feat(kafka): add local NVMe reference with repair DaemonSet

README.md

@@ -4,3 +4,4 @@ Reference architectures for various use cases at CoreWeave.
 ## Additional Reference Areas
 
 - [secrets-management](./secrets-management/README.md): Cloud KMS-backed secret manager patterns for Kubernetes workloads.
+- [kafka-local-nvme](./kafka-local-nvme/README.md): Strimzi Kafka reference for CoreWeave local NVMe, with opt-in local-PV repair.

kafka-local-nvme/.dockerignore

@@ -0,0 +1,2 @@
+.git
+tests

kafka-local-nvme/Dockerfile

@@ -0,0 +1,12 @@
+FROM golang:1.24-alpine AS build
+WORKDIR /src
+COPY go.mod ./
+RUN go mod download
+COPY cmd ./cmd
+COPY internal ./internal
+RUN CGO_ENABLED=0 go test ./...
+RUN CGO_ENABLED=0 go build -trimpath -ldflags='-s -w' -o /out/kafka-local-pv-repair ./cmd/kafka-local-pv-repair
+
+FROM gcr.io/distroless/static-debian12:nonroot
+COPY --from=build /out/kafka-local-pv-repair /kafka-local-pv-repair
+ENTRYPOINT ["/kafka-local-pv-repair"]

kafka-local-nvme/LICENSE

@@ -0,0 +1,203 @@
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kafka-local-nvme/README.md

