AppStream is a metadata specification which permits software components to provide information about themselves to automated systems and end-users before the software is actually installed.
The appstream-generator tool generates AppStream metadata from the repositories of a software distribution. It currently supports the following repository formats / distributions: Debian, Ubuntu, Arch Linux, RPM-MD (Fedora, Mageia).
The generator will produce AppStream catalog metadata files in the AppStream YAML or XML format to be shipped to users, as well as a detailed HTML report about found components and HTML and JSON reports on issues detected with the scanned metadata. It reads .desktop files as well as metainfo files, renders fonts, scales images, caches screenshots etc. to produce high-quality metadata for AppStream based software centers to consume. Usually, appstream-generator is integrated with the existing software build & packaging workflow of a distribution.