Spring Cloud Gateway Ingress Controller (Springress)

Springress is a minimal implementation of a Kubernetes Ingress Controller using Spring Cloud Gateway.

Currently it only supports very basic routing and the ingress type annotation must be set to spring.

There are two components to the project, the Spring Cloud Gateway application and a controller written in Go that converts ingress resources into a set of routes.

Components

Springress Controller

Written in Go it watches ingress resources and modifies a ConfigMap springress which contains a Spring Cloud Gateway config listing all of the routes for the gateway service to route for.

Springress Gateway

Written in Spring and taking advantage of Spring Cloud Kubernetes it automatically loads the config provided in the springress ConfigMap and routes for them.

Running

You'll find a Helm chart in helm/springress which you can use if you're so inclined, otherwise you can use the manifests found in examples.

Deploy Springress:

kubectl apply -f examples/springress.yaml

Check its running:

Note: the gateway can take up to 60 seconds to start

kubectl get pods
NAME                                    READY   STATUS    RESTARTS   AGE
springress-controller-75c75c654-dh9d6   1/1     Running   0          2m47s
springress-gateway-676c4657f4-gp25h     1/1     Running   0          2m47s

In a second terminal start a kubectl port-forard:

kubectl port-forward deployment/springress-gateway 9000:9000

Check the Gateway is responding:

$ curl localhost:9000
{"timestamp":1571508525936,"path":"/","status":404,"error":"Not Found","message":"No matching handler","requestId":"f3a3e68e"}

$ curl localhost:9000/actuator/health
{"status":"UP"}

Apply the foo/bar deployments and ingress:

kubectl apply -f examples/foo-bar-ingress.yaml

At this stage you can test that the controller picked up the Ingress resource:

$ kubectl logs --tail 10 deployment/springress-controller
W1019 18:05:04.700643       6 client_config.go:541] Neither --kubeconfig nor --master was specified.  Using the inClusterConfig.  This might not work.
I1019 18:05:04.705436       6 main.go:187] Starting Ingress controller
2019/10/19 18:05:04 annotation 'kubernetes.io/ingress.class' not set for spring
Sync/Add/Update for Ingress foo-bar
Created configmap "springress".

Validate that the configmap was created properly:

$ kubectl get configmap springress -o yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: springress
data:
  application.yaml: |
    spring:
      cloud:
        gateway:
          routes:
          - id: 2d4910e2-9fe6-4ea7-a0d1-56cf84e2fbec
            predicates:
            - Host=foo.com
            uri: http://foo:8080
          - id: b74df249-5e48-4705-a30b-b8915d7c9b45
            predicates:
            - Host=bar.com
            uri: http://bar:8080

Test the gateway is routing your applications correctly:

$ curl -H "Host: foo.com" localhost:9000
HELLO FOO
$ curl -H "Host: bar.com" localhost:9000
HELLO BAR