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Services and Routes

A Service inside Kubernetes is a way to abstract an application that is running on a set of Pods. This maps to two objects in Kong: Service and Upstream.

The service object in Kong holds the information of the protocol to use to talk to the upstream service and various other protocol specific settings. The Upstream object defines load-balancing and health-checking behavior.

 
flowchart LR
    H(Request traffic)
    subgraph Pods
        direction LR
        E(Target)
        F(Target)
        G(Target)
    end

    subgraph Kubernetes Service
        direction TB
        C(Service)
        D(Upstream)
    end
    
    subgraph Ingress rules
        direction LR
        A(Route)
        B(Route)
    end

    A --> C
    B --> C
    C --> D
    D --> E
    D --> F
    D --> G
    H --> A

    classDef lightBlue fill:#cce7ff;
    classDef lightGreen fill:#c4e1c4;
    classDef lightPurple fill:#e6d8eb;
    classDef lightGrey fill:#f5f5f5;

    class A,B lightGreen;
    class C lightBlue;
    class D lightPurple;
    class E,F,G lightGrey;

    linkStyle 6 stroke:#b6d7a8
  

Routes are configured using Gateway API or Ingress resources, such as HTTPRoute, TCPRoute, GRPCRoute, Ingress and more.

In this tutorial, you will deploy an echo service which returns information about the Kubernetes cluster and route traffic to the service.

Deploy an echo service

To proxy requests, you need an upstream application to send a request to. Deploying this echo server provides a simple application that returns information about the Pod it’s running in:

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

The results should look like this:

service/echo created
deployment.apps/echo created

Add routing configuration

Create routing configuration to proxy /echo requests to the echo server:

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: 1027
" | kubectl apply -f -

echo "
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: echo
  annotations:
    konghq.com/strip-path: 'true'
spec:
  ingressClassName: kong
  rules:
  - http:
      paths:
      - path: /echo
        pathType: ImplementationSpecific
        backend:
          service:
            name: echo
            port:
              number: 1027
" | kubectl apply -f -

The results should look like this:

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

ingress.networking.k8s.io/echo created

Test the routing rule:

curl -i $PROXY_IP/echo

The results should look like this:

HTTP/1.1 200 OK
Content-Type: text/plain; charset=utf-8
Content-Length: 140
Connection: keep-alive
Date: Fri, 21 Apr 2023 12:24:55 GMT
X-Kong-Upstream-Latency: 0
X-Kong-Proxy-Latency: 1
Via: kong/3.2.2

Welcome, you are connected to node docker-desktop.
Running on Pod echo-7f87468b8c-tzzv6.
In namespace default.
With IP address 10.1.0.237.
...

If everything is deployed correctly, you should see the above response. This verifies that Kong Gateway can correctly route traffic to an application running inside Kubernetes.