<p>I am developing a simple web app with web service and persistent layer. Web persistent layer is Cockroach db. I am trying to deploy my app with single command:</p>
<pre><code>kubectl apply -f my-app.yaml
</code></pre>
<p>App is deployed successfully. However when backend has to store something in db the following error appears:</p>
<pre><code>dial tcp: lookup web-service-cockroach on 192.168.65.1:53: no such host
</code></pre>
<p>When I start my app I provide the following connection string to cockroach db and connection is successful but when I try to store something in db the above error appears:</p>
<pre><code>postgresql://root@web-service-db:26257/defaultdb?sslmode=disable
</code></pre>
<p>For some reason web pod can not talk with db pod. My whole configuration is:</p>
<pre><code>
# Service for web application
apiVersion: v1
kind: Service
metadata:
name: web-service
spec:
selector:
 app: web-service
type: NodePort
ports:
 - protocol: TCP
   port: 8080
   targetPort: http
   nodePort: 30103
externalIPs:
 - 192.168.1.9    # &lt; - my local ip
---

# Deployment of web app
apiVersion: apps/v1
kind: Deployment
metadata:
name: web-service
spec:
selector:
 matchLabels:
   app: web-service
replicas: 1
template:
 metadata:
   labels:
     app: web-service
 spec:
   hostNetwork: true
   containers:
     - name: web-service
       image: my-local-img:latest
       imagePullPolicy: IfNotPresent
       ports:
         - name: http
           containerPort: 8080
           hostPort: 8080
       env:
         - name: DB_CONNECT_STRING
           value: &quot;postgresql://root@web-service-db:26257/defaultdb?sslmode=disable&quot;

---
### Kubernetes official doc PersistentVolume
apiVersion: v1
kind: PersistentVolume
metadata:
name: cockroach-pv-volume
labels:
 type: local
spec:
storageClassName: manual
capacity:
 storage: 10Gi
accessModes:
 - ReadWriteOnce
hostPath:
 path: &quot;/tmp/my-local-volueme&quot;

---
### Kubernetes official doc PersistentVolumeClaim
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: cockroach-pv-claim
spec:
storageClassName: manual
accessModes:
 - ReadWriteOnce
resources:
 requests:
   storage: 4Gi
---

# Cockroach used by web-service
apiVersion: v1
kind: Service
metadata:
name: web-service-cockroach
labels:
 app: web-service-cockroach
spec:
selector:
 app: web-service-cockroach
type: NodePort
ports:
 - protocol: TCP
   port: 26257
   targetPort: 26257
   nodePort: 30104
---

# Cockroach stateful set used to deploy locally
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: web-service-cockroach
spec:
serviceName: web-service-cockroach
replicas: 1
selector:
 matchLabels:
   app: web-service-cockroach
template:
 metadata:
   labels:
     app: web-service-cockroach
 spec:
   volumes:
     - name: cockroach-pv-storage
       persistentVolumeClaim:
         claimName: cockroach-pv-claim
   containers:
     - name: web-service-cockroach
       image: cockroachdb/cockroach:latest
       command:
         - /cockroach/cockroach.sh
         - start
         - --insecure
       volumeMounts:
         - mountPath: &quot;/tmp/my-local-volume&quot;
           name: cockroach-pv-storage
       ports:
         - containerPort: 26257

</code></pre>
<p>After deployment everything looks good.</p>
<pre><code>kubectl get service
NAME                      TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)           AGE
kubernetes               ClusterIP   10.96.0.1      &lt;none&gt;        443/TCP           50m
web-service              NodePort    10.111.85.64   192.168.1.9   8080:30103/TCP    6m17s
webs-service-cockroach   NodePort    10.96.42.121   &lt;none&gt;        26257:30104/TCP   6m8s
</code></pre>
<pre><code>kubectl get pods
NAME                                  READY   STATUS    RESTARTS   AGE
web-service-6cc74b5f54-jlvd6   1/1     Running   0          24m
web-service-cockroach-0        1/1     Running   0          24m
</code></pre>
<p>Thanks in advance!</p>

user2739823
<p>Looks like you have a problem with DNS.</p>
<pre><code>dial tcp: lookup web-service-cockroach on 192.168.65.1:53: no such host
</code></pre>
<p>Address <code>192.168.65.1</code> does not like a kube-dns service ip.</p>
<p>This could be explaind if you where using host network, and surprisingly you do.
When using <code>hostNetwork: true</code>, the default dns server used is the server that the host uses and that never is a kube-dns.</p>
<hr />
<p>To solve it set:</p>
<pre><code>spec:
  dnsPolicy: ClusterFirstWithHostNet
</code></pre>
<p>It sets the dns server to the k8s one for the pod.</p>
<p>Have a look at kubernetes documentaion for more information about <a href="https://kubernetes.io/docs/concepts/services-networking/dns-pod-service/#pod-s-dns-policy" rel="nofollow noreferrer">Pod's DNS Policy</a>.</p>
