Gslb Ingress management and associated health checks

[ytsarev]

• Composite Ingress spec into Gslb spec from v1beta1
  Reuse Ingress spec type directly from v1beta1 api set

• Update status with managed hosts from Gslb Ingress rules
  Expose Gslb host list in status

• HealthCheck functions based on Service Endpoints
  Instead of directly checking Pods' Liveness and Readiness Probes
  we rely on EndpointsList of Service primitive, basically making
  k8s doing heavy lifting for us

And associated status update

[ytsarev]

Example CR spec and output

$ kubectl get gslb example-gslb -o yaml
apiVersion: ohmyglb.absa.oss/v1beta1
kind: Gslb
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"ohmyglb.absa.oss/v1beta1","kind":"Gslb","metadata":{"annotations":{},"name":"example-gslb","namespace":"default"},"spec":{"ingress":{"rules":[{"host":"app.cloud.absa.internal","http":{"paths":[{"backend":{"serviceName":"app","servicePort":"http"},"path":"/"}]}}]},"strategy":"roundRobin"}}
  creationTimestamp: "2019-12-09T23:14:28Z"
  generation: 2
  name: example-gslb
  namespace: default
  resourceVersion: "24978"
  selfLink: /apis/ohmyglb.absa.oss/v1beta1/namespaces/default/gslbs/example-gslb
  uid: 6b4d51cf-eb14-49d9-a4bc-35c8368ec7fe
spec:
  ingress:
    rules:
    - host: app.cloud.absa.internal
      http:
        paths:
        - backend:
            serviceName: app
            servicePort: http
          path: /
    - host: app.cloud.absa.external
      http:
        paths:
        - backend:
            serviceName: nginx
            servicePort: http
          path: /
  strategy: roundRobin
status:
  managedHosts:
  - app.cloud.absa.internal
  - app.cloud.absa.external
  serviceHealth:
    app: NotFound
    nginx: Healthy

$ kubectl describe gslb example-gslb
Name:         example-gslb
Namespace:    default
Labels:       <none>
Annotations:  kubectl.kubernetes.io/last-applied-configuration:
                {"apiVersion":"ohmyglb.absa.oss/v1beta1","kind":"Gslb","metadata":{"annotations":{},"name":"example-gslb","namespace":"default"},"spec":{"...
API Version:  ohmyglb.absa.oss/v1beta1
Kind:         Gslb
Metadata:
  Creation Timestamp:  2019-12-09T23:14:28Z
  Generation:          2
  Resource Version:    24978
  Self Link:           /apis/ohmyglb.absa.oss/v1beta1/namespaces/default/gslbs/example-gslb
  UID:                 6b4d51cf-eb14-49d9-a4bc-35c8368ec7fe
Spec:
  Ingress:
    Rules:
      Host:  app.cloud.absa.internal
      Http:
        Paths:
          Backend:
            Service Name:  app
            Service Port:  http
          Path:            /
      Host:                app.cloud.absa.external
      Http:
        Paths:
          Backend:
            Service Name:  nginx
            Service Port:  http
          Path:            /
  Strategy:                roundRobin
Status:
  Managed Hosts:
    app.cloud.absa.internal
    app.cloud.absa.external
  Service Health:
    App:    NotFound
    Nginx:  Healthy
Events:     <none>

[donovanmuller]

This is looking awesome 👍

HealthCheck functions based on Service Endpoints
Instead of directly checking Pods' Liveness and Readiness Probes
we rely on EndpointsList of Service primitive, basically making
k8s doing heavy lifting for us

💯that is what was intended, I.e. "k8s doing heavy lifting for us"

[donovanmuller]

I need to skill up on Go so can't offer too much in terms of review but from what I see it looks great 👍

[ytsarev]

@donovanmuller thanks a lot for review! Merging in.