> for details about these flags.</para> + + <para>Note that these settings are not used for matching, they only have effect on newly written + partitions in case a transfer takes place.</para> + + <xi:include href="version-info.xml" xpointer="v251"/></listitem> + </varlistentry> + + <varlistentry> + <term><varname>ReadOnly=</varname></term> + + <listitem><para>Controls whether to mark the resulting file, subvolume or partition read-only. If the + target type is <constant>partition</constant> this controls the ReadOnly partition flag, as per + <ulink url="https://uapi-group.org/specifications/specs/discoverable_partitions_specification">Discoverable Partitions + Specification</ulink>, similar to the <varname>PartitionNoAuto=</varname> and + <varname>PartitionGrowFileSystem=</varname> flags described above. If the target type is + <constant>regular-file</constant>, the writable bit is removed from the access mode. If the + target type is <constant>subvolume</constant>, the subvolume will be marked read-only as a + whole. Finally, if the target <varname>Type=</varname> is selected as <constant>directory</constant>, + the "immutable" file attribute is set, see <citerefentry + project='man-pages'><refentrytitle>chattr</refentrytitle><manvolnum>1</manvolnum></citerefentry> for + details.</para> + + <xi:include href="version-info.xml" xpointer="v251"/></listitem> + </varlistentry> + + <varlistentry> + <term><varname>Mode=</varname></term> + + <listitem><para>The UNIX file access mode to use for newly created files in case the target resource + type is picked as <constant>regular-file</constant>. Expects an octal integer, in typical UNIX + fashion. If not set, but the source match pattern includes a wildcard for this field + (i.e. <literal>@t</literal>), the value from the pattern is used.</para> + + <para>Note that this setting is not used for matching, it only has an effect on newly written + files when a transfer takes place.</para> + + <xi:include href="version-info.xml" xpointer="v251"/></listitem> + </varlistentry> + + <varlistentry> + <term><varname>TriesDone=</varname></term> + <term><varname>TriesLeft=</varname></term> + + <listitem><para>These options take positive, decimal integers, and control the number of attempts + done and left for this file. These settings are useful for managing kernel images, following the + scheme defined in <ulink url="https://systemd.io/AUTOMATIC_BOOT_ASSESSMENT">Automatic Boot + Assessment</ulink>, and only have an effect if the target pattern includes the <literal>@d</literal> + or <literal>@l</literal> wildcards.</para> + + <xi:include href="version-info.xml" xpointer="v251"/></listitem> + </varlistentry> + + <varlistentry> + <term><varname>InstancesMax=</varname></term> + + <listitem><para>Takes a decimal integer equal to or greater than 2. This configures how many concurrent + versions of the resource to keep. Whenever a new update is initiated it is made sure that no more + than the number of versions specified here minus one exist in the target. Any excess versions are + deleted (in case the target <varname>Type=</varname> of <constant>regular-file</constant>, + <constant>directory</constant>, <constant>subvolume</constant> is used) or emptied (in case the + target <varname>Type=</varname> of <constant>partition</constant> is used; emptying in this case + simply means to set the partition label to the special string <literal>_empty</literal>; note that no + partitions are actually removed). After an update is completed the number of concurrent versions of + the target resources is equal to or below the number specified here.</para> + + <para>Note that this setting may be set differently for each transfer. However, it generally is + advisable to keep this setting the same for all transfers, since otherwise incomplete combinations of + files or partitions will be left installed.</para> + + <para>If the target <varname>Type=</varname> is selected as <constant>partition</constant>, the number + of concurrent versions to keep is additionally restricted by the number of partition slots of the + right type in the partition table. I.e. if there are only 2 partition slots for the selected + partition type, setting this value larger than 2 is without effect, since no more than 2 concurrent + versions could be stored in the image anyway.