DNS not working with Kubernetes PetSet - docker

Question

Ok, following the examples and documentation on the Kubernetes website along with extensive research on Google, I still cannot get DNS resolution between the containers within my Pod.
I have a Service and a PetSet with 2 containers defined. When I deploy the PetSet and Service, they start and run successfully, but if I attempt to ping the host of one of my containers from the other by hostname or by the full domain name I get destination unreachable. I can ping by IP address though.
Here is my Kubernetes configuration file:
apiVersion: v1
kind: Service
metadata:
name: ml-service
labels:
app: marklogic
annotations:
service.alpha.kubernetes.io/tolerate-unready-endpoints: "true"
spec:
#restartPolicy: OnFailure
clusterIP: None
selector:
app: marklogic
ports:
- protocol: TCP
port: 7997
#nodePort: 31997
name: ml7997
- protocol: TCP
port: 8000
#nodePort: 32000
name: ml8000
# ... More ports defined
#type: NodePort
---
apiVersion: apps/v1alpha1
kind: PetSet
metadata:
name: marklogic
spec:
serviceName: "ml-service"
replicas: 2
template:
metadata:
labels:
app: marklogic
annotations:
pod.alpha.kubernetes.io/initialized: "true"
spec:
terminationGracePeriodSeconds: 30
containers:
- name: 'marklogic'
image: "{local docker registry ip}:5000/dcgs-sof/ml8-docker-final:v1"
imagePullPolicy: Always
command: ["/opt/entry-point.sh", "-l", "/opt/mlconfig.sh"]
ports:
- containerPort: 7997
name: ml7997
- containerPort: 8000
name: ml8000
- containerPort: 8001
name: ml8001
- containerPort: 8002
name: ml8002
- containerPort: 8040
name: ml8040
- containerPort: 8041
name: ml8041
- containerPort: 8042
name: ml8042
- containerPort: 8050
name: ml8050
- containerPort: 8051
name: ml8051
- containerPort: 8060
name: ml8060
env:
- name: POD_IP
valueFrom:
fieldRef:
fieldPath: status.podIP
lifecycle:
preStop:
exec:
command: ["/etc/init.d/MarkLogic stop"]
volumeMounts:
- name: ml-data
mountPath: /data
volumeClaimTemplates:
- metadata:
name: ml-data
annotations:
volume.alpha.kubernetes.io/storage-class: anything
spec:
accessModes: [ "ReadWriteOnce" ]
resources:
requests:
storage: 1Gi
I commented out the type: NodePort definition as I thought that might be the culprit, but still no success.
Additionally, if I run docker#minikube:/$ docker exec b4d21c4bc065 /bin/bash -c 'nslookup marklogic-1.marklogic.default.svc.cluster.local' it cannot resolve the name.
What am I missing???

Answer 1

You are resolving the wrong domain name.
See http://kubernetes.io/docs/user-guide/petset/#network-identity
You should try to resolve:
marklogic-0.ml-service.default.svc.cluster.local
If everything is within the default namespace, the DNS name is:
<pod_name>.<svc_name>.default.svc.cluster.local