Shipping request events from kgateway over OpenTelemetry

git clone --depth 1 https://github.com/openmeterio/openmeter.git .openmeter
cd .openmeter/quickstart && docker compose up -d
# API comes up on http://localhost:48888

kind create cluster --config kind/cluster.yaml   # single node, name: kgw-metering

kubectl apply -f https://github.com/kubernetes-sigs/gateway-api/releases/download/v1.2.1/standard-install.yaml

helm upgrade -i kgateway-crds \
  oci://cr.kgateway.dev/kgateway-dev/charts/kgateway-crds --version v2.2.0 \
  -n kgateway-system --create-namespace --wait

helm upgrade -i kgateway \
  oci://cr.kgateway.dev/kgateway-dev/charts/kgateway --version v2.2.0 \
  -n kgateway-system --wait

apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: http
  namespace: kgateway-system
spec:
  gatewayClassName: kgateway
  listeners:
    - name: http
      protocol: HTTP
      port: 80
      allowedRoutes:
        namespaces: { from: All }
---
apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: echo
  namespace: demo
spec:
  parentRefs:
    - { name: http, namespace: kgateway-system }
  rules:
    - backendRefs:
        - { name: echo, port: 8080 }

apiVersion: gateway.kgateway.dev/v1alpha1
kind: ListenerPolicy
metadata:
  name: metering-accesslog
  namespace: kgateway-system
spec:
  targetRefs:
    - group: gateway.networking.k8s.io
      kind: Gateway
      name: http
  default:
    httpSettings:
      accessLog:
        - openTelemetry:
            grpcService:
              backendRef:
                kind: Service
                name: otlp-collector
                namespace: telemetry
                port: 4317
              logName: "kgateway-metering"
            body: "%REQ(:METHOD)% %REQ(:PATH)% %RESPONSE_CODE%"
            attributes:
              values:
                - { key: subject, value: { stringValue: "%REQ(X-CUSTOMER-ID)%" } }
                - { key: method,  value: { stringValue: "%REQ(:METHOD)%" } }
                - { key: route,   value: { stringValue: "%REQ(:PATH)%" } }
                - { key: status,  value: { stringValue: "%RESPONSE_CODE%" } }
                - { key: id,      value: { stringValue: "%REQ(X-REQUEST-ID)%" } }

helm upgrade -i opentelemetry-collector \
  oci://ghcr.io/openmeterio/helm-charts/benthos-collector --version 1.0.0-beta.229 \
  -n telemetry --create-namespace -f yaml/collector-values.yaml --wait

fullnameOverride: opentelemetry-collector
openmeter:
  url: http://host.docker.internal:48888
  token: "local-no-auth"
service:
  enabled: true
  port: 4317
config:
  input:
    otel_log:
      address: 0.0.0.0:4317
  pipeline:
    processors:
      - mapping: |
          root.id = this.record.attributes.id.or(uuid_v4())
          root.specversion = "1.0"
          root.type = "request"
          root.source = "kgateway"
          root.subject = this.record.attributes.subject.or("anonymous")
          root.data.method = this.record.attributes.method
          root.data.route  = this.record.attributes.route
          root.data.status = this.record.attributes.status
  output:
    openmeter:
      url: ${OPENMETER_URL:http://host.docker.internal:48888}
      token: ${OPENMETER_TOKEN:local-no-auth}

apiVersion: v1
kind: Service
metadata:
  name: otlp-collector
  namespace: telemetry
spec:
  selector:
    app.kubernetes.io/name: benthos-collector
  ports:
    - name: otlp-grpc
      port: 4317
      targetPort: 4317
      appProtocol: kubernetes.io/h2c
---
apiVersion: gateway.networking.k8s.io/v1beta1
kind: ReferenceGrant
metadata:
  name: allow-listenerpolicy-to-collector
  namespace: telemetry
spec:
  from:
    - group: gateway.kgateway.dev
      kind: ListenerPolicy
      namespace: kgateway-system
  to:
    - group: ""
      kind: Service

kubectl -n kgateway-system port-forward svc/http 8080:80 &

curl -s -H 'x-customer-id: tesco'      http://localhost:8080/products/99
curl -s -H 'x-customer-id: tesco'      http://localhost:8080/basket -X POST
curl -s -H 'x-customer-id: sainsburys' http://localhost:8080/products/12
curl -s -H 'x-customer-id: sainsburys' http://localhost:8080/checkout -X POST

# per-customer usage from OpenMeter
curl -s "http://localhost:48888/api/v1/meters/api_requests_total/query?groupBy=subject" | jq

apiVersion: gateway.kgateway.dev/v1alpha1
kind: GatewayExtension
metadata:
  name: jwt-metering
  namespace: kgateway-system
spec:
  jwt:
    providers:
      - name: metering-idp
        issuer: https://issuer.example.com
        audiences: ["metering"]
        jwks:
          inline: |
            { "keys": [ { "kty": "RSA", "kid": "metering", "use": "sig",
                          "n": "<modulus>", "e": "AQAB" } ] }
        claimsToHeaders:
          - name: sub                 # the verified JWT claim
            header: x-customer-id      # copied into the header the access log reads
---
apiVersion: gateway.kgateway.dev/v1alpha1
kind: TrafficPolicy
metadata:
  name: jwt-metering
  namespace: kgateway-system
spec:
  targetRefs:
    - group: gateway.networking.k8s.io
      kind: Gateway
      name: http
  jwtAuth:
    extensionRef:
      name: jwt-metering

kind delete cluster --name kgw-metering
cd .openmeter/quickstart && docker compose down -v