kube32 Launches: Kubernetes-Compatible Runtime for ESP32 Microcontrollers

kube32

kube32 is a Kubernetes-compatible control plane and WebAssembly pod runtime for ESP32-S3 microcontrollers.

kubectl and k9s manage a cluster of boards over Wi-Fi or USB serial. Pods are WebAssembly modules executed by the wasm3 interpreter. One firmware image runs on every board. A board with PSRAM acts as the control plane and runs a local kubelet, while boards without PSRAM join as workers. The same sources build kube32-sim, a host simulator for macOS and Linux.

Features

• Kubernetes API serving Pod, Node, Namespace, Service, Endpoints, EndpointSlice, Ingress, Deployment, DaemonSet, Job, ConfigMap, Secret, Lease, Event, and metrics for kubectl and k9s, including watch streams, Table output, OpenAPI v3 validation, and log tailing.
• WebAssembly pods in wasm3 with SDKs and templates for Rust, C, and AssemblyScript, using either a request-handler ABI with k32_handle or an entry-point ABI with app_main, plus configurable memory limits and per-call gas budgets.
• Service routing, HTTP Ingress with host and prefix rules, Server-Sent Events streams, embedded static asset bundles via k32_resp_asset and StaticBundle, and synchronous pod-to-pod HTTP calls via k32_http_call.
• Persistent object store backed by a CRC-checked journal on a raw flash partition or the microSD card, plus persistentVolumeClaim pod volumes via k32_fs_* and rotated container logs for kubectl logs --previous.
• Peripheral access gated per pod by a capability firewall covering GPIO pins, ADC channels, I2C and UART buses, ST7789 display, key matrix, I2S speaker, and microSD storage.
• Container lifecycle management with restartPolicy set to Always, OnFailure, or Never, exponential CrashLoopBackOff, and distinct exit codes for Wasm traps, gas exhaustion, and OOMKilled.
• Optional bearer-token authentication and automatic self-signed ECDSA P-256 TLS on port 6443.
• Firmware rollouts through the cluster: one node at a time, SHA-256 checked, with bootloader rollback when an image does not come up healthy.
• Pub/sub events via k32_event_emit and kube32.io/event-topics, bridged across nodes over ESP-NOW and UDP port 7400.
• Multi-node host simulator kube32-sim and kube32-cli for building, checking, and deploying pods over the network or to node storage.

Hardware

See docs/hardware-spec.md for pin assignments and memory budgets.

Quick start

Simulator

Build and start a two-node cluster on macOS or Linux:

cmake -S . -B build && cmake --build build -j8
./build/kube32-sim --ingress-port 8080 --pod-port 17000

In a second terminal, configure kubectl and deploy the echo example:

export KUBECONFIG=$PWD/build/kubeconfig
kubectl config set-cluster kube32-sim --server=http://127.0.0.1:6443
kubectl config set-context kube32-sim --cluster=kube32-sim
kubectl config use-context kube32-sim
kubectl get nodes
kubectl apply -f examples/echo.yaml

Boards

Build and flash the firmware to each board with PlatformIO:

pio run -e esp32s3
bash scripts/flash.sh <serial-port> 921600

Open the serial console at 115200 baud and provision Wi-Fi and the board profile:

K32_CMD:BOARD:cardputer          # Cardputer worker only
K32_CMD:WIFI:<ssid>:<password>   # both boards
K32_CMD:AP:off                   # control plane
K32_CMD:API:<control-plane-ip>   # worker

Point kubectl at the control plane IP and apply a manifest:

kubectl config set-cluster kube32 --server=http://<control-plane-ip>:6443
kubectl config set-context kube32 --cluster=kube32
kubectl config use-context kube32
kubectl get nodes
kubectl apply -f examples/echo.yaml

See docs/quickstart.md for full setup instructions and TLS configuration.

Example: Tessera

Tessera is an issue tracker made of four WebAssembly pods routed by an Ingress. tessera-web and tessera-api run on the control plane to serve the web UI and in-memory search index. tessera-db and tessera-hud run on the Cardputer worker to persist records to an append-only log on the microSD card and drive the LCD and keypad (tessera-hud is silent by default; sound is opt-in via HUD_SOUND=1 and the speaker capability).

Generate the sample dataset, upload it to the worker's microSD card, and deploy:

make -C apps/tessera dataset
tools/kube32-cli push apps/tessera/build/card/kube32/volumes/tessera-db --node <worker-node> --path volumes/tessera-db
kubectl apply -f examples/tessera.yaml

Open http://<control-plane-ip>/ or http://127.0.0.1:8080/ on the simulator, and sign in as mara with password demo.

Documentation

Full documentation is published at https://arterialist.github.io/kube32/.

• Quick start
• Hardware specification
• Flashing and the serial console
• Writing app pods
• Cluster access and authentication
• Services, Ingress and pod-to-pod calls
• Storage and volumes
• Peripherals
• Example: Tessera
• Architecture overview
• Kubernetes API coverage
• CLI and tools reference

Contributing

Contributions are welcome. Read CONTRIBUTING.md for build instructions, test suites, and coding guidelines, or open an issue on GitHub.

Security

See SECURITY.md for the deployment security model and instructions on reporting vulnerabilities privately.