path: root/upstream/fedora-rawhide/man5/sysupdate.d.5

'\" t
.TH "SYSUPDATE\&.D" "5" "" "systemd 255" "sysupdate.d"
.\" -----------------------------------------------------------------
.\" * Define some portability stuff
.\" -----------------------------------------------------------------
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.\" http://bugs.debian.org/507673
.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.ie \n(.g .ds Aq \(aq
.el       .ds Aq '
.\" -----------------------------------------------------------------
.\" * set default formatting
.\" -----------------------------------------------------------------
.\" disable hyphenation
.nh
.\" disable justification (adjust text to left margin only)
.ad l
.\" -----------------------------------------------------------------
.\" * MAIN CONTENT STARTS HERE *
.\" -----------------------------------------------------------------
.SH "NAME"
sysupdate.d \- Transfer Definition Files for Automatic Updates
.SH "SYNOPSIS"
.PP
.nf
/etc/sysupdate\&.d/*\&.conf
/run/sysupdate\&.d/*\&.conf
/usr/lib/sysupdate\&.d/*\&.conf
    
.fi
.SH "DESCRIPTION"
.PP
sysupdate\&.d/*\&.conf
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 \(em but in fact may be used to update any kind of file from a remote source\&.
.PP
The
\fBsystemd-sysupdate\fR(8)
command reads these files and uses them to determine which local resources should be updated, and then executes the update\&.
.PP
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, \&...)\&.
.PP
Each
*\&.conf
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\&.
.PP
Each
*\&.conf
file contains three sections: [Transfer], [Source] and [Target]\&.
.SH "BASIC MODE OF OPERATION"
.PP
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:
.sp
.RS 4
.ie n \{\
\h'-04' 1.\h'+01'\c
.\}
.el \{\
.sp -1
.IP "  1." 4.2
.\}
A file
"https://download\&.example\&.com/foobarOS_47\&.root\&.xz"
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
\m[blue]\fBDiscoverable Partitions Specification\fR\m[]\&\s-2\u[1]\d\s+2\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04' 2.\h'+01'\c
.\}
.el \{\
.sp -1
.IP "  2." 4.2
.\}
Similarly, a file
"https://download\&.example\&.com/foobarOS_47\&.verity\&.xz"
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)\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04' 3.\h'+01'\c
.\}
.el \{\
.sp -1
.IP "  3." 4.2
.\}
Finally, a file
"https://download\&.example\&.com/foobarOS_47\&.efi\&.xz"
(a unified kernel, as per
\m[blue]\fBBoot Loader Specification\fR\m[]\&\s-2\u[2]\d\s+2
Type #2) should be downloaded, decompressed and written to the $BOOT file system, i\&.e\&. to
EFI/Linux/foobarOS_47\&.efi
in the ESP or XBOOTLDR partition\&.
.RE
.PP
The version\-independent generalization of this would be (using the special marker
"@v"
as wildcard for the version identifier):
.sp
.RS 4
.ie n \{\
\h'-04' 1.\h'+01'\c
.\}
.el \{\
.sp -1
.IP "  1." 4.2
.\}
A transfer of a file
"https://download\&.example\&.com/foobarOS_@v\&.root\&.xz"
→ a local, previously empty GPT partition of type 4f68bce3\-e8cd\-4db1\-96e7\-fbcaf984b709, with the label to be set to
"foobarOS_@v"\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04' 2.\h'+01'\c
.\}
.el \{\
.sp -1
.IP "  2." 4.2
.\}
A transfer of a file
"https://download\&.example\&.com/foobarOS_@v\&.verity\&.xz"
→ a local, previously empty GPT partition of type 2c7357ed\-ebd2\-46d9\-aec1\-23d437ec2bf5, with the label to be set to
"foobarOS_@v_verity"\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04' 3.\h'+01'\c
.\}
.el \{\
.sp -1
.IP "  3." 4.2
.\}
A transfer of a file
"https://download\&.example\&.com/foobarOS_@v\&.efi\&.xz"
→ a local file
$BOOT/EFI/Linux/foobarOS_@v\&.efi\&.
