sysupdate.features

SYSUPDATE.FEATURES(5) sysupdate.features SYSUPDATE.FEATURES(5)

NAME

   sysupdate.features - Definition Files for Optional Features

SYNOPSIS

       /etc/sysupdate.d/*.feature
       /run/sysupdate.d/*.feature
       /usr/local/lib/sysupdate.d/*.feature
       /usr/lib/sysupdate.d/*.feature

DESCRIPTION

   "Optional Features" are functionality provided by systemd-sysupdate(8), that allow a distribution to define sets of sysupdate.d(5) transfer definitions that are intended to be enabled
   or disabled by the system administrator.

   When a feature is enabled, transfers belonging to it will be considered when checking for and downloading updates, when vacuuming, and in all other situations. In effect, transfers
   belonging to a feature will always be updated in lock-step with the rest of their target. This is the primary difference an Optional Feature and a systemd-sysupdate(8) component. When
   a feature is disabled, its transfers will not be considered when checking for and downloading updates, but systemd-sysupdate will still consider them while vacuuming and in other
   situations where it needs to determine ownership over previously downloaded system resources.  systemd-sysupdate will clean up all instances of the feature's transfers whenever it is
   disabled, effectively uninstalling it.

   Optional Features are described by sysupdate.d/*.feature files, which are defined below. Transfers can declare that they belong to a feature via the Features= setting. Feature
   definitions support drop-in files, which are most commonly used to override the Enabled= setting. They can also be masked to hide the availability of the feature entirely.

   Each *.feature file contains one section: [Feature].

[FEATURE] SECTION OPTIONS

   This section defines general properties of this feature.

   Description=
       A short human readable description of this feature. This may be used as a label for this feature, so the string should meaningfully identify the feature among the features
       available in sysupdate.d/.

       Added in version 257.

   Documentation=
       A user-presentable URL to documentation about this feature. This setting supports specifier expansion; see below for details on supported specifiers.

       Added in version 257.

   AppStream=
       A URL to an AppStream catalog[1] XML file. This may be used by software centers (such as GNOME Software or KDE Discover) to present rich metadata about this feature. This includes
       display names, chagnelogs, icons, and more. This setting supports specifier expansion; see below for details on supported specifiers.

       Added in version 257.

   Enabled=
       Whether or not this feature is enabled. If unspecified, the feature is disabled by default.

       Added in version 257.

SPECIFIERS

   Specifiers may be used in the Documentation= and AppStream= settings. The following expansions are understood:

   Table 1. Specifiers available
   
    Specifier  Meaning                                        Details                                         
   
    "%a"       Architecture                                   A short string identifying the architecture of  
                                                              the local system. A string such as x86, x86-64  
                                                              or arm64. See the architectures defined for     
                                                              ConditionArchitecture= in systemd.unit(5) for a 
                                                              full list.                                      
   
    "%A"       Operating system image version                 The operating system image version identifier   
                                                              of the running system, as read from the         
                                                              IMAGE_VERSION= field of /etc/os-release. If not 
                                                              set, resolves to an empty string. See os-       
                                                              release(5) for more information.                
   
    "%b"       Boot ID                                        The boot ID of the running system, formatted as 
                                                              string. See random(4) for more information.     
   
    "%B"       Operating system build ID                      The operating system build identifier of the    
                                                              running system, as read from the BUILD_ID=      
                                                              field of /etc/os-release. If not set, resolves  
                                                              to an empty string. See os-release(5) for more  
                                                              information.                                    
   
    "%H"       Host name                                      The hostname of the running system.             
   
    "%l"       Short host name                                The hostname of the running system, truncated   
                                                              at the first dot to remove any domain           
                                                              component.                                      
   
    "%m"       Machine ID                                     The machine ID of the running system, formatted 
                                                              as string. See machine-id(5) for more           
                                                              information.                                    
   
    "%M"       Operating system image identifier              The operating system image identifier of the    
                                                              running system, as read from the IMAGE_ID=      
                                                              field of /etc/os-release. If not set, resolves  
                                                              to an empty string. See os-release(5) for more  
                                                              information.                                    
   
    "%o"       Operating system ID                            The operating system identifier of the running  
                                                              system, as read from the ID= field of           
                                                              /etc/os-release. See os-release(5) for more     
                                                              information.                                    
   
    "%v"       Kernel release                                 Identical to uname -r output.                   
   
    "%w"       Operating system version ID                    The operating system version identifier of the  
                                                              running system, as read from the VERSION_ID=    
                                                              field of /etc/os-release. If not set, resolves  
                                                              to an empty string. See os-release(5) for more  
                                                              information.                                    
   
    "%W"       Operating system variant ID                    The operating system variant identifier of the  
                                                              running system, as read from the VARIANT_ID=    
                                                              field of /etc/os-release. If not set, resolves  
                                                              to an empty string. See os-release(5) for more  
                                                              information.                                    
   
    "%T"       Directory for temporary files                  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.)                                         
   
    "%V"       Directory for larger and persistent temporary  This is either /var/tmp or the path "$TMPDIR",  
               files                                          "$TEMP" or "$TMP" are set to. (Note that the    
                                                              directory may be specified without a trailing   
                                                              slash.)                                         
   
    "%%"       Single percent sign                            Use "%%" in place of "%" to specify a single    
                                                              percent sign.                                   
   

