kubernetes/contrib/mesos/docs/discovery.md

Discovery

DNS

kube-dns

kube-dns is a Kubernetes add-on that works out of the box with Kubernetes-Mesos. For details on usage see the implementation in the cluster/mesos/docker source tree. kube-dns provides records both for services and pods.

mesos-dns

NOTE: There is still no support for publishing Kubernetes services in mesos-dns.

mesos-dns communicates with the leading Mesos master to build a DNS record set that reflects the tasks running in a Mesos cluster as documented here: http://mesosphere.github.io/mesos-dns/docs/naming.html. As of Kubernetes-Mesos release v0.7.2 there is experimental support in the scheduler to populate a task's discovery-info field in order to generate alternative/more friendly record names in mesos-dns, for pods only.

To enable this feature, set --mesos-generate-task-discovery=true when launching the scheduler.

The following discovery-info fields may be set using labels (without a namespace prefix) or else k8s.mesosphere.io/discovery-XXX annotations:

• visibility: may be framework, external, or cluster (defaults to cluster)
• environment
• location
• name (this alters record set generation in mesos-dns)
• version

In the case where both a label as well as an annotation are supplied the value of the annotation is observed. The interpretation of value of the name label (and discovery-name annotation) is a special case: the generated Mesos discovery-info.name value will be ${name}.${pod-namespace}.pod; all other discovery-info values are passed through without modification.

Example 1: Use a name label on a pod template

apiVersion: v1
kind: ReplicationController
metadata:
  name: frontend
spec:
  replicas: 3
  template:
    metadata:
      labels:
        app: guestbook
        tier: frontend
        name: custom-name
    spec:
      containers:
      - name: php-redis
        image: gcr.io/google_samples/gb-frontend:v3
        resources:
          requests:
            cpu: 100m
            memory: 100Mi
        env:
        - name: GET_HOSTS_FROM
          value: dns
        ports:
        - containerPort: 80

Example 2: Use a discovery-name annotation on a pod template

apiVersion: v1
kind: ReplicationController
metadata:
  name: frontend
spec:
  replicas: 3
  template:
    metadata:
      labels:
        app: guestbook
        tier: frontend
      annotations:
        k8s.mesosphere.io/discovery-name: custom-name
    spec:
      containers:
      - name: php-redis
        image: gcr.io/google_samples/gb-frontend:v3
        resources:
          requests:
            cpu: 100m
            memory: 100Mi
        env:
        - name: GET_HOSTS_FROM
          value: dns
        ports:
        - containerPort: 80