Buoyant, the company behind Linkerd, has released Kinference, an open source project for building inference platforms on Kubernetes. Kinference is an inference control plane for Kubernetes and vLLM. It sits in front of a fleet of vLLM workers and decides where each request goes. It applies routing policies, token rate limits, KV-cache-aware load balancing and per-tenant metrics in one layer. For dev teams serving many open-weight models to many internal clients, it targets the layer above the model server. The project is Apache 2.0 licensed on GitHub. The current release is v0.1.0-alpha.7.
TL;DR
- Size: v0.1.0-alpha.7, written in Rust, Apache 2.0, configured through 5 Kubernetes CRDs.
- Runs on: any GPU-enabled Kubernetes cluster running vLLM. Buoyant’s benchmark used 3 L40S GPUs per pool.
- Performance: large gains on prefix-heavy traffic versus plain Kubernetes Service routing (self-reported).
- Best: median TTFT fell from 6.88 s to 0.31 s (95%) on a shared-prefix workload.
- Worst: no median TTFT gain on prompts without shared prefixes (6.92 s vs 6.83 s).
What is Kinference?
Kinference is a policy-driven control plane that turns Kubernetes plus vLLM into a multi-tenant inference platform. Buoyant’s FAQ puts it simply: vLLM is the data plane and Kinference is the control plane.
How does Kinference work?
The system has 2 parts: a traffic gateway and an inference handler. The GitHub README states that the handler exposes a gRPC interface. It takes a request and returns the chosen endpoint plus a possibly mutated body. It pairs with a proxy such as the Buoyant Gateway.
Kinference watches vLLM KV-cache events and engine metrics. It currently uses NVIDIA’s dynamo-kv-router crate to process cache events. Configuration lives in 5 CRDs: GatewayBackend, InferencePolicy, InferencePool, InferenceProvider and InferenceWorkerSet.
What are inference policies?
Inference policies are declarative rules for how each request is routed or rejected. Rules can match on tenant, requested model, GPU pool state and semantic tags. Example policies on the project site cover 5 patterns:
- Simple to cheaper: route low-complexity prompts to a smaller model, unless cache overlap makes the large model faster.
- Burst to cloud: skip workers with over 2 queued prompts, then fall back to providers like Bedrock.
- PII stays local: remove external providers when a PII tag fires, and fail closed with
onEmpty: Reject. - Batch on idle GPUs: send batch requests only to workers under 70% KV-cache usage.
- Model aliasing: publish one stable name, such as
standard-model, backed by several models.
Most rules end with minimize: PredictedTTFT. Kinference predicts time-to-first-token for each candidate endpoint, using cache overlap and queue length. Policies live in git and can be validated offline with the kinfctl CLI.