.RE
.PP
An update can only complete if the relevant URLs provide their resources for the same version, i\&.e\&. for the same value of
"@v"\&.
.PP
The above may be translated into three
*\&.conf
files in
sysupdate\&.d/, one for each resource to transfer\&. The
*\&.conf
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\&.
.PP
In order to enumerate available versions and figuring out candidates to update to, a mechanism is necessary to list suitable files:
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
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)\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
For regular files: the directory listing of the directory the files are contained in provides a list of existing files in a straightforward way\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
For HTTP/HTTPS sources a simple scheme is used: a manifest file
SHA256SUMS, following the format defined by
\fBsha256sum\fR(1), lists file names and their SHA256 hashes\&.
.RE
.PP
Transfers are done in the alphabetical order of the
\&.conf
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
\fIMatchPattern=\fR, again in the order the
\&.conf
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\&.
.PP
See below for an extended, more specific example based on the above\&.
.SH "RESOURCE TYPES"
.PP
Each transfer file defines one source resource to transfer to one target resource\&. The following resource types are supported:
.sp
.RS 4
.ie n \{\
\h'-04' 1.\h'+01'\c
.\}
.el \{\
.sp -1
.IP "  1." 4.2
.\}
Resources of type
"url\-file"
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
SHA256SUMS
manifest files, accompanied by
SHA256SUMS\&.gpg
detached signatures\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04' 2.\h'+01'\c
.\}
.el \{\
.sp -1
.IP "  2." 4.2
.\}
The
"url\-tar"
resource type is similar, but the file must be a
\&.tar
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
"url\-file",
"url\-tar"
version enumeration makes use of
SHA256SUMS
files, authenticated via
SHA256SUMS\&.gpg\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04' 3.\h'+01'\c
.\}
.el \{\
.sp -1
.IP "  3." 4.2
.\}
The
"regular\-file"
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\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04' 4.\h'+01'\c
.\}
.el \{\
.sp -1
.IP "  4." 4.2
.\}
The
"partition"
resource type is similar to
"regular\-file", 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
"_empty"
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\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04' 5.\h'+01'\c
.\}
.el \{\
.sp -1
.IP "  5." 4.2
.\}
The
"tar"
resource type encapsulates local
\&.tar
archive files\&. When an update takes place, the files are uncompressed and unpacked into a target directory or btrfs subvolume\&. Behaviour of
"tar"
and
"url\-tar"
is generally similar, but the latter downloads from remote sources, and does integrity and authentication checks while the former does not\&. The
"tar"
resource type is only available for source resources\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04' 6.\h'+01'\c
.\}
.el \{\
.sp -1
.IP "  6." 4.2
.\}
The
"directory"
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\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04' 7.\h'+01'\c
.\}
.el \{\
.sp -1
.IP "  7." 4.2
.\}
The
"subvolume"
resource type is identical to
"directory", 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)\&.
.RE
.PP
As already indicated, only a subset of source and target resource type combinations are supported:
.sp
.it 1 an-trap
.nr an-no-space-flag 1
.nr an-break-flag 1
.br
.B Table\ \&1.\ \&Resource Types
.TS
allbox tab(:);
lB lB lB lB lB lB lB lB.
T{
Identifier
T}:T{
Description
T}:T{
Usable as Source
T}:T{
When Used as Source: Compatible Targets
T}:T{
When Used as Source: Integrity + Authentication
T}:T{
When Used as Source: Decompression
T}:T{
Usable as Target
T}:T{
When Used as Target: Compatible Sources
T}
.T&
l l l l l l l l
l l l l l l l l
l l l l l l l l
l l l l l l l l
l l l l l l l l
l l l l l l l l
l l l l l l l l.
