Trouble setting up service/route to connect to Kubernetes service using DNS name


#1

Hi,

I’m not able to set up a Kong service & route to connect to a Kubernetes service for a simple hello world application using the Kubernetes service DNS name i.e. (the Kong proxy cannot find the hello world application’s service when using the fully qualified name for the service).

I’d appreciate any assisting with my questions - thank you in advance.

1.) Am I using Kong correctly behind an Ingress ?
2.) Is the Kong Ingress Controller mature enough to be used instead in production ?
3.) What must I change in my Kong service/route definition to connect to my Kubernetes service ?

I am running Ubuntu 18.04 in a VirtualBox VM, using Canonical’s microk8s Kubernetes.

DNS and Ingress add-ons are both enabled.

chris@chris-VirtualBox:~$ microk8s.status
microk8s is running
addons:
gpu: disabled
storage: enabled
registry: enabled
ingress: enabled
dns: enabled
metrics-server: disabled
istio: disabled
dashboard: enabled

I’ve deployed :

  • Kong inside the Kubernetes cluser using the manifest deployment steps on the Kong website.

  • A simple hello world Spring boot application (An http request returns a “Greetings from Spring Boot!”). The application can be accessed on the service IP.

    chris@chris-VirtualBox:~$ curl --noproxy ‘*’ --url http://10.152.183.227:8087
    Greetings from Spring Boot!

  • An ingress allowing traffic through to the Kong proxy - my VM IP is 192.168.99.101.

    chris@chris-VirtualBox:~$ hostname -I
    10.0.2.15 192.168.99.101 172.17.0.1 10.1.1.1

  • I’ve configured a Kong service (name=spring-hello-world, protocol=http, host=10.152.183.277, port=8087) with a route (protocol=http, hosts=proxy.all, paths=/hello-world). The application can be accessed using the route.

    chris@chris-VirtualBox:~$ curl --noproxy ‘*’ --url http://192.168.99.101/hello-world --header ‘Host: proxy.all’
    Greetings from Spring Boot!

That’s all working fine, however I have a problem when trying to access the hello-world Kubernetes service based on its DNS name since I can’t rely on the IP being static.

  • To use the DNS name instead of IP, I configured another Kong service (name=spring-hello-world-service, protocol=http, host=spring-hello-world-service.default.svc.cluster.local, port=8087) with a route (protocol=http, hosts=proxy.all, paths=/hello-world-service). The application is not reachable.

    chris@chris-VirtualBox:~$ curl --noproxy ‘*’ --url http://192.168.99.101/hello-world-service --header ‘Host: proxy.all’
    {“timestamp”:“2018-12-16T09:51:50.680+0000”,“status”:404,“error”:“Not Found”,“message”:“No message available”,“path”:"/hello-world-service"}

  • nslookup to my Kubernetes hello-world-service works from another pod in the cluster, but not from within the Kong pods :

    chris@chris-VirtualBox:~$ kubectl exec -it curl-8564c8f987-mb74f – nslookup spring-hello-world-service.default.svc.cluster.local
    Server: 10.152.183.10
    Address 1: 10.152.183.10 kube-dns.kube-system.svc.cluster.local

    Name: spring-hello-world-service.default.svc.cluster.local
    Address 1: 10.152.183.227 spring-hello-world-service.default.svc.cluster.local

    chris@chris-VirtualBox:~$ kubectl exec -it kong-rc-5fdcfc9868-m747g – nslookup spring-hello-world-service.default.svc.cluster.local
    nslookup: can’t resolve ‘(null)’: Name does not resolve

    nslookup: can’t resolve ‘spring-hello-world-service.default.svc.cluster.local’: Try again
    command terminated with exit code 1

Contents of my Kubernetes cluster are below :

chris@chris-VirtualBox:~$ kubectl get all
NAME                                          READY   STATUS    RESTARTS   AGE
pod/busybox                                   0/1     Error     0          2d1h
pod/curl-8564c8f987-mb74f                     1/1     Running   2          44h
pod/default-http-backend-855bc7bc45-qxckp     1/1     Running   12         2d20h
pod/kong-rc-5fdcfc9868-m747g                  1/1     Running   14         3d10h
pod/kong-rc-5fdcfc9868-x5x6n                  1/1     Running   14         3d10h
pod/kong-rc-5fdcfc9868-z7rd6                  1/1     Running   14         3d10h
pod/nginx-ingress-microk8s-controller-zdjwn   1/1     Running   12         2d20h
pod/postgres-tbg6r                            1/1     Running   21         3d19h
pod/spring-hello-world-7968b9c669-d4959       1/1     Running   2          2d

NAME                             DESIRED   CURRENT   READY   AGE
replicationcontroller/postgres   1         1         1       3d19h

NAME                                 TYPE           CLUSTER-IP       EXTERNAL-IP   PORT(S)          AGE
service/default-http-backend         ClusterIP      10.152.183.82    <none>        80/TCP           2d20h
service/kong-admin                   LoadBalancer   10.152.183.13    <pending>     8001:31642/TCP   3d10h
service/kong-admin-ssl               LoadBalancer   10.152.183.194   <pending>     8444:31533/TCP   3d10h
service/kong-proxy                   LoadBalancer   10.152.183.146   <pending>     8000:32733/TCP   3d10h
service/kong-proxy-ssl               LoadBalancer   10.152.183.72    <pending>     8443:31738/TCP   3d10h
service/kubernetes                   ClusterIP      10.152.183.1     <none>        443/TCP          3d21h
service/postgres                     ClusterIP      10.152.183.168   <none>        5432/TCP         3d19h
service/spring-hello-world-service   LoadBalancer   10.152.183.227   <pending>     8087:30158/TCP   2d

NAME                                               DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR   AGE
daemonset.apps/nginx-ingress-microk8s-controller   1         1         1       1            1           <none>          2d20h

NAME                                   READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/curl                   1/1     1            1           44h
deployment.apps/default-http-backend   1/1     1            1           2d20h
deployment.apps/kong-rc                3/3     3            3           3d10h
deployment.apps/spring-hello-world     1/1     1            1           2d

NAME                                              DESIRED   CURRENT   READY   AGE
replicaset.apps/curl-8564c8f987                   1         1         1       44h
replicaset.apps/default-http-backend-855bc7bc45   1         1         1       2d20h
replicaset.apps/kong-rc-5fdcfc9868                3         3         3       3d10h
replicaset.apps/spring-hello-world-7968b9c669     1         1         1       2d

#2

Are you sure the above response is not from your Hello world service? I don’t recognize as a 404 from Kong.