Firecracker vs Harvester

Firecracker is open-source virtualization software for running container and function workloads in lightweight microVMs. It uses Linux KVM hardware virtualization to isolate each workload and exposes only five emulated devices, a design intended to reduce attack surface. MicroVMs start in under 125 ms, add under 5 MiB of memory overhead each, and a host can create up to 150 per second while packing thousands onto one server. A RESTful API configures and starts the VMs, while rate limiters govern network and storage bandwidth and operations. The companion jailer adds Linux user-space security barriers. Firecracker supports Linux hosts and guests with kernel versions 4.14 and above, plus OSv guests, on production 64-bit Intel, AMD, and Arm CPUs with hardware virtualization. VM snapshots are supported, but GPU acceleration is not. It is free under Apache 2.0, with integrations including containerd, Kata Containers, and Fly.io.

Harvester is free, open-source hyperconverged infrastructure for bare-metal servers, combining virtualization and distributed storage. It is intended for VMs, Kubernetes running in VMs, containerized workloads on bare metal, and edge workloads. Its architecture uses Kubernetes, KubeVirt, Longhorn, Grafana, Prometheus, and SUSE Linux Micro. Users can create, edit, clone, and delete VMs, with SSH key injection, cloud-init, and graphical or serial consoles. Live migration moves a VM to another host without downtime, but requires matching physical CPU specifications. Storage includes distributed block storage and tiering; VM backups use NFS or S3-compatible targets and are limited to Longhorn volumes. Harvester installs directly on bare metal from a bootable ISO; new installations starting with v1.8 require UEFI boot. Three nodes are needed for multi-node features and high availability, while production recommendations call for at least 16 CPU cores, 64 GB memory, 500 GB disk, and 10 Gbps Ethernet. Laptops and nested virtualization are unsupported.