T{
\fBurl\-file\fR
T}:T{
HTTP/HTTPS files
T}:T{
yes
T}:T{
\fBregular\-file\fR, \fBpartition\fR
T}:T{
yes
T}:T{
yes
T}:T{
no
T}:T{
\-
T}
T{
\fBurl\-tar\fR
T}:T{
HTTP/HTTPS \&.tar archives
T}:T{
yes
T}:T{
\fBdirectory\fR, \fBsubvolume\fR
T}:T{
yes
T}:T{
yes
T}:T{
no
T}:T{
\-
T}
T{
\fBregular\-file\fR
T}:T{
Local files
T}:T{
yes
T}:T{
\fBregular\-file\fR, \fBpartition\fR
T}:T{
no
T}:T{
yes
T}:T{
yes
T}:T{
\fBurl\-file\fR, \fBregular\-file\fR
T}
T{
\fBpartition\fR
T}:T{
Local GPT partitions
T}:T{
no
T}:T{
\-
T}:T{
\-
T}:T{
\-
T}:T{
yes
T}:T{
\fBurl\-file\fR, \fBregular\-file\fR
T}
T{
\fBtar\fR
T}:T{
Local \&.tar archives
T}:T{
yes
T}:T{
\fBdirectory\fR, \fBsubvolume\fR
T}:T{
no
T}:T{
yes
T}:T{
no
T}:T{
\-
T}
T{
\fBdirectory\fR
T}:T{
Local directories
T}:T{
yes
T}:T{
\fBdirectory\fR, \fBsubvolume\fR
T}:T{
no
T}:T{
no
T}:T{
yes
T}:T{
\fBurl\-tar\fR, \fBtar\fR, \fBdirectory\fR, \fBsubvolume\fR
T}
T{
\fBsubvolume\fR
T}:T{
Local btrfs subvolumes
T}:T{
yes
T}:T{
\fBdirectory\fR, \fBsubvolume\fR
T}:T{
no
T}:T{
no
T}:T{
yes
T}:T{
\fBurl\-tar\fR, \fBtar\fR, \fBdirectory\fR, \fBsubvolume\fR
T}
.TE
.sp 1
.SH "MATCH PATTERNS"
.PP
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
\fIMatchPattern=\fR
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:
.sp
.it 1 an-trap
.nr an-no-space-flag 1
.nr an-break-flag 1
.br
.B Table\ \&2.\ \&Match Pattern Wildcards
.TS
allbox tab(:);
lB lB lB lB.
T{
Wildcard
T}:T{
Description
T}:T{
Format
T}:T{
Notes
T}
.T&
l l l l
l l l l
l l l l
l l l l
l l l l
l l l l
l l l l
l l l l
l l l l
l l l l
l l l l
l l l l.
T{
"@v"
T}:T{
Version identifier
T}:T{
Valid version string
T}:T{
Mandatory
T}
T{
"@u"
T}:T{
GPT partition UUID
T}:T{
Valid 128\-Bit UUID string
T}:T{
Only relevant if target resource type chosen as \fBpartition\fR
T}
T{
"@f"
T}:T{
GPT partition flags
T}:T{
Formatted hexadecimal integer
T}:T{
Only relevant if target resource type chosen as \fBpartition\fR
T}
T{
"@a"
T}:T{
GPT partition flag NoAuto
T}:T{
Either "0" or "1"
T}:T{
Controls NoAuto bit of the GPT partition flags, as per \m[blue]\fBDiscoverable Partitions Specification\fR\m[]\&\s-2\u[1]\d\s+2; only relevant if target resource type chosen as \fBpartition\fR
T}
T{
"@g"
T}:T{
GPT partition flag GrowFileSystem
T}:T{
Either "0" or "1"
T}:T{
Controls GrowFileSystem bit of the GPT partition flags, as per \m[blue]\fBDiscoverable Partitions Specification\fR\m[]\&\s-2\u[1]\d\s+2; only relevant if target resource type chosen as \fBpartition\fR
T}
T{
"@r"
T}:T{
Read\-only flag
T}:T{
Either "0" or "1"
T}:T{
Controls ReadOnly bit of the GPT partition flags, as per \m[blue]\fBDiscoverable Partitions Specification\fR\m[]\&\s-2\u[1]\d\s+2 and other output read\-only flags, see \fIReadOnly=\fR below
T}
T{
"@t"
T}:T{
File modification time
T}:T{
Formatted decimal integer, μs since UNIX epoch Jan 1st 1970
T}:T{
Only relevant if target resource type chosen as \fBregular\-file\fR
T}
T{
"@m"
T}:T{
File access mode
T}:T{
Formatted octal integer, in UNIX fashion
T}:T{
Only relevant if target resource type chosen as \fBregular\-file\fR
T}
T{
"@s"
T}:T{
