Ubuntu is updating its Linux distribution for embedded systems, Ubuntu Core, to version 20. It is based on Ubuntu 20 and is thus receiving a fundamental update from the previous version 18. New on board is support for the Raspberry Pi and for deployments with Ubuntu Bare -Metal lifecycle management called Metal as a Service (MaaS).
Basically, Ubuntu Core is a reduced variant of classic Ubuntu for use in embedded environments. The core of the system corresponds to that of its big brother Ubuntu 20 – at least to a large extent, because the first differences arise in the way Ubuntu basically handles its file system. Unlike Ubuntu 20.04 and 20.10, Core relies on a file system in read-only mode, which can only be changed via OverlayFS. Because OverlayFS snapshots can also be used, Ubuntu Core can handle several system states. It can also be reset to an earlier version quickly and easily. This makes the roll back easier if the configuration of an instance goes wrong.
Support for Raspberry Pis
For users, one of the most important innovations is the factory support for the Raspberry Pi, for both the ARMv7 and ARM v8-based versions of the computer. The distribution thus appears as a direct competitor to Raspberry Pi OS – formerly Raspbian -, but differs significantly from this in terms of type and objectives. While Raspberry Pi OS wants to be a universal Linux for the microcomputers, Ubuntu Core is primarily about a platform for the operation of various snaps. The latter is Canonical’s package format based on containers. Applications can be delivered as a single file and operated wherever the runtime environment for Snap is available – including Ubuntu Core. Canonical already offers several ready-made appliances based on distribution, such as OpenHAB or Plex. In the form of Ubuntu Core 20, the provider is bringing the basis for its embedded business up to date with the latest technology.
If you run Ubuntu Core on a system with a Trusted Platform Module (TPM), version 20 or higher can encrypt the hard drive with its help. This currently only works on Intel-compatible computers. The manufacturer plans to provide support for the function on ARM systems later.
On the other hand, the deployment and automatic configuration with Metal as a Service (MaaS) and
cloud-init. Assuming a MaaS instance, embedded devices can be automatically supplied with an operating system such as Ubuntu Core and controlled remotely. MaaS is Canonical’s tool for comprehensive lifecycle management of physical systems.
Own rescue mode
All too often, however, the combination of MaaS and Ubuntu Core should not be found in everyday life. Canonical also provides support for those who want to maintain Ubuntu Core manually and without MaaS. Because Ubuntu Core 20 also comes with a new recovery mode that either starts a root shell for backing up data or initiates a reinstallation of the system. On top of that, Ubuntu Core 20 can build modified images that already have individually selected snaps on board – this saves administrators some of the automation in advance.