FTL is a userspace OS design that lets you build your own OS as a library. It isolates containers better than existing monolithic kernels, using a hypervisor-like interface based on lightweight hardware-based isolation. You don't need bare-metal machines, and FTL is compatible with Linux binaries. For example, the Rust-based HTTP server serving this website is a Linux application running on FTL. You can also run Unikernel-like specialized applications without POSIX abstractions.
Each container runs a userspace OS, which is a shared library implementing most OS concepts such as Linux process, VFS, and TCP/IP. The FTL kernel provides a minimal interface to implement Linux system calls in userspace, just like a hypervisor. FTL combines the best of microkernels (flexible & secure) and monolithic kernels (performant & simple). The goal is to make lightweight containers as secure as VMs, and unlock new OS-level abilities in applications, without sacrificing performance.
The userspace OS design also enables you to extend most of Linux kernel features without kernel/eBPF programming. You can add printfs, apply security updates, and add new features quickly and safely. In FTL, OS is just a library. The roadmap includes running a simple Linux HTTP server on FTL in September 2026 (v0.0.1), async Rust apps support in October 2026 (v0.1.0), filesystem in November 2026, Node.js/Go support in December 2026, and SMP, container images, and 64-bit Arm support in January 2027.
Source: Hacker News · Summarized by HeadlinesBriefing