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Firecracker

INFRA · APIS
Velocity3.8

Secure and fast microVM manager for serverless workloads

firecracker-microvm.github.io ↗

Firecracker can now run microVMs on Nitro instead of KVM, with the same API.

microvmvirtualizationconfidential computingaws nitroopen source
◆Current state
Firecracker is the open-source microVM monitor behind AWS Lambda and Fargate. 2026 brought PCI virtio hotplug in developer preview (1.16), virtio device reset and richer metrics (1.17), and now 1.18.0 adds Nitro Sandboxes: Firecracker can drive the Nitro Enclaves driver instead of /dev/kvm to launch VMs the Nitro Hypervisor carves out of the parent EC2 instance. The existing API, jailer and virtio device model stay the same, and a new PUT /enclave endpoint selects confidential or direct mode.
◆Where it's heading
The project is widening what a Firecracker microVM can be without changing how operators drive it: hotplug and reset made the VM lifecycle more flexible, and Nitro support makes the hypervisor backend swappable. Patch releases keep landing on several stable lines at once, so the maintainers are supporting older minors while the feature surface grows.
◆Prediction
Expect 1.18.x patches that fix Nitro Sandbox edge cases and documentation on which devices and snapshot features work in confidential mode; the release does not say whether Nitro support will leave preview or reach feature parity with KVM.

◆Recent moves

  1. 4d ago

    Firecracker 1.18 runs microVMs on Nitro, not just KVM

    ⚡ SPARK

    1.18.0 is the first release to give Firecracker a second hypervisor backend. It follows the 1.16 and 1.17 lifecycle work by keeping the operator API unchanged while swapping what sits underneath it.

    View source ↗
  2. 2mo ago

    Firecracker 1.17: virtio device reset and richer metrics

    v1.17.0 adds virtio device reset and two opt-in metrics fields, instance ID and operator-defined key-value properties. It continues the 1.16 lifecycle work and is the release that 1.18's Nitro backend now builds on.

    View source ↗
  3. 2mo ago

    Firecracker v1.16.2

    v1.16.2 is a targeted fix for a CPU cache topology regression on host kernels in the 6.3–6.10 range and a snapshot format version bump — both breaking for users on affected kernel ranges or holding cross-version snapshots, but not user-visible capability changes.

    View source ↗
  4. 4mo ago

    Firecracker v1.16.1

    v1.16.1 reverts a symlink restriction that broke jailer workflows and fixes a vsock TX queue timeout regression after snapshot restore — targeted fixes for specific operational failure modes introduced in v1.16.0.

    View source ↗
  5. 5mo ago

    Firecracker v1.16.0

    ⚡ SPARK

    PCI virtio device hotplugging in developer preview is the most significant microVM lifecycle capability in Firecracker's recent history — the ability to attach and detach block, pmem, and network devices from a running microVM without a cold restart opens dynamic workload configurations that previously required full reinitialization.

    View source ↗
  6. 7mo ago

    Firecracker v1.14.4

    v1.14.4 is a backport patch release — specific fixes applied to the stable 1.14.x line for users not yet on 1.15 or 1.16, typically addressing critical or security-relevant issues without the newer minor's changes.

    View source ↗