openova/platform/stunner

STUNner

K8s-native TURN/STUN for WebRTC NAT traversal. Application Blueprint (see docs/PLATFORM-TECH-STACK.md §4.5 — Communication). Used by bp-relay to make LiveKit (WebRTC SFU) reachable from clients behind NATs.

Status: Accepted | Updated: 2026-04-27

---

Overview

STUNner provides WebRTC connectivity:

• Kubernetes-native STUN/TURN server
• Gateway API integration
• Scalable media relay
• NAT traversal for video/audio

---

Architecture

flowchart TB
    subgraph External["External"]
        Client[WebRTC Client]
    end

    subgraph K8s["Kubernetes"]
        subgraph STUNner["STUNner"]
            GW[Gateway]
            TURN[TURN Servers]
        end

        subgraph Apps["Applications"]
            SFU[Media Server/SFU]
        end
    end

    Client -->|"STUN/TURN"| GW
    GW --> TURN
    TURN --> SFU
    Client -->|"Media"| TURN
    TURN -->|"Media"| SFU

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Why STUNner

Factor	STUNner	Traditional TURN
Deployment	Kubernetes-native	Separate VMs
Scaling	HPA/KEDA	Manual
Configuration	Gateway API CRDs	Config files
Integration	Native K8s	External

---

Configuration

Gateway

apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: stunner-gateway
  namespace: stunner
spec:
  gatewayClassName: stunner-gatewayclass
  listeners:
    - name: udp-listener
      port: 3478
      protocol: TURN-UDP
    - name: tcp-listener
      port: 3478
      protocol: TURN-TCP

UDPRoute

apiVersion: stunner.l7mp.io/v1
kind: UDPRoute
metadata:
  name: media-route
  namespace: stunner
spec:
  parentRefs:
    - name: stunner-gateway
  rules:
    - backendRefs:
        - name: media-server
          namespace: apps

GatewayConfig

apiVersion: stunner.l7mp.io/v1
kind: GatewayConfig
metadata:
  name: stunner-config
  namespace: stunner
spec:
  realm: stunner.<env>.<sovereign-domain>
  authType: longterm
  userName: stunner
  password:
    name: stunner-credentials
    namespace: stunner
    key: password

---

TURN Authentication

STUNner supports long-term credentials:

# Generate time-limited credentials
apiVersion: stunner.l7mp.io/v1
kind: GatewayConfig
spec:
  authType: longterm
  authLifetime: 86400  # 24 hours

---

Scaling

STUNner scales with KEDA based on connection count:

apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: stunner-scaler
  namespace: stunner
spec:
  scaleTargetRef:
    name: stunner
  minReplicaCount: 2
  maxReplicaCount: 10
  triggers:
    - type: prometheus
      metadata:
        serverAddress: http://mimir.monitoring.svc:8080/prometheus
        metricName: stunner_allocations_active
        query: sum(stunner_allocations_active)
        threshold: "100"

---

Monitoring

Metric	Description
stunner_allocations_active	Active TURN allocations
stunner_bytes_received_total	Received bytes
stunner_bytes_sent_total	Sent bytes
stunner_connections_total	Total connections

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