File size after decompression
T}:T{
Formatted decimal integer
T}:T{
Useful for measuring progress and to improve partition allocation logic
T}
T{
"@d"
T}:T{
Tries done
T}:T{
Formatted decimal integer
T}:T{
Useful when operating with kernel image files, as per \m[blue]\fBAutomatic Boot Assessment\fR\m[]\&\s-2\u[3]\d\s+2
T}
T{
"@l"
T}:T{
Tries left
T}:T{
Formatted decimal integer
T}:T{
Useful when operating with kernel image files, as per \m[blue]\fBAutomatic Boot Assessment\fR\m[]\&\s-2\u[3]\d\s+2
T}
T{
"@h"
T}:T{
SHA256 hash of compressed file
T}:T{
64 hexadecimal characters
T}:T{
The SHA256 hash of the compressed file; not useful for \fBurl\-file\fR or \fBurl\-tar\fR where the SHA256 hash is already included in the manifest file anyway
T}
.TE
.sp 1
.PP
Of these wildcards only
"@v"
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
"MatchPattern=foobar_@v\&.raw\&.xz", i\&.e\&. any file whose name begins with
"foobar_", followed by a version ID and suffixed by
"\&.raw\&.xz"\&.
.PP
Do not confuse the
"@"
pattern matching wildcard prefix with the
"%"
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\&.
.SH "[TRANSFER] SECTION OPTIONS"
.PP
This section defines general properties of this transfer\&.
.PP
\fIMinVersion=\fR
.RS 4
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\&.
.sp
Added in version 251\&.
.RE
.PP
\fIProtectVersion=\fR
.RS 4
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\&.
.sp
Like many of the settings in these configuration files this setting supports specifier expansion\&. It\*(Aqs particularly useful to set this setting to one of the
"%A",
"%B"
or
"%w"
specifiers to automatically refer to the current OS version of the running system\&. See below for details on supported specifiers\&.
.sp
Added in version 251\&.
.RE
.PP
\fIVerify=\fR
.RS 4
Takes a boolean, defaults to yes\&. Controls whether to cryptographically verify downloaded resources (specifically: validate the GPG signatures for downloaded
SHA256SUMS
manifest files, via their detached signature files
SHA256SUMS\&.gpg
in combination with the system keyring
/usr/lib/systemd/import\-pubring\&.gpg
or
/etc/systemd/import\-pubring\&.gpg)\&.
.sp
This option is essential to provide integrity guarantees for downloaded resources and thus should be left enabled, outside of test environments\&.
.sp
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\&.
.sp
This option only has an effect if the source resource type is selected as
\fBurl\-file\fR
or
\fBurl\-tar\fR, as integrity and authentication checking is only available for transfers from remote sources\&.
.sp
Added in version 251\&.
.RE
.SH "[SOURCE] SECTION OPTIONS"
.PP
This section defines properties of the transfer source\&.
.PP
\fIType=\fR
.RS 4
Specifies the resource type of the source for the transfer\&. Takes one of
\fBurl\-file\fR,
\fBurl\-tar\fR,
\fBtar\fR,
\fBregular\-file\fR,
\fBdirectory\fR
or
\fBsubvolume\fR\&. For details about the resource types, see above\&. This option is mandatory\&.
.sp
Note that only certain combinations of source and target resource types are supported, see above\&.
