Poettering: The Wondrous World of Discoverable GPT Disk Images

In a lengthyblog post, Lennart Poettering describes the advantages of using theunique IDs (UUIDs) and flags from the discoverable partitionsspecification to label the entries in a GUID PartitionTable (GPT). That information can be used to tag disk images in aself-descriptive way, so that external configuration files (such as/etc/fstab) are not needed to assemble the filesystems for therunning system. Systemd can use this information in a variety of ways,including for running the image in a container: "If a disk imagefollows the Discoverable Partition Specification then systemd-nspawn hasall it needs to just boot it up. Specifically, if you have a GPT disk imagein a file foobar.raw and you want to boot it up in a container, just runsystemd-nspawn -i foobar.raw -b, and that's it (you can specify a blockdevice like /dev/sdb too if you like). It becomes easy and natural toprepare disk images that can be booted either on a physical machine, insidea virtual machine manager or inside such a container manager: the necessarymeta-information is included in the image, easily accessible beforeactually looking into its file systems."