Kuasar: A Multi-Sandbox Container Runtime
Shriira Press
Kuasar is a Rust container runtime that runs microVMs, WebAssembly, app-kernels, and ordinary containers side by side on one node — through a single, unified sandbox abstraction.
Welcome to Kuasar: A Multi-Sandbox Container Runtime.
Kuasar is a low-level, Rust-based container runtime, open-sourced by Huawei in 2023 and accepted into the Cloud Native Computing Foundation as a sandbox project, that answers a question the industry kept dodging: what if a single node needed to run several different isolation technologies at once? A normal container, a hardware-isolated microVM, a WebAssembly module, and an app-kernel sandbox each suit different workloads, yet older runtimes forced them all through a model designed for plain Linux containers. Kuasar rebuilds the runtime around the containerd Sandbox API, treating the sandbox as a first-class citizen and replacing the one-shim-per-container model with a single resident sandboxer. This book moves from the problem and the ecosystem context, through Kuasar's architecture and the Sandbox API, into each sandboxer in turn — microVM, Wasm, app-kernel, and runc — and finishes with how it plugs into containerd and how teams run it in practice. By the end, the layer where containers actually become processes, virtual machines, or modules will be familiar territory.
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