@@ -0,0 +1,111 @@
+# Kafka on CoreWeave local NVMe
+
+<!-- customer-reference: entry-point -->
+[Customer reference architecture](docs/customer-reference-architecture.md)
+
+This non-production reference deploys Strimzi Kafka with dynamically provisioned, node-local storage below `/mnt/local/kafka`. It is a deployment starting point, not a production architecture, recovery procedure, or validation of CoreWeave availability, performance, or security.
+
+## Important storage limits
+
+`/mnt/local` is node-local storage. Treat its contents as lost when a node is lost or rebooted; Kubernetes PV/PVC identity does not make the underlying bytes durable.
+
+The `kafka-local` StorageClass uses `Retain` and the node pools use `deleteClaim: false`. Removing Kafka can therefore leave PVs, PVCs, and local data behind. Reusing the same namespace and Kafka resource names can reuse the same PVC-named directories; plan cleanup and identity changes deliberately.
+
+The provisioner creates directories and local PVs by running a Kubernetes helper Pod on the scheduled node. `WaitForFirstConsumer` ensures that node is selected first. Directory-backed local-path volumes can exceed their PVC request: requests neither reserve nor enforce `/mnt/local` capacity. Operators must independently verify available capacity and leave operational headroom on every selected node.
+
+## Profiles
+
+| Profile | Brokers | Controllers | Broker storage | Topic RF / min ISR |
+|---|---:|---:|---:|---:|
+| `two-node` | 2 | 3 | 400Gi each | 2 / 1 |
+| `five-node` | 5 | 3 | 400Gi each | 5 / 3 |
+
+Profiles are mutually exclusive and use the same resource names. The three controllers each request 20Gi.
+The five-node profile also enables Cruise Control and uses larger CPU and memory requests than the two-node profile.
+
+## Prerequisites
+
+- A Kubernetes cluster on CoreWeave, with `/mnt/local` available on every selected node.
+- `kubectl`, cluster-admin access for the local-path provisioner, and a Strimzi Cluster Operator configured to watch and reconcile the `kafka` namespace.
+- At least two or five nodes, respectively, labelled `kafka.local/kafka-local=true`.
+- Enough free node-local capacity for the requested claims and Kafka operational headroom.
+
+Install the Strimzi operator using its [official installation instructions](https://strimzi.io/docs/operators/latest/deploying.html) before applying a profile.
+
+## Deploy
+
+From this directory:
+
+```bash
+kubectl apply -k provisioner/local-path
+kubectl create namespace kafka --dry-run=client -o yaml | kubectl apply -f -
+kubectl label node NODE_NAME kafka.local/kafka-local=true
+kubectl apply -k profiles/two-node
+```
+
+Use `five-node` in the last command for the five-broker profile.
+
+Wait for the operator and Kafka resources to reconcile:
+
+```bash
+kubectl wait -n kafka --for=condition=Ready kafka/kafka-local --timeout=10m
+kubectl wait -n kafka --for=condition=Ready kafkatopic/kafka-local-topic --timeout=10m
+kubectl get kafka,kafkanodepool,kafkatopic,pvc -n kafka
+kubectl get pods -n kafka -o wide
+```
+
+Confirm that each PV is local and bound to the node chosen for its consuming Kafka Pod:
+
+```bash
+kubectl get pv -o custom-columns=NAME:.metadata.name,PATH:.spec.local.path,NODE:.spec.nodeAffinity.required.nodeSelectorTerms[0].matchExpressions[0].values[0],CLAIM_NAMESPACE:.spec.claimRef.namespace,CLAIM_NAME:.spec.claimRef.name
+```
+
+After Kafka and `kafka-local-topic` are Ready, run the basic producer/readback check:
+
+```bash
+./scripts/smoke-test.sh
+```
+
+It verifies exact readback of a small uniquely tagged message set produced with `acks=all`; it does not test node loss, reboot recovery, HA, performance, or security.
+
+## Optional Repair DaemonSet
+
+The normal Kustomizations do not install repair. The optional Repair DaemonSet only recreates absent directories in the exact managed hierarchy `/mnt/local/kafka/<namespace>/<claim>` after it verifies the host mount and an authorized, unchanged Node identity. It never restores lost bytes, deletes anything, or mutates PVs or PVCs. Kafka can rebuild only from healthy replicas; this is not automatic reboot, replacement, cleanup, or provider-behavior proof.
+
+Use it only during serialized operator maintenance:
+
+1. Build and publish the image, then use its immutable `repository@sha256:...` digest. The image build runs the Linux test suite before compiling the binary.
+
+   ```bash
+   docker build -t registry.example/kafka-local-pv-repair:VERSION .
+   docker push registry.example/kafka-local-pv-repair:VERSION
+   ```
+2. Capture each Node's exact `name`, hostname, Kubernetes UID, and nonempty provider ID in a tab-separated allowlist. Any identity difference requires explicit reauthorization and a newly rendered manifest.
+3. Independently verify the host `/mnt/local` mount filesystem, source, and canonical sorted comma-separated mount options; omit the `ro`/`rw` mode because the agent verifies that the host mount is writable itself.
+4. Render and apply the complete generated manifest (including ServiceAccount and RBAC). The renderer requires Python 3.
+
+   ```bash
+   ./scripts/render-kafka-local-pv-repair-manifest.sh \
+     --image registry.example/kafka-local-pv-repair@sha256:REPLACE_WITH_64_HEX \
+     --mount-fs ext4 --mount-source /dev/REPLACE_ME \
+     --mount-options nodev,nosuid \
+     --nodes nodes.tsv | kubectl apply -f -
+   ```
+
+5. Obtain the required Pod Security approval for `hostPID` and a read-write `/mnt/local` hostPath. The container runs as root only to create missing root-owned hierarchy components, with `CHOWN` and `DAC_OVERRIDE` as its only added capabilities. Check the DaemonSet rollout and logs, and serialize all related operator maintenance. A newly rendered authorization changes the Pod template and rolls the DaemonSet automatically.
+
+The two-node profile can lose controller quorum. Simultaneous local-storage loss can be unrecoverable even with the five-node profile.
+
+## Validate manifests
+
+```bash
+./scripts/validate.sh
+kubectl apply --dry-run=server -k provisioner/local-path
+kubectl apply --dry-run=server -k profiles/two-node
+```
+
+The server dry run is optional and requires a cluster with the Strimzi CRDs installed. Run it again with `profiles/five-node` when using that profile.
+
+## Package license
+
+This package is governed by [LICENSE](LICENSE) (Apache-2.0) and [THIRD_PARTY_NOTICES.md](THIRD_PARTY_NOTICES.md).

kafka-local-nvme/THIRD_PARTY_NOTICES.md

@@ -0,0 +1,13 @@
+# Third-party notices
+
+## Rancher Local Path Provisioner
+
+The manifests under `provisioner/local-path/` are derived from Rancher Local
+Path Provisioner version 0.0.36:
+
+<https://github.com/rancher/local-path-provisioner>
+
+Copyright 2014-2020 Rancher Labs, Inc.
+
+Rancher Local Path Provisioner is licensed under the Apache License, Version
+2.0. A copy of that license is included in this package as `LICENSE`.