GravityKit
GravityKit ships weekly across a whole plugin suite, with an MCP server now part of the lineup.
Comparison · Infra & APIs
Firecracker vs Gatekeeper
A side-by-side editorial comparison of Firecracker and Gatekeeper — release velocity, themes, recent moves, and the top alternatives to consider.
Firecracker vs Gatekeeper: at a glance
What is Firecracker?
Firecracker's microVMs can now grow and shrink devices while running.
1.16.0 in June added developer-preview hotplug and hot-unplug for PCI virtio block, pmem and net devices on a live microVM, with the guest responsible for rescanning the bus and removing the device first since no notification mechanism exists yet. The same release added vsock Unix socket path overriding on snapshot restore, rate limiting for serial console output with a dropped-bytes metric, and per-callsite log rate limiting. 1.16.1 followed with a vsock fix for connections timing out after restore when a snapshot caught an in-flight TX descriptor. Earlier in the window, 1.15.0 added the VMClock device and Intel Granite Rapids support, and the April patches hardened the PCI transport against CVE-2026-5747.
What is Gatekeeper?
Gatekeeper grew a package manager for policies — and a benchmark to prove they are not too slow.
3.22.0-rc.0 in February introduced two CLI subcommands that change how policies are handled rather than what they express: gator policy, a brew-inspired tool for discovering, installing, upgrading and uninstalling policies from the gatekeeper-library, and gator bench, which benchmarks Rego and CEL engines with latency percentiles, throughput, memory profiling and baseline comparison for CI regression detection. The same release enabled sync-vap-enforcement-scope by default and gave both CEL and Rego access to namespace context during admission and audit. Since then, 3.23.0-rc.1 added status resource routing for remote cluster mode, and 3.24.0-beta.0 made generated ValidatingAdmissionPolicy output deterministic to stop a reconcile loop.
Firecracker vs Gatekeeper: editorial side-by-side
Firecracker
0.0INFRA · APIS
Firecracker's microVMs can now grow and shrink devices while running.
◆ Current state
1.16.0 in June added developer-preview hotplug and hot-unplug for PCI virtio block, pmem and net devices on a live microVM, with the guest responsible for rescanning the bus and removing the device first since no notification mechanism exists yet. The same release added vsock Unix socket path overriding on snapshot restore, rate limiting for serial console output with a dropped-bytes metric, and per-callsite log rate limiting. 1.16.1 followed with a vsock fix for connections timing out after restore when a snapshot caught an in-flight TX descriptor. Earlier in the window, 1.15.0 added the VMClock device and Intel Granite Rapids support, and the April patches hardened the PCI transport against CVE-2026-5747.
◆ Where it's heading
The through-line is snapshots and the PCI transport maturing together. Firecracker's value has always been fast boot from a snapshot, and the recent fixes are all in the seams that opens up — TX descriptors in flight when a snapshot is taken, vsock paths that change on restore, virtio device state machines that must be validated the same way on PCI as on MMIO. Hotplug extends the same idea from restore-time to run-time: a microVM that can change shape is one you can keep rather than replace.
◆ Prediction
Hotplug shipped explicitly as a developer preview requiring manual guest bus rescans, so the stated gap is an automatic notification mechanism. That is the obvious next step before the feature leaves preview.
Gatekeeper
2.5INFRA · APIS
Gatekeeper grew a package manager for policies — and a benchmark to prove they are not too slow.
◆ Current state
3.22.0-rc.0 in February introduced two CLI subcommands that change how policies are handled rather than what they express: gator policy, a brew-inspired tool for discovering, installing, upgrading and uninstalling policies from the gatekeeper-library, and gator bench, which benchmarks Rego and CEL engines with latency percentiles, throughput, memory profiling and baseline comparison for CI regression detection. The same release enabled sync-vap-enforcement-scope by default and gave both CEL and Rego access to namespace context during admission and audit. Since then, 3.23.0-rc.1 added status resource routing for remote cluster mode, and 3.24.0-beta.0 made generated ValidatingAdmissionPolicy output deterministic to stop a reconcile loop.