.sp
Added in version 251\&.
.RE
.PP
\fIPath=\fR
.RS 4
Specifies where to find source versions of this resource\&.
.sp
If the source type is selected as
\fBurl\-file\fR
or
\fBurl\-tar\fR
this must be a HTTP/HTTPS URL\&. The URL is suffixed with
/SHA256SUMS
to acquire the manifest file, with
/SHA256SUMS\&.gpg
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\&.
.sp
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\&.
.sp
Added in version 251\&.
.RE
.PP
\fIMatchPattern=\fR
.RS 4
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\&.
.sp
This option is mandatory\&. Any pattern listed must contain at least the
"@v"
wildcard, so that a version identifier may be extracted from the filename\&. All other wildcards are optional\&.
.sp
If the source type is
\fBregular\-file\fR
or
\fBdirectory\fR, the pattern may contain slash characters\&. In this case it will match the file or directory in corresponding subdirectory\&. For example
"MatchPattern=foo_@v/bar\&.efi"
will match
"bar\&.efi"
in directory
"foo_1"\&.
.sp
Added in version 251\&.
.RE
.SH "[TARGET] SECTION OPTIONS"
.PP
This section defines properties of the transfer target\&.
.PP
\fIType=\fR
.RS 4
Specifies the resource type of the target for the transfer\&. Takes one of
\fBpartition\fR,
\fBregular\-file\fR,
\fBdirectory\fR
or
\fBsubvolume\fR\&. For details about the resource types, see above\&. This option is mandatory\&.
.sp
Note that only certain combinations of source and target resource types are supported, see above\&.
.sp
Added in version 251\&.
.RE
.PP
\fIPath=\fR
.RS 4
Specifies a file system path where to look for already installed versions or place newly downloaded versions of this configured resource\&. If
\fIType=\fR
is set to
\fBpartition\fR, expects a path to a (whole) block device node, or the special string
"auto"
in which case the block device which contains the root file system of the currently booted system is automatically determined and used\&. If
\fIType=\fR
is set to
\fBregular\-file\fR,
\fBdirectory\fR
or
\fBsubvolume\fR, must refer to a path in the local file system referencing the directory to find or place the version files or directories under\&.
.sp
Note that this mechanism cannot be used to create or remove partitions, in case
\fIType=\fR
is set to
\fBpartition\fR\&. Partitions must exist already, and a special partition label
"_empty"
is used to indicate empty partitions\&. To automatically generate suitable partitions on first boot, use a tool such as
\fBsystemd-repart\fR(8)\&.
.sp
Added in version 251\&.
.RE
.PP
\fIPathRelativeTo=\fR
.RS 4
Specifies what partition
\fIPath=\fR
should be relative to\&. Takes one of
\fBroot\fR,
\fBesp\fR,
\fBxbootldr\fR, or
\fBboot\fR\&. If unspecified, defaults to
\fBroot\fR\&.
.sp
If set to
\fBboot\fR, the specified
\fIPath=\fR
will be resolved relative to the mount point of the $BOOT partition (i\&.e\&. the ESP or XBOOTLDR), as defined by the
\m[blue]\fBBoot Loader Specification\fR\m[]\&\s-2\u[2]\d\s+2\&.
.sp
The values
\fBesp\fR,
\fBxbootldr\fR, and
\fBboot\fR
are only supported when
\fIType=\fR
is set to
\fBregular\-file\fR
or
\fBdirectory\fR\&.
.sp
Added in version 254\&.
.RE
.PP
\fIMatchPattern=\fR
.RS 4
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\&.
.sp
This option is mandatory\&. Any pattern listed must contain at least the
"@v"
wildcard, so that a version identifier may be extracted from the filename\&. All other wildcards are optional\&.
.sp
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\&.
.sp
If the target type is
\fBregular\-file\fR
or
\fBdirectory\fR, the pattern may contain slash characters\&. In this case it will match the file or directory in corresponding subdirectory\&. For example
"MatchPattern=foo_@v/bar\&.efi"
will match
"bar\&.efi"
in directory
"foo_1"\&. Directories in the path will be created when file is installed\&. Empty directories will be removed when file is removed\&.
