microVMs

MicroVMs are a class of virtualization designed to combine the isolation benefits of virtual machines with the speed and efficiency of containers. They run lightweight virtual machines that host a minimal guest environment, enabling rapid boot times and lower per-instance resource usage. This approach is used to support multi-tenant cloud workloads, serverless platforms, and edge computing where strong isolation and fast scaling are valued.

Architecturally, microVMs rely on hardware-assisted virtualization, typically through a hypervisor such as KVM. Each microVM hosts a small Linux kernel and a compact user-space, plus a limited set of virtual devices (for example, virtio-net for networking and virtio-blk for storage). The emphasis on a minimal guest reduces the memory footprint and boot sequence, allowing large numbers of microVMs to run on a single host while maintaining strong isolation between workloads.

The most prominent implemention is Firecracker, an open-source microVM monitor from AWS that uses KVM to run thousands of microVMs for serverless and containerized workloads. Other approaches in this space include Kata Containers, which provides lightweight VM-based isolation for containers, and related technologies that aim to deliver stronger security boundaries than traditional containers without the full overhead of conventional virtual machines.

Advantages of microVMs include robust isolation comparable to traditional VMs, favorable security properties for multi-tenant environments, and quick deployment and scaling. Limitations involve higher startup latency and resource overhead relative to bare containers, as well as added complexity in managing the lifecycle and tooling for microVMs. Overall, microVMs occupy a niche between containers and full VMs, optimized for secure, scalable cloud workloads.