Add SplitArtifacts=metainfo

GNOME Software parses .metainfo.xml files to provide nice
metadata for artifacts it downloads/updates. Follow the spec
and add parameter for it, filling the content from os-release.

https://www.freedesktop.org/software/appstream/docs/sect-Metadata-OS.html

Author: bluca

mkosi/__init__.py

@@ -388,6 +388,64 @@ def configure_os_release(context: Context) -> None:
         if ArtifactOutput.os_release in context.config.split_artifacts:
             shutil.copy(osrelease, context.staging / context.config.output_split_os_release)
 
+        if ArtifactOutput.metainfo in context.config.split_artifacts:
+            # https://www.freedesktop.org/software/appstream/docs/sect-Metadata-OS.html
+            metainfo = '<?xml version="1.0" encoding="UTF-8"?>\n'
+            metainfo += '<component type="operating-system">\n'
+            id = name = home_url = pretty_name = None
+            for line in osrelease.read_text().splitlines():
+                if line.startswith("ID="):
+                    id = line.split("=")[1].strip('"')
+                elif line.startswith("NAME="):
+                    name = line.split("=")[1].strip('"')
+                elif line.startswith("HOME_URL="):
+                    home_url = line.split("=")[1].strip('"')
+                elif line.startswith("PRETTY_NAME="):
+                    pretty_name = line.split("=")[1].strip('"')
+
+            # The <id> format is reverse DNS style with home_url + id
+            if home_url:
+                from urllib.parse import urlparse
+
+                url = urlparse(home_url)
+                if url.netloc:
+                    netloc = url.netloc.split(".")
+                    netloc.reverse()
+                    netloc.remove("www")
+                    id_field = ".".join(netloc)
+                    if id:
+                        id_field += f".{id}"
+                    metainfo += f"  <id>{id_field}</id>\n"
+            else:
+                metainfo += f"  <id>{id}</id>\n"
+            if name:
+                metainfo += f"  <name>{name}</name>\n"
+            elif context.config.image_id:
+                metainfo += f"  <name>{context.config.image_id}</name>\n"
+            metainfo += f"  <summary>{id} image built with mkosi</summary>\n"
+            if pretty_name:
+                metainfo += f"  <description><p>{pretty_name} built with mkosi</p></description>\n"
+            else:
+                metainfo += "  <description><p>Image built with mkosi</p></description>\n"
+            if home_url:
+                metainfo += f'  <url type="homepage">{home_url}</url>\n'
+            metainfo += (
+                '  <icon type="remote">https://brand.systemd.io/assets/svg/systemd-logomark.svg</icon>\n'
+            )
+            metainfo += "  <metadata_license>FSFAP</metadata_license>\n"
+            metainfo += "  <releases>\n"
+            timestamp = (
+                datetime.datetime.fromtimestamp(context.config.source_date_epoch, tz=datetime.timezone.utc)
+                if context.config.source_date_epoch is not None
+                else datetime.datetime.now(tz=datetime.timezone.utc)
+            ).isoformat()
+            metainfo += f'     <release version="{context.config.image_version}" date="{timestamp}" type="development">\n'  # noqa E501
+            metainfo += "       <description></description>\n"
+            metainfo += "     </release>\n"
+            metainfo += "  </releases>\n"
+            metainfo += "</component>\n"
+            (context.staging / context.config.output_split_metainfo).write_text(metainfo)
+
 
 def configure_extension_release(context: Context) -> None:
     if context.config.output_format not in (OutputFormat.sysext, OutputFormat.confext):

mkosi/config.py

@@ -575,6 +575,7 @@ class ArtifactOutput(StrEnum):
     pcrs = enum.auto()
     roothash = enum.auto()
     os_release = enum.auto()
+    metainfo = enum.auto()
 
     @staticmethod
     def compat_no() -> list["ArtifactOutput"]:
@@ -2132,6 +2133,10 @@ def output_split_roothash(self) -> str:
     def output_split_os_release(self) -> str:
         return f"{self.output}.osrelease"
 
+    @property
+    def output_split_metainfo(self) -> str:
+        return f"{self.output}.metainfo.xml"
+
     @property
     def output_nspawn_settings(self) -> str:
         return f"{self.output}.nspawn"
@@ -2173,6 +2178,7 @@ def outputs(self) -> list[str]:
             self.output_split_pcrs,
             self.output_split_roothash,
             self.output_split_os_release,
+            self.output_split_metainfo,
             self.output_nspawn_settings,
             self.output_checksum,
             self.output_signature,

mkosi/resources/man/mkosi.1.md

@@ -624,7 +624,7 @@ boolean argument: either `1`, `yes`, or `true` to enable, or `0`, `no`,
 `SplitArtifacts=`, `--split-artifacts=`
 :   The artifact types to split out of the final image. A comma-delimited
     list consisting of `uki`, `kernel`, `initrd`, `os-release`, `prcs`, `partitions`,
-    `roothash` and `tar`. When building a bootable image `kernel` and `initrd`
+    `metainfo`, `roothash` and `tar`. When building a bootable image `kernel` and `initrd`
     correspond to their artifact found in the image (or in the UKI),
     while `uki` copies out the entire UKI. If `pcrs` is specified, a JSON
     file containing the pre-calculated TPM2 digests is written out, according

mkosi/resources/mkosi-obs/mkosi.conf

@@ -14,7 +14,7 @@ LocalMirror=file:///.build.binaries/
 [Output]
 OutputDirectory=
 Checksum=yes
-SplitArtifacts=pcrs,roothash
+SplitArtifacts=pcrs,roothash,metainfo
 CompressOutput=zstd
 
 [Validation]