Kubernetes Gateway API

To get traffic from outside your mesh inside it (North/South) with Kuma you can use a builtin gateway.

In the quickstart, traffic was only able to get in the mesh by port-forwarding to an instance of an app inside the mesh. In production, you typically set up a gateway to receive traffic external to the mesh. In this guide you will add a built-in gateway in front of the demo-app service and expose it publicly. We will deploy and configure Gateway using Kubernetes Gateway API.

Service graph of the demo app with a builtin gateway on front:

  2. flowchart LR
  3.   subgraph edge-gateway
  4.     gw0(/ :8080)
  5.   end
  6.   demo-app(demo-app :5000)
  7.   redis(redis :6379)
  8.   gw0 --> demo-app
  9.   demo-app --> redis

Prerequisites

  • Completed quickstart to set up a zone control plane with demo application

Install Gateway API CRDs

To install Gateway API please refer to official installation instruction.

You also need to manually install Kuma GatewayClass:

  1. echo "apiVersion: gateway.networking.k8s.io/v1
  2. kind: GatewayClass
  3. metadata:
  4.   name: kuma
  5. spec:
  6.   controllerName: gateways.kuma.io/controller" | kubectl apply -f -

At this moment, when you install Gateway API CRDs after installing Kuma control plane you need to restart it to start Gateway API controller. To do this run:

  1. kubectl rollout restart deployment kuma-control-plane -n kuma-system

Start a gateway

The Gateway resource represents the proxy instance that handles traffic for a set of Gateway API routes. You can create gateway with a single listener on port 8080 by running:

  1. echo "apiVersion: gateway.networking.k8s.io/v1
  2. kind: Gateway
  3. metadata:
  4.   name: kuma
  5.   namespace: kuma-demo
  6. spec:
  7.   gatewayClassName: kuma
  8.   listeners:
  9.    - name: proxy
  10.      port: 8080
  11.      protocol: HTTP" | kubectl apply -f -

The Kubernetes cluster needs to support LoadBalancer for this to work.

If you are running minikube you will want to open a tunnel with minikube tunnel -p mesh-zone.

You may not have support for LoadBalancer if you are running locally with kind or k3d. One option for kind is kubernetes-sigs/cloud-provider-kind.

You can now check if the gateway is running in the demo app kuma-demo namespace:

  1. kubectl get pods -n kuma-demo

Observe the gateway pod:

  1. NAME                       READY   STATUS    RESTARTS   AGE
  2. demo-app-d8d8bdb97-vhgc8   2/2     Running   0          5m
  3. kuma-cfcccf8c7-hlqz5       1/1     Running   0          20s
  4. redis-5484ddcc64-6gbbx     2/2     Running   0          5m

Retrieve the public URL for the gateway with:

  1. export PROXY_IP=$(kubectl get svc --namespace kuma-demo kuma -o jsonpath='{.status.loadBalancer.ingress[0].ip}')
  2. echo $PROXY_IP

Check the gateway is running:

  1. curl -v ${PROXY_IP}:8080

Which outputs:

  1. *   Trying 127.0.0.1:8080...
  2. * Connected to 35.226.116.24 (35.226.116.24) port 8080
  3. > GET / HTTP/1.1
  4. > Host: 127.0.0.1:8080
  5. > User-Agent: curl/8.7.1
  6. > Accept: */*
  7. >
  8. * Request completely sent off
  9. < HTTP/1.1 404 Not Found
  10. < content-length: 62
  11. < content-type: text/plain
  12. < vary: Accept-Encoding
  13. < date: Mon, 04 Nov 2024 13:21:07 GMT
  14. < server: Kuma Gateway
  15. <
  16. This is a Kuma MeshGateway. No routes match this MeshGateway!
  17. * Connection #0 to host 35.226.116.24 left intact

Notice the gateway says that there are no routes configured.

Define a route using HTTPRoute

HTTPRoute resources contain a set of matching criteria for HTTP requests and upstream Services to route those requests to.

  1. echo "apiVersion: gateway.networking.k8s.io/v1
  2. kind: HTTPRoute
  3. metadata:
  4.   name: echo
  5.   namespace: kuma-demo
  6. spec:
  7.   parentRefs:
  8.     - group: gateway.networking.k8s.io
  9.       kind: Gateway
  10.       name: kuma
  11.       namespace: kuma-demo
  12.   rules:
  13.     - backendRefs:
  14.       - kind: Service
  15.         name: demo-app
  16.         port: 5000
  17.         weight: 1
  18.       matches:
  19.         - path:
  20.             type: PathPrefix
  21.             value: /" | kubectl apply -f -

Now try to reach our gateway again:

  1. curl -v ${PROXY_IP}:8080

which outputs:

  1. *   Trying 127.0.0.1:8080...
  2. * Connected to 127.0.0.1 (127.0.0.1) port 8080
  3. > GET / HTTP/1.1
  4. > Host: 127.0.0.1:8080
  5. > User-Agent: curl/8.4.0
  6. > Accept: */*
  7. >
  8. < HTTP/1.1 403 Forbidden
  9. < content-length: 19
  10. < content-type: text/plain
  11. < date: Fri, 09 Feb 2024 10:10:16 GMT
  12. < server: Kuma Gateway
  13. < x-envoy-upstream-service-time: 24
  14. <
  15. * Connection #0 to host 127.0.0.1 left intact
  16. RBAC: access denied%

Notice the forbidden error. This is because the quickstart has very restrictive permissions as defaults. Therefore, the gateway doesn’t have permissions to talk to the demo-app service.