.sp
Added in version 251\&.
.RE
.PP
\fIMatchPartitionType=\fR
.RS 4
When the target
\fIType=\fR
is chosen as
\fBpartition\fR, 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
\fBlinux\-generic\fR
is used\&. Accepts either a literal type UUID or a symbolic type identifier\&. For a list of supported type identifiers, see the
\fIType=\fR
setting in
\fBrepart.d\fR(5)\&.
.sp
Added in version 251\&.
.RE
.PP
\fIPartitionUUID=\fR, \fIPartitionFlags=\fR, \fIPartitionNoAuto=\fR, \fIPartitionGrowFileSystem=\fR
.RS 4
When the target
\fIType=\fR
is picked as
\fBpartition\fR, 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\&.
"@u",
"@f",
"@a", or
"@g"), 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
\fIPartitionFlags=\fR
flags setting and the individual flag settings
\fIPartitionNoAuto=\fR
and
\fIPartitionGrowFileSystem=\fR
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
\m[blue]\fBDiscoverable Partitions Specification\fR\m[]\&\s-2\u[1]\d\s+2
for details about these flags\&.
.sp
Note that these settings are not used for matching, they only have effect on newly written partitions in case a transfer takes place\&.
.sp
Added in version 251\&.
.RE
.PP
\fIReadOnly=\fR
.RS 4
Controls whether to mark the resulting file, subvolume or partition read\-only\&. If the target type is
\fBpartition\fR
this controls the ReadOnly partition flag, as per
\m[blue]\fBDiscoverable Partitions Specification\fR\m[]\&\s-2\u[1]\d\s+2, similar to the
\fIPartitionNoAuto=\fR
and
\fIPartitionGrowFileSystem=\fR
flags described above\&. If the target type is
\fBregular\-file\fR, the writable bit is removed from the access mode\&. If the target type is
\fBsubvolume\fR, the subvolume will be marked read\-only as a whole\&. Finally, if the target
\fIType=\fR
is selected as
\fBdirectory\fR, the "immutable" file attribute is set, see
\fBchattr\fR(1)
for details\&.
.sp
Added in version 251\&.
.RE
.PP
\fIMode=\fR
.RS 4
The UNIX file access mode to use for newly created files in case the target resource type is picked as
\fBregular\-file\fR\&. Expects an octal integer, in typical UNIX fashion\&. If not set, but the source match pattern includes a wildcard for this field (i\&.e\&.
"@t"), the value from the pattern is used\&.
.sp
Note that this setting is not used for matching, it only has an effect on newly written files when a transfer takes place\&.
.sp
Added in version 251\&.
.RE
.PP
\fITriesDone=\fR, \fITriesLeft=\fR
.RS 4
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
\m[blue]\fBAutomatic Boot Assessment\fR\m[]\&\s-2\u[3]\d\s+2, and only have an effect if the target pattern includes the
"@d"
or
"@l"
wildcards\&.
.sp
Added in version 251\&.
.RE
.PP
\fIInstancesMax=\fR
.RS 4
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
\fIType=\fR
of
\fBregular\-file\fR,
\fBdirectory\fR,
\fBsubvolume\fR
is used) or emptied (in case the target
\fIType=\fR
of
\fBpartition\fR
is used; emptying in this case simply means to set the partition label to the special string
"_empty"; 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\&.
.sp
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\&.
.sp
If the target
\fIType=\fR
is selected as
\fBpartition\fR, 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\&.
.sp
Added in version 251\&.
.RE
.PP
\fIRemoveTemporary=\fR
.RS 4
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
\fIType=\fR
is selected as
\fBregular\-file\fR,
\fBdirectory\fR
or
\fBsubvolume\fR\&.
.sp
Added in version 251\&.
