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Kong Ingress Controller
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Using Gateway Discovery

Prerequisites

This guide will use helm v3 to deploy Kong’s helm chart with Kong and Kong Ingress Controller.

With helm v3 installed we can run:

$ helm repo add kong https://charts.konghq.com
$ helm repo update

to get Kong’s chart in its latest version.

Most of what is covered by this guide refers to Kong’s helm chart options defined in gateway discovery section.

This guide will be also using stern for easy pod logs querying.

Installation

In order to use Gateway Discovery we need to deploy Kong Ingress Controller so that it knows where to find Kong Gateways deployed in the cluster.

Kong Ingress Controller

In order to make KIC aware of deployed Gateway(s) we need to provide the name of the Admin service as well as the Proxy service.

This is being derived from the helm release name. Let’s store it in a variable so that we can use it in helm installation steps:

$ export GATEWAY_RELEASE_NAME=gateway

As Kong Ingress Controller and Kong Gateway deployments are separate, you should enable TLS client verification for the Admin API service so that no one from inside the cluster can access it without a valid certificate. This can be done by setting ingressController.adminApi.tls.client.enabled option in the Helm chart to true. It will create a CA certificate and a CA-signed certificate for the client, and respective Kubernetes TLS Secrets for both.

The CA certificate secret’s name can be set with ingressController.adminApi.tls.client.caSecretName option. We will use that to have a static name for the CA certificate secret, so that we can refer to it in the Kong Gateway deployment.

Note: It is possible to provide your own certificates for client verification. ingressController.adminApi.tls.client.certProvided=true and ingressController.adminApi.tls.client.secretName can be used for that purpose, in the Kong Ingress Controller release, and admin.tls.client.secretName or admin.tls.client.caBundle in the Kong Gateway release. For more information, see the helm chart’s readme.

Now we’re ready to deploy controller’s helm release:

$ helm upgrade --install controller kong/kong -n kong --create-namespace \
  --set ingressController.enabled=true \
  --set ingressController.gatewayDiscovery.enabled=true \
  --set ingressController.gatewayDiscovery.adminApiService.name=${GATEWAY_RELEASE_NAME}-kong-admin \
  --set ingressController.adminApi.tls.client.enabled=true \
  --set ingressController.adminApi.tls.client.caSecretName=admin-api-ca-cert \
  --set deployment.kong.enabled=false \
  --set proxy.nameOverride=${GATEWAY_RELEASE_NAME}-kong-proxy \
  --set replicaCount=2

At this point you should be able to see a Kong Ingress Controller deployment with 2 replicas, waiting for Kong Gateway to be deployed:

$ kubectl get deployment -n kong
NAME              READY   UP-TO-DATE   AVAILABLE   AGE
controller-kong   0/2     2            2           1m

Kong Gateway

After enabling TLS client verification for the Admin API service, you need to provide a CA certificate to the Kong Gateway deployment. You can do that by setting admin.tls.client.secretName to the CA certificate Secret’s name, which was set in the Kong Ingress Controller deployment.

Now you can deploy Kong Gateway. In order to do that we can run:

$ helm upgrade --install gateway kong/kong -n kong --create-namespace \
  --set ingressController.enabled=false \
  --set admin.enabled=true \
  --set admin.type=ClusterIP \
  --set admin.clusterIP=None \
  --set admin.tls.client.secretName=admin-api-ca-cert \
  --set replicaCount=2

which will deploy Kong Gateway with 2 replicas, without Kong Ingress Controller.

Once installed, set an environment variable, $PROXY_IP with the External IP address of the gateway-kong-proxy service in kong namespace:

$ export PROXY_IP=$(kubectl get -o jsonpath="{.status.loadBalancer.ingress[0].ip}" service -n kong gateway-kong-proxy)

At this point you should be able to see both deployments ready:

$ kubectl get deployment -n kong
NAME              READY   UP-TO-DATE   AVAILABLE   AGE
controller-kong   2/2     2            2           1m
gateway-kong      2/2     2            2           1m

You can also access the proxy service now:

$ curl $PROXY_IP
{"message":"no Route matched with those values"}%

Scaling deployments

Both Kong Gateway’s and Kong Ingress Controller’s deployments can be scaled independently.

Additional replicas, will:

  • In case of the controller, stand by to take over when elected leader gets shut down.
  • In case of the gateway, share the traffic with the other gateways from the deployment.