To fix this, add a MeshTrafficPermission:

  1. echo "apiVersion: kuma.io/v1alpha1
  2. kind: MeshTrafficPermission
  3. metadata:
  4.   namespace: kuma-demo 
  5.   name: allow-gateway
  6. spec:
  7.   targetRef:
  8.     kind: MeshSubset
  9.     tags:
  10.       app: demo-app
  11.   from:
  12.     - targetRef:
  13.         kind: MeshSubset
  14.         tags: 
  15.           kuma.io/service: kuma_kuma-demo_svc 
  16.       default:
  17.         action: Allow" | kubectl apply -f -

Check it works with:

  1. curl -XPOST -v ${PROXY_IP}:8080/increment

Now it returns a 200 OK response:

  1. *   Trying 127.0.0.1:8080...
  2. * Connected to 127.0.0.1 (127.0.0.1) port 8080
  3. > POST /increment HTTP/1.1
  4. > Host: 127.0.0.1:8080
  5. > User-Agent: curl/8.4.0
  6. > Accept: */*
  7. >
  8. < HTTP/1.1 200 OK
  9. < x-powered-by: Express
  10. < content-type: application/json; charset=utf-8
  11. < content-length: 42
  12. < etag: W/"2a-gDIArbqhTz783Hls/ysnTwRRsmQ"
  13. < date: Fri, 09 Feb 2024 10:24:33 GMT
  14. < x-envoy-upstream-service-time: 6
  15. < server: Kuma Gateway
  16. <
  17. * Connection #0 to host 127.0.0.1 left intact
  18. {"counter":1,"zone":"local","err":null}

Securing your public endpoint with a certificate

The application is now exposed to a public endpoint thanks to the gateway. We will now add TLS to our endpoint.

Create a certificate

Create a self-signed certificate:

  1. openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout tls.key -out tls.crt -subj "/CN=${PROXY_IP}"

Create Kubernetes secret with generated certificate:

  1. echo "apiVersion: v1
  2. kind: Secret
  3. metadata:
  4.   name: my-gateway-certificate
  5.   namespace: kuma-demo
  6. type: kubernetes.io/tls
  7. data:
  8.   tls.crt: "$(cat tls.crt | base64)"
  9.   tls.key: "$(cat tls.key | base64)"" | kubectl apply -f -

Now update the gateway to use this certificate:

  1. echo "apiVersion: gateway.networking.k8s.io/v1
  2. kind: Gateway
  3. metadata:
  4.   name: kuma
  5.   namespace: kuma-demo
  6. spec:
  7.   gatewayClassName: kuma
  8.   listeners:
  9.     - name: proxy
  10.       port: 8080
  11.       protocol: HTTPS
  12.       tls:
  13.         certificateRefs:
  14.           - name: my-gateway-certificate" | kubectl apply -f -

Check the call to the gateway:

  1. curl -X POST -v --insecure "https://${PROXY_IP}:8080/increment"

Which should output a successful call and indicate TLS is being used:

  1. *   Trying 127.0.0.1:8080...
  2. * Connected to 127.0.0.1 (127.0.0.1) port 8080
  3. * ALPN: curl offers h2,http/1.1
  4. * (304) (OUT), TLS handshake, Client hello (1):
  5. * (304) (IN), TLS handshake, Server hello (2):
  6. * (304) (IN), TLS handshake, Unknown (8):
  7. * (304) (IN), TLS handshake, Certificate (11):
  8. * (304) (IN), TLS handshake, CERT verify (15):
  9. * (304) (IN), TLS handshake, Finished (20):
  10. * (304) (OUT), TLS handshake, Finished (20):
  11. * SSL connection using TLSv1.3 / AEAD-CHACHA20-POLY1305-SHA256
  12. * ALPN: server accepted h2
  13. * Server certificate:
  14. *  subject: CN=127.0.0.1
  15. *  start date: Feb  9 10:49:13 2024 GMT
  16. *  expire date: Feb  8 10:49:13 2025 GMT
  17. *  issuer: CN=127.0.0.1
  18. *  SSL certificate verify result: self signed certificate (18), continuing anyway.
  19. * using HTTP/2
  20. * [HTTP/2] [1] OPENED stream for https://127.0.0.1:8080/increment
  21. * [HTTP/2] [1] [:method: POST]
  22. * [HTTP/2] [1] [:scheme: https]
  23. * [HTTP/2] [1] [:authority: 127.0.0.1:8080]
  24. * [HTTP/2] [1] [:path: /increment]
  25. * [HTTP/2] [1] [user-agent: curl/8.4.0]
  26. * [HTTP/2] [1] [accept: */*]
  27. > POST /increment HTTP/2
  28. > Host: 127.0.0.1:8080
  29. > User-Agent: curl/8.4.0
  30. > Accept: */*
  31. >
  32. < HTTP/2 200
  33. < x-powered-by: Express
  34. < content-type: application/json; charset=utf-8
  35. < content-length: 42
  36. < etag: W/"2a-BZZq4nXMINsG8HLM31MxUPDwPXk"
  37. < date: Fri, 09 Feb 2024 13:41:11 GMT
  38. < x-envoy-upstream-service-time: 19
  39. < server: Kuma Gateway
  40. < strict-transport-security: max-age=31536000; includeSubDomains
  41. <
  42. * Connection #0 to host 127.0.0.1 left intact
  43. {"counter":5,"zone":"local","err":null}%

Note that we’re using --insecure as we have used a self-signed certificate.

Next steps