.RE
.PP
\fICurrentSymlink=\fR
.RS 4
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
\fIType=\fR
is selected as
\fBregular\-file\fR,
\fBdirectory\fR
or
\fBsubvolume\fR\&.
.sp
Added in version 251\&.
.RE
.SH "SPECIFIERS"
.PP
Specifiers may be used in the
\fIMinVersion=\fR,
\fIProtectVersion=\fR,
\fIPath=\fR,
\fIMatchPattern=\fR
and
\fICurrentSymlink=\fR
settings\&. The following expansions are understood:
.sp
.it 1 an-trap
.nr an-no-space-flag 1
.nr an-break-flag 1
.br
.B Table\ \&3.\ \&Specifiers available
.TS
allbox tab(:);
lB lB lB.
T{
Specifier
T}:T{
Meaning
T}:T{
Details
T}
.T&
l l l
l l l
l l l
l l l
l l l
l l l
l l l
l l l
l l l
l l l
l l l
l l l
l l l
l l l
l l l.
T{
"%a"
T}:T{
Architecture
T}:T{
A short string identifying the architecture of the local system\&. A string such as \fBx86\fR, \fBx86\-64\fR or \fBarm64\fR\&. See the architectures defined for \fIConditionArchitecture=\fR in \fBsystemd.unit\fR(5) for a full list\&.
T}
T{
"%A"
T}:T{
Operating system image version
T}:T{
The operating system image version identifier of the running system, as read from the \fIIMAGE_VERSION=\fR field of /etc/os\-release\&. If not set, resolves to an empty string\&. See \fBos-release\fR(5) for more information\&.
T}
T{
"%b"
T}:T{
Boot ID
T}:T{
The boot ID of the running system, formatted as string\&. See \fBrandom\fR(4) for more information\&.
T}
T{
"%B"
T}:T{
Operating system build ID
T}:T{
The operating system build identifier of the running system, as read from the \fIBUILD_ID=\fR field of /etc/os\-release\&. If not set, resolves to an empty string\&. See \fBos-release\fR(5) for more information\&.
T}
T{
"%H"
T}:T{
Host name
T}:T{
The hostname of the running system\&.
T}
T{
"%l"
T}:T{
Short host name
T}:T{
The hostname of the running system, truncated at the first dot to remove any domain component\&.
T}
T{
"%m"
T}:T{
Machine ID
T}:T{
The machine ID of the running system, formatted as string\&. See \fBmachine-id\fR(5) for more information\&.
T}
T{
"%M"
T}:T{
Operating system image identifier
T}:T{
The operating system image identifier of the running system, as read from the \fIIMAGE_ID=\fR field of /etc/os\-release\&. If not set, resolves to an empty string\&. See \fBos-release\fR(5) for more information\&.
T}
T{
"%o"
T}:T{
Operating system ID
T}:T{
The operating system identifier of the running system, as read from the \fIID=\fR field of /etc/os\-release\&. See \fBos-release\fR(5) for more information\&.
T}
T{
"%v"
T}:T{
Kernel release
T}:T{
Identical to \fBuname \-r\fR output\&.
T}
T{
"%w"
T}:T{
Operating system version ID
T}:T{
The operating system version identifier of the running system, as read from the \fIVERSION_ID=\fR field of /etc/os\-release\&. If not set, resolves to an empty string\&. See \fBos-release\fR(5) for more information\&.
T}
T{
"%W"
T}:T{
Operating system variant ID
T}:T{
The operating system variant identifier of the running system, as read from the \fIVARIANT_ID=\fR field of /etc/os\-release\&. If not set, resolves to an empty string\&. See \fBos-release\fR(5) for more information\&.
T}
T{
"%T"
T}:T{
Directory for temporary files
T}:T{
This is either /tmp or the path "$TMPDIR", "$TEMP" or "$TMP" are set to\&. (Note that the directory may be specified without a trailing slash\&.)
T}
T{
"%V"
T}:T{
Directory for larger and persistent temporary files
T}:T{
This is either /var/tmp or the path "$TMPDIR", "$TEMP" or "$TMP" are set to\&. (Note that the directory may be specified without a trailing slash\&.)