</para> + + <xi:include href="version-info.xml" xpointer="v251"/></listitem> + </varlistentry> + + <varlistentry> + <term><varname>RemoveTemporary=</varname></term> + + <listitem><para>Takes a boolean argument. If this option is enabled (which is the default) before + initiating an update, all left-over, incomplete updates from a previous attempt are removed from the + target directory. This only has an effect if the target resource <varname>Type=</varname> is selected + as <constant>regular-file</constant>, <constant>directory</constant> or + <constant>subvolume</constant>.</para> + + <xi:include href="version-info.xml" xpointer="v251"/></listitem> + </varlistentry> + + <varlistentry> + <term><varname>CurrentSymlink=</varname></term> + + <listitem><para>Takes a symlink name as argument. If this option is used, as the last step of the + update a symlink under the specified name is created/updated pointing to the completed update. This + is useful in to provide a stable name always pointing to the newest version of the resource. This is + only supported if the target resource <varname>Type=</varname> is selected as + <constant>regular-file</constant>, <constant>directory</constant> or + <constant>subvolume</constant>.</para> + + <xi:include href="version-info.xml" xpointer="v251"/></listitem> + </varlistentry> + + </variablelist> + </refsect1> + + <refsect1> + <title>Specifiers</title> + + <para>Specifiers may be used in the <varname>MinVersion=</varname>, <varname>ProtectVersion=</varname>, + <varname>Path=</varname>, <varname>MatchPattern=</varname> and <varname>CurrentSymlink=</varname> + settings. The following expansions are understood:</para> + <table class='specifiers'> + <title>Specifiers available</title> + <tgroup cols='3' align='left' colsep='1' rowsep='1'> + <colspec colname="spec" /> + <colspec colname="mean" /> + <colspec colname="detail" /> + <thead> + <row> + <entry>Specifier</entry> + <entry>Meaning</entry> + <entry>Details</entry> + </row> + </thead> + <tbody> + <xi:include href="standard-specifiers.xml" xpointer="a"/> + <xi:include href="standard-specifiers.xml" xpointer="A"/> + <xi:include href="standard-specifiers.xml" xpointer="b"/> + <xi:include href="standard-specifiers.xml" xpointer="B"/> + <xi:include href="standard-specifiers.xml" xpointer="H"/> + <xi:include href="standard-specifiers.xml" xpointer="l"/> + <xi:include href="standard-specifiers.xml" xpointer="m"/> + <xi:include href="standard-specifiers.xml" xpointer="M"/> + <xi:include href="standard-specifiers.xml" xpointer="o"/> + <xi:include href="standard-specifiers.xml" xpointer="v"/> + <xi:include href="standard-specifiers.xml" xpointer="w"/> + <xi:include href="standard-specifiers.xml" xpointer="W"/> + <xi:include href="standard-specifiers.xml" xpointer="T"/> + <xi:include href="standard-specifiers.xml" xpointer="V"/> + <xi:include href="standard-specifiers.xml" xpointer="percent"/> + </tbody> + </tgroup> + </table> + + <para>Do not confuse the <literal>%</literal> specifier expansion prefix with the <literal>@</literal> + pattern matching wildcard prefix. The former are simple shortcuts that are expanded while the drop-in + files are parsed, the latter encapsulate a variable part of a match pattern string. For details about + pattern matching wildcards, see above.</para> + </refsect1> + + <refsect1> + <title>Examples</title> + + <example> + <title>Updates for a Verity Enabled Secure OS</title> + + <para>With the following three files we define a root file system partition, a matching Verity + partition, and a unified kernel image to update as one. This example is an extension of the example + discussed earlier in this man page.