EXAMPLES

   Example 1. Development Tools for Image-Based OS

   We'll use the hypothetical "foobarOS" described in sysupdate.d(5) as our example base OS. The vast majority of foobarOS's users have no need for a compiler, build system, debugger,
   and other such development tools to be part of their OS. However, the developers of foobarOS itself need this build tooling to be available. So, foobarOS needs to provide a system
   extension image (see systemd-sysext(8)) containing these development tools, and this image must be updated in lock-step with the underlying base OS. This is a great use case for an
   optional OS feature, so let's define one:

       # /usr/lib/sysupdate.d/devel.feature
       [Feature]
       Description=Development Tools
       Documentation=https://developer.example.com/foobarOS/getting-started
       Enabled=false

   The above defines the "devel" feature, and disables it by default. Now let's a define a transfer that's associated with this feature:

       # /usr/lib/sysupdate.d/50-devel.transfer
       [Transfer]
       Features=devel
       ProtectVersion=%A

       [Source]
       Type=url-file
       Path=https://download.example.com/
       MatchPattern=foobarOS_@v_devel.raw.xz

       [Target]
       Type=regular-file
       Path=/var/lib/extensions
       MatchPattern=foobarOS_@v_devel.raw
       Mode=0444
       InstancesMax=2

   With these two files, we have created a feature called "devel" that, when enabled, will download and decompress the appropriate version of
   "https://download.example.com/foobarOS_@v_devel.raw.xz" into "/var/lib/extensions/foobarOS_@v_devel.raw" during each OS update.

   The developers of foobarOS can enable the "devel" feature on their workstations by creating the following drop-in:

       # /etc/sysupdate.d/devel.feature.d/enable.conf
       [Feature]
       Enabled=true

   Example 2. Proprietary Drivers

   Suppose that many of foobarOS's users have a GPU manufactured by the MVISUAL corporation. Due to lack of documentation and difficulty in reverse-engineering the hardware, the
   open-source drivers for MVISUAL GPUs are unable to make proper use of available graphics and compute performance. MVISUAL provides a redistributable proprietary driver for their
   cards, and foobarOS's developers distribute them to address their users' needs.

   MVISUAL's driver has a couple different parts that must be installed for it to function: a UKI addon to configure the kernel command-line, an initrd system extension image to add the
   MVISUAL kernel module into the initrd, and a regular system extension image to add the proprietary OpenGL and Vulkan userspace drivers. All of these should be version-locked to the
   core OS.

   Let's start by defining an optional feature named "mvisual-driver":

       # /usr/lib/sysupdate.d/mvisual-driver.feature
       [Feature]
       Description=MVISUAL Proprietary GPU Driver
       Documentation=https://support.example.com/foobarOS/mvisual
       AppStream=https://metadata.example.com/mvisual-driver-%A.xml.gz

   Note that we define AppStream metadata for this feature, because we want software centers to present it to end-users. Next, let's define the corresponding transfers:

       # /usr/lib/sysupdate.d/50-mvisual-userspace.transfer
       [Transfer]
       Features=mvisual-driver
       ProtectVersion=%A

       [Source]
       Type=url-file
       Path=https://download.example.com/
       MatchPattern=foobarOS_@v_mvisual_userspace.raw.xz

       [Target]
       Type=regular-file
       Path=/var/lib/extensions
       MatchPattern=foobarOS_@v_mvisual.raw
       Mode=0444
       InstancesMax=2

       # /usr/lib/sysupdate.d/70-mvisual-initrd.transfer
       [Transfer]
       Features=mvisual-driver
       ProtectVersion=%A

       [Source]
       Type=url-file
       Path=https://download.example.com/
       MatchPattern=foobarOS_@v_mvisual_initrd.raw.xz

       [Target]
       Type=regular-file
       Path=/EFI/Linux
       PathRelativeTo=boot
       MatchPattern=foobarOS_@v.efi.extra.d/foobarOS_mvisual.raw
       Mode=0444
       InstancesMax=2

       # /usr/lib/sysupdate.d/90-mvisual-addon.transfer
       [Transfer]
       Features=mvisual-driver
       ProtectVersion=%A

       [Source]
       Type=url-file
       Path=https://download.example.com/
       MatchPattern=foobarOS_@v_mvisual_addon.efi.xz

       [Target]
       Type=regular-file
       Path=/EFI/Linux
       PathRelativeTo=boot
       MatchPattern=foobarOS_@v.efi.extra.d/foobarOS_mvisual.addon.efi
       Mode=0444
       InstancesMax=2

   Example 3. Intersecting Features

   Suppose that MVISUAL releases special tooling to help a distribution developer troubleshoot crashes in their proprietary driver. Let's define a transfer:

       # /usr/lib/sysupdate.d/50-mvisual-debugger.transfer
       [Transfer]
       RequisiteFeatures=devel mvisual-driver
       ProtectVersion=%A

       [Source]
       Type=url-file
       Path=https://download.example.com/
       MatchPattern=foobarOS_@v_devel.raw.xz

       [Target]
       Type=regular-file
       Path=/var/lib/extensions
       MatchPattern=foobarOS_@v_devel.raw
       Mode=0444
       InstancesMax=2

   This transfer will be used only if both the "devel" and "mvisual-driver" features are enabled.

SEE ALSO

   systemd(1), systemd-sysupdate(8), sysupdate.d(5)

NOTES

    1. AppStream catalog
       https://www.freedesktop.org/software/appstream/docs/chap-CatalogData.html

systemd 257.7 SYSUPDATE.FEATURES(5)