T}
T{
"%%"
T}:T{
Single percent sign
T}:T{
Use "%%" in place of "%" to specify a single percent sign\&.
T}
.TE
.sp 1
.PP
Do not confuse the
"%"
specifier expansion prefix with the
"@"
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\&.
.SH "EXAMPLES"
.PP
\fBExample\ \&1.\ \&Updates for a Verity Enabled Secure OS\fR
.PP
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\&.
.PP
.if n \{\
.RS 4
.\}
.nf
# /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
.fi
.if n \{\
.RE
.\}
.PP
The above defines the update mechanism for the Verity partition of the root file system\&. Verity partition images are downloaded from
"https://download\&.example\&.com/foobarOS_@v_@u\&.verity\&.xz"
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
"%A"
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
"roothash="
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
\fBsystemd-gpt-auto-generator\fR(8)
suggests)\&.
.PP
.if n \{\
.RS 4
.\}
.nf
# /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
.fi
.if n \{\
.RE
.\}
.PP
The above defines a matching transfer definition for the root file system\&.
.PP
.if n \{\
.RS 4
.\}
.nf
# /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 \e
             foobarOS_@v+@l\&.efi \e
             foobarOS_@v\&.efi
Mode=0444
TriesLeft=3
TriesDone=0
InstancesMax=2
.fi
.if n \{\
.RE
.\}
.PP
The above installs a unified kernel image into the $BOOT partition, as per
\m[blue]\fBBoot Loader Specification\fR\m[]\&\s-2\u[2]\d\s+2
Type #2\&. This defines three possible patterns for the names of the kernel images, as per
\m[blue]\fBAutomatic Boot Assessment\fR\m[]\&\s-2\u[3]\d\s+2, and ensures when installing new kernels, they are set up with 3 tries left\&. No more than two parallel kernels are kept\&.
.PP
With this setup the web server would serve the following files, for a hypothetical version 7 of the OS:
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
SHA256SUMS
\(en The manifest file, containing available files and their SHA256 hashes
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
SHA256SUMS\&.gpg
\(en The detached cryptographic signature for the manifest file
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
foobarOS_7_8b8186b1\-2b4e\-4eb6\-ad39\-8d4d18d2a8fb\&.verity\&.xz
\(en The Verity image for version 7
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
foobarOS_7_f4d1234f\-3ebf\-47c4\-b31d\-4052982f9a2f\&.root\&.xz
\(en The root file system image for version 7
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
foobarOS_7_efi\&.xz
\(en The unified kernel image for version 7
.RE
.PP
For each new OS release a new set of the latter three files would be added, each time with an updated version\&. The
SHA256SUMS
manifest should then be updated accordingly, listing all files for all versions that shall be offered for download\&.
.PP
\fBExample\ \&2.\ \&Updates for Plain Directory Container Image\fR
.PP
.if n \{\
.RS 4
.\}
.nf
[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
.fi
.if n \{\
.RE
.\}
.PP
On updates this downloads
"https://download\&.example\&.com/myContainer_@v\&.tar\&.gz"
and decompresses/unpacks it to
/var/lib/machines/myContainer_@v\&. After each update a symlink
/var/lib/machines/myContainer
is created/updated always pointing to the most recent update\&.
.SH "SEE ALSO"
.PP
\fBsystemd\fR(1),
\fBsystemd-sysupdate\fR(8),
\fBsystemd-repart\fR(8)
.SH "NOTES"
.IP " 1." 4
Discoverable Partitions Specification
.RS 4
\%https://uapi-group.org/specifications/specs/discoverable_partitions_specification
.RE
.IP " 2." 4
Boot Loader Specification
.RS 4
\%https://uapi-group.org/specifications/specs/boot_loader_specification
.RE
.IP " 3." 4
Automatic Boot Assessment
.RS 4
\%https://systemd.io/AUTOMATIC_BOOT_ASSESSMENT
.RE