◆ Where it's heading
The centre of gravity is moving from the admission controller to the tooling around it. Policies are becoming artefacts you install from a library at a version, benchmark against a baseline in CI, and test before they reach a cluster — which is the lifecycle application code already has and policy generally has not. Underneath, the ValidatingAdmissionPolicy path keeps maturing as Gatekeeper hands more enforcement to the Kubernetes-native mechanism it now generates.
◆ Prediction
Remote cluster mode gained status routing but the entries describe only that piece, so how far multi-cluster enforcement extends is unclear from these notes. The releases in this window are all beta and release candidates, so a 3.24.0 stable is the near-term milestone.
Alternatives to Firecracker and Gatekeeper
Other Infra & APIs products tracked by Sparkpulse, ranked by recent ship velocity. Each card links to a full editorial trajectory and lets you pivot into a head-to-head comparison with either Firecracker or Gatekeeper.
LibreSpeed
After a two-year redesign, LibreSpeed is adding tests instead of polishing pixels.
Nautobot
A security advisory cycle forced Nautobot to break its REST API on both supported branches at once.
GoCD
GoCD's changelog is one maintainer keeping a 2010s CI server running on current runtimes.
Incus
Incus settled its 7.0 LTS, then went straight back to a monthly feature cadence.
runc
runc now publishes an end-of-life calendar, and three branches shipped the same CVE fix in two days.
See all Firecracker alternatives → · See all Gatekeeper alternatives →
Recent activity from Firecracker and Gatekeeper
Latest ship moves from both products, interleaved chronologically. ⚡ = editorial spark.
- 24d agoGatekeeperDeterministic VAP generation stops a reconcile loop
- 1mo agoFirecrackerVsock timeout after snapshot restore, and jailer symlink revert
- 1mo agoGatekeeperStatus routing for remote cluster mode; mutation ApplyTo operations
- 2mo agoFirecrackerFirecracker v1.16.0 ⚡
- 4mo agoFirecrackervirtio-rng entropy cap and PCI transport hardening (CVE-2026-5747)
- 4mo agoFirecrackerCVE-2026-5747 hardening on the 1.15 branch
- 4mo agoGatekeeperCI and dependency updates only
- 4mo agoFirecrackerTCP SYN options length validation with MMDS enabled
- 5mo agoFirecrackerVMClock device and Intel Granite Rapids support
- 5mo agoGatekeepergator policy and gator bench: policy as an installable, benchmarked artefact ⚡
Frequently asked questions
What is the difference between Firecracker and Gatekeeper?
They serve adjacent needs but don't currently overlap on shipped themes. Gatekeeper is currently shipping more aggressively (velocity 2.5 vs 0.0), with 0 editorial sparks in the last 30 days against 0. See the at-a-glance table above for a side-by-side breakdown of velocity, recent sparks, and editorial themes.
Is Firecracker better than Gatekeeper?
Sparkpulse doesn't pick a winner — we score release velocity, not feature parity. Gatekeeper is currently shipping more aggressively (velocity 2.5 vs 0.0), with 0 editorial sparks in the last 30 days against 0. For your specific use case, the alternatives sections above list other Infra & APIs products to evaluate alongside.
What are the best alternatives to Firecracker?
Top Firecracker alternatives in Infra & APIs are ranked by recent ship velocity. Browse the "Firecracker alternatives" section above for the current picks, or visit /alternatives/firecracker for the full list with editorial commentary on each.
What are the best alternatives to Gatekeeper?
Top Gatekeeper alternatives in Infra & APIs are ranked by recent ship velocity. Browse the "Gatekeeper alternatives" section above for the current picks, or visit /alternatives/gatekeeper for the full list with editorial commentary on each.