We can test scaling those 2 deployments by invoking:

$ kubectl scale deployment -n kong gateway-kong --replicas 4
$ kubectl scale deployment -n kong controller-kong --replicas 3

At this point we should see 4 instances of gateway and 3 instances of controller:

$ kubectl get deployment -n kong
NAME              READY   UP-TO-DATE   AVAILABLE   AGE
controller-kong   3/3     3            3           5m
gateway-kong      4/4     4            4           5m

Testing configuration

In order to verify that the configuration is indeed sent to all the Gateways we can deploy a simple HTTP Service:

echo "
apiVersion: apps/v1
kind: Deployment
metadata:
  name: httpbin
  labels:
    app: httpbin
spec:
  selector:
    matchLabels:
      app: httpbin
  template:
    metadata:
      labels:
        app: httpbin
    spec:
      containers:
      - name: httpbin
        image: kong/httpbin:0.1.0
        ports:
        - containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
  labels:
    app: httpbin
  name: httpbin
spec:
  ports:
  - port: 80
    protocol: TCP
    targetPort: 80
  selector:
    app: httpbin
  type: ClusterIP
" | kubectl apply -f -

with an Ingress with an IngressClass:

echo "
apiVersion: networking.k8s.io/v1
kind: IngressClass
metadata:
  name: kong
spec:
  controller: ingress-controllers.konghq.com/kong
 ---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: echo
  annotations:
    konghq.com/strip-path: 'true'
spec:
  ingressClassName: kong
  rules:
  - host: kong.example
    http:
      paths:
      - path: /echo
        pathType: Prefix
        backend:
          service:
            name: httpbin
            port:
              number: 80
" | kubectl apply -f -

With those manifests applied we can observe controller logs for entries that indicate successful configuration of all the discovered Gateways:

$ stern -n kong -lapp=controller-kong --since 1m --include "synced configuration"
...
controller-kong-545d798874-q6h7m ingress-controller time="2023-03-02T15:11:42Z" level=info msg="successfully synced configuration to kong" kong_url="https://10.244.0.29:8444"
controller-kong-545d798874-q6h7m ingress-controller time="2023-03-02T15:11:42Z" level=info msg="successfully synced configuration to kong" kong_url="https://10.244.0.15:8444"
controller-kong-545d798874-q6h7m ingress-controller time="2023-03-02T15:11:42Z" level=info msg="successfully synced configuration to kong" kong_url="https://10.244.0.16:8444"
controller-kong-545d798874-q6h7m ingress-controller time="2023-03-02T15:11:42Z" level=info msg="successfully synced configuration to kong" kong_url="https://10.244.0.30:8444"

At this point we should be able to access the /echo endpoint from our htptbin service:

$ curl -i http://kong.example/echo --resolve kong.example:80:$PROXY_IP
<!DOCTYPE html>
<html lang="en">

<head>
...

Through the means of Kubernetes Service, the traffic is load balanced across all Gateway pods that back the proxy service.

After issuing several queries against that service we can see in Gateway logs that we’re hitting all Pods which proxy the traffic as configured (mark the first column that contains the pod name):

$ stern -n kong -lapp=gateway-kong --since 1m --include "/echo"
gateway-kong-5c98495ff7-rnq5c proxy 10.244.0.1 - - [02/Mar/2023:15:16:09 +0000] "GET /echo HTTP/1.1" 200 9593 "-" "curl/7.86.0"
gateway-kong-5c98495ff7-s6rcw proxy 10.244.0.1 - - [02/Mar/2023:15:16:09 +0000] "GET /echo HTTP/1.1" 200 9593 "-" "curl/7.86.0"
gateway-kong-5c98495ff7-fdmz4 proxy 10.244.0.1 - - [02/Mar/2023:15:16:09 +0000] "GET /echo HTTP/1.1" 200 9593 "-" "curl/7.86.0"
gateway-kong-5c98495ff7-hx77j proxy 10.244.0.1 - - [02/Mar/2023:15:16:10 +0000] "GET /echo HTTP/1.1" 200 9593 "-" "curl/7.86.0"
gateway-kong-5c98495ff7-s6rcw proxy 10.244.0.1 - - [02/Mar/2023:15:16:10 +0000] "GET /echo HTTP/1.1" 200 9593 "-" "curl/7.86.0"
gateway-kong-5c98495ff7-fdmz4 proxy 10.244.0.1 - - [02/Mar/2023:15:16:10 +0000] "GET /echo HTTP/1.1" 200 9593 "-" "curl/7.86.0"
gateway-kong-5c98495ff7-fdmz4 proxy 10.244.0.1 - - [02/Mar/2023:15:16:10 +0000] "GET /echo HTTP/1.1" 200 9593 "-" "curl/7.86.0"
gateway-kong-5c98495ff7-rnq5c proxy 10.244.0.1 - - [02/Mar/2023:15:16:11 +0000] "GET /echo HTTP/1.1" 200 9593 "-" "curl/7.86.0"
gateway-kong-5c98495ff7-fdmz4 proxy 10.244.0.1 - - [02/Mar/2023:15:16:11 +0000] "GET /echo HTTP/1.1" 200 9593 "-" "curl/7.86.0"
gateway-kong-5c98495ff7-hx77j proxy 10.244.0.1 - - [02/Mar/2023:15:16:12 +0000] "GET /echo HTTP/1.1" 200 9593 "-" "curl/7.86.0"
gateway-kong-5c98495ff7-hx77j proxy 10.244.0.1 - - [02/Mar/2023:15:16:12 +0000] "GET /echo HTTP/1.1" 200 9593 "-" "curl/7.86.0"