Multiple Backends

HTTPRoute supports adding multiple Services under its BackendRefs field. When you add multiple Services, requests through the HTTPRoute are distributed across the Services. This guide walks through creating an HTTPRoute with multiple backend Services.

Prerequisites: Install Kong Ingress Controller with Gateway API support in your Kubernetes cluster and connect to Kong.

Prerequisites

Install the Gateway APIs

1. Install the Gateway API CRDs before installing Kong Ingress Controller.

    kubectl apply -f https://github.com/kubernetes-sigs/gateway-api/releases/download/v1.1.0/standard-install.yaml
   

2. Create a Gateway and GatewayClass instance to use.

   echo "
   ---
   apiVersion: gateway.networking.k8s.io/v1
   kind: GatewayClass
   metadata:
     name: kong
     annotations:
       konghq.com/gatewayclass-unmanaged: 'true'
   
   spec:
     controllerName: konghq.com/kic-gateway-controller
   ---
   apiVersion: gateway.networking.k8s.io/v1
   kind: Gateway
   metadata:
     name: kong
   spec:
     gatewayClassName: kong
     listeners:
     - name: proxy
       port: 80
       protocol: HTTP
       allowedRoutes:
         namespaces:
            from: All
   " | kubectl apply -f -
   

   The results should look like this:

   gatewayclass.gateway.networking.k8s.io/kong created
   gateway.gateway.networking.k8s.io/kong created
   

Install Kong

You can install Kong in your Kubernetes cluster using Helm.

1. Add the Kong Helm charts:

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

2. Install Kong Ingress Controller and Kong Gateway with Helm:

    helm install kong kong/ingress -n kong --create-namespace 
   

Test connectivity to Kong

Kubernetes exposes the proxy through a Kubernetes service. Run the following commands to store the load balancer IP address in a variable named PROXY_IP:

1. Populate $PROXY_IP for future commands:

    export PROXY_IP=$(kubectl get svc --namespace kong kong-gateway-proxy -o jsonpath='{.status.loadBalancer.ingress[0].ip}')
    echo $PROXY_IP
   

2. Ensure that you can call the proxy IP:

    curl -i $PROXY_IP
   

   The results should look like this:

    HTTP/1.1 404 Not Found
    Content-Type: application/json; charset=utf-8
    Connection: keep-alive
    Content-Length: 48
    X-Kong-Response-Latency: 0
    Server: kong/3.0.0
     
    {"message":"no Route matched with those values"}
   

Deploy multiple Services with HTTPRoute

1. Deploy two echo Services so that you have multiple BackendRefs to use for traffic splitting:

    kubectl apply -f https://docs.konghq.com/assets/kubernetes-ingress-controller/examples/echo-services.yaml
   

   The results should look like this:

    service/echo created
    deployment.apps/echo created
    service/echo2 created
    deployment.apps/echo2 created
   

2. Deploy a HTTPRoute that sends traffic to both the services. By default, traffic is distributed evenly across all services:

   echo 'apiVersion: gateway.networking.k8s.io/v1
   kind: HTTPRoute
   metadata:
     name: echo
     annotations:
       konghq.com/strip-path: "true"
   spec:
     parentRefs:
     - name: kong
     rules:
     - matches:
       - path:
           type: PathPrefix
           value: /echo
       backendRefs:
       - name: echo
         kind: Service
         port: 80
       - name: echo2
         kind: Service
         port: 80
   ' | kubectl apply -f -
   

   The results should look like this:

    httproute.gateway.networking.k8s.io/echo created
   

3. Send multiple requests through this route and tabulating the results to check an even distribution of requests across the Services:

    curl -s "$PROXY_IP/echo/hostname?iteration="{1..200} -w "\n" | sort | uniq -c
   

   The results should look like this:

    100 echo2-7cb798f47-gv6hs
    100 echo-658c5ff5ff-tv275
   

Add Service weights

The weight field overrides the default distribution of requests across Services. Each Service instead receives weight / sum(all Service weights) percent of the requests.

1. Add weights to the Services in the HTTPRoute’s backend list.

    kubectl patch --type json httproute echo -p='[
        {
          "op":"add",
          "path":"/spec/rules/0/backendRefs/0/weight",
          "value":200
        },
        {
          "op":"add",
          "path":"/spec/rules/0/backendRefs/1/weight",
          "value":100
        }
    ]'
   

   The results should look like this:

    httproute.gateway.networking.k8s.io/echo patched
   

2. Send the same requests and roughly 1/3 of the requests go to echo2 and 2/3 going to echo:

    curl -s "$PROXY_IP/echo/hostname?iteration="{1..200} -w "\n" | sort | uniq -c
   

   The results should look like this:

     67 echo2-7cb798f47-gv6hs
    133 echo-658c5ff5ff-tv275