cluster.local is hardcoded in dns names

[sbezverk]

Expected Behavior

k8s cluster dns name should be used as a suffix

Actual Behavior

cluster.local is hardcoded

Steps to Reproduce the Problem

On a kubernetes cluster with a non default domain name, kubernetes event sourcing is broken

{"level":"info","ts":1547132294.6397693,"logger":"fallback","caller":"kubernetesevents/adapter.go:93","msg":"Event delivery failed: %sPOST failed: Post http://testchannel-channel-s9krz.default.svc.cluster.local/: dial tcp: lookup testchannel-channel-s9krz.default.svc.cluster.local on 57.160.0.10:53: no such host","eventID":"df7aeafe-14e4-11e9-a85b-5254004c4249","sink":"http://testchannel-channel-s9krz.default.svc.cluster.local/"}

 kubectl get svc testchannel-channel-s9krz
NAME                        TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)   AGE
testchannel-channel-s9krz   ClusterIP   57.169.212.133   <none>        80/TCP    116m

[evankanderson]

How do you change the kubernetes cluster domain name? (So that we can test this if needed.)

[sbezverk]

@evankanderson when you bring up k8s cluster, there is an option to specify a custom domain. I use kubeadm to bring up cluster so it is stored here:

[root@kube-3 eventing]# kubectl get configmap -n kube-system kubeadm-config -o yaml
apiVersion: v1
data:
  ClusterConfiguration: |
    apiServer:
      extraArgs:
        authorization-mode: Node,RBAC
      timeoutForControlPlane: 4m0s
    apiVersion: kubeadm.k8s.io/v1beta1
    certificatesDir: /etc/kubernetes/pki
    clusterName: kubernetes
    controlPlaneEndpoint: ""
    controllerManager: {}
    dns:
      type: CoreDNS
    etcd:
      local:
        dataDir: /var/lib/etcd
    imageRepository: k8s.gcr.io
    kind: ClusterConfiguration
    kubernetesVersion: v1.13.0
    networking:
      dnsDomain: sbezverk.cisco.com . <===================
      podSubnet: 57.144.0.0/12
      serviceSubnet: 57.160.0.0/12
    scheduler: {}
  ClusterStatus: |
    apiEndpoints:
      kube-5.sbezverk.cisco.com:
        advertiseAddress: 192.168.80.105
        bindPort: 6443
    apiVersion: kubeadm.k8s.io/v1beta1
    kind: ClusterStatus
kind: ConfigMap
metadata:
  creationTimestamp: "2018-12-04T22:37:40Z"
  name: kubeadm-config
  namespace: kube-system
  resourceVersion: "176"
  selfLink: /api/v1/namespaces/kube-system/configmaps/kubeadm-config
  uid: 3560280f-f815-11e8-98d9-5254004c4249

Also here: /var/lib/kubelet/config.yaml

address: 0.0.0.0
apiVersion: kubelet.config.k8s.io/v1beta1
authentication:
  anonymous:
    enabled: false
  webhook:
    cacheTTL: 2m0s
    enabled: true
  x509:
    clientCAFile: /etc/kubernetes/pki/ca.crt
authorization:
  mode: Webhook
  webhook:
    cacheAuthorizedTTL: 5m0s
    cacheUnauthorizedTTL: 30s
cgroupDriver: cgroupfs
cgroupsPerQOS: true
clusterDNS:
- 57.160.0.10
clusterDomain: sbezverk.cisco.com . < ============