</para> + + <para><programlisting># /usr/lib/sysupdate.d/50-verity.conf +[Transfer] +ProtectVersion=%A + +[Source] +Type=url-file +Path=https://download.example.com/ +MatchPattern=foobarOS_@v_@u.verity.xz + +[Target] +Type=partition +Path=auto +MatchPattern=foobarOS_@v_verity +MatchPartitionType=root-verity +PartitionFlags=0 +ReadOnly=1</programlisting></para> + + <para>The above defines the update mechanism for the Verity partition of the root file system. Verity + partition images are downloaded from + <literal>https://download.example.com/foobarOS_@v_@u.verity.xz</literal> and written to a suitable + local partition, which is marked read-only. Under the assumption this update is run from the image + itself the current image version (i.e. the <literal>%A</literal> specifier) is marked as protected, to + ensure it is not corrupted while booted. Note that the partition UUID for the target partition is + encoded in the source file name. Fixating the partition UUID can be useful to ensure that + <literal>roothash=</literal> on the kernel command line is sufficient to pinpoint both the Verity and + root file system partition, and also encode the Verity root level hash (under the assumption the UUID + in the file names match their top-level hash, the way + <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry> + suggests).</para> + + <para><programlisting># /usr/lib/sysupdate.d/60-root.conf +[Transfer] +ProtectVersion=%A + +[Source] +Type=url-file +Path=https://download.example.com/ +MatchPattern=foobarOS_@v_@u.root.xz + +[Target] +Type=partition +Path=auto +MatchPattern=foobarOS_@v +MatchPartitionType=root +PartitionFlags=0 +ReadOnly=1</programlisting></para> + + <para>The above defines a matching transfer definition for the root file system.</para> + + <para><programlisting># /usr/lib/sysupdate.d/70-kernel.conf +[Transfer] +ProtectVersion=%A + +[Source] +Type=url-file +Path=https://download.example.com/ +MatchPattern=foobarOS_@v.efi.xz + +[Target] +Type=regular-file +Path=/EFI/Linux +PathRelativeTo=boot +MatchPattern=foobarOS_@v+@l-@d.efi \ + foobarOS_@v+@l.efi \ + foobarOS_@v.efi +Mode=0444 +TriesLeft=3 +TriesDone=0 +InstancesMax=2</programlisting></para> + + <para>The above installs a unified kernel image into the $BOOT partition, as per + <ulink url="https://uapi-group.org/specifications/specs/boot_loader_specification">Boot Loader + Specification</ulink> Type #2. This defines three possible patterns for the names of the kernel + images, as per <ulink url="https://systemd.io/AUTOMATIC_BOOT_ASSESSMENT">Automatic Boot Assessment</ulink>, + and ensures when installing new kernels, they are set up with 3 tries left. No more than two parallel + kernels are kept.</para> + + <para>With this setup the web server would serve the following files, for a hypothetical version 7 of + the OS:</para> + + <itemizedlist> + <listitem><para><filename>SHA256SUMS</filename> – The manifest file, containing available files and their SHA256 hashes</para></listitem> + <listitem><para><filename>SHA256SUMS.gpg</filename> – The detached cryptographic signature for the manifest file</para></listitem> + <listitem><para><filename>foobarOS_7_8b8186b1-2b4e-4eb6-ad39-8d4d18d2a8fb.verity.xz</filename> – The Verity image for version 7</para></listitem> + <listitem><para><filename>foobarOS_7_f4d1234f-3ebf-47c4-b31d-4052982f9a2f.root.xz</filename> – The root file system image for version 7</para></listitem> + <listitem><para><filename>foobarOS_7_efi.xz</filename> – The unified kernel image for version 7</para></listitem> + </itemizedlist> + + <para>For each new OS release a new set of the latter three files would be added, each time with an + updated version. The <filename>SHA256SUMS</filename> manifest should then be updated accordingly, + listing all files for all versions that shall be offered for download.</para> + </example> + + <example> + <title>Updates for Plain Directory Container Image</title> + + <para><programlisting> +[Source] +Type=url-tar +Path=https://download.example.com/ +MatchPattern=myContainer_@v.tar.gz + +[Target] +Type=subvolume +Path=/var/lib/machines +MatchPattern=myContainer_@v +CurrentSymlink=myContainer</programlisting></para> + + <para>On updates this downloads <literal>https://download.example.com/myContainer_@v.tar.gz</literal> + and decompresses/unpacks it to <filename>/var/lib/machines/myContainer_@v</filename>. After each update + a symlink <filename>/var/lib/machines/myContainer</filename> is created/updated always pointing to the + most recent update.</para> + </example> + </refsect1> + + <refsect1> + <title>See Also</title> + <para> + <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd-sysupdate</refentrytitle><manvolnum>8</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd-repart</refentrytitle><manvolnum>8</manvolnum></citerefentry> + </para> + </refsect1> + +</refentry> |