How to delpoy a private DNS server in kubernetes

Fileshare setup for persist DNS record

Run this command in shell. These commands will create a fileshare to store DNS records and bind configuration.

AKS_PERS_STORAGE_ACCOUNT_NAME=mystorageaccount$RANDOM
AKS_PERS_RESOURCE_GROUP=test
AKS_PERS_LOCATION=japaneast
AKS_PERS_SHARE_NAME=named
# Create a resource group
az group create --name $AKS_PERS_RESOURCE_GROUP --location $AKS_PERS_LOCATION
# Create a storage account
az storage account create -n $AKS_PERS_STORAGE_ACCOUNT_NAME -g $AKS_PERS_RESOURCE_GROUP -l $AKS_PERS_LOCATION --sku Standard_LRS
# Export the connection string as an environment variable, this is used when creating the Azure file share
export AZURE_STORAGE_CONNECTION_STRING=$(az storage account show-connection-string -n $AKS_PERS_STORAGE_ACCOUNT_NAME -g $AKS_PERS_RESOURCE_GROUP -o tsv)
# Create the file share
az storage share create -n $AKS_PERS_SHARE_NAME --connection-string $AZURE_STORAGE_CONNECTION_STRING
# Get storage account key
STORAGE_KEY=$(az storage account keys list --resource-group $AKS_PERS_RESOURCE_GROUP --account-name $AKS_PERS_STORAGE_ACCOUNT_NAME --query "[0].value" -o tsv)
# Echo storage account name and key
echo Storage account name: $AKS_PERS_STORAGE_ACCOUNT_NAME
echo Storage account key: $STORAGE_KEY

create a secret to store the storage account key and name.

kubectl create secret generic bind-storage --from-literal=azurestorageaccountname=$AKS_PERS_STORAGE_ACCOUNT_NAME --from-literal=azurestorageaccountkey=$STORAGE_KEY

Deploy bind in AKS

Please apply below yaml in kubernetes, it will create an internal DNS service and an external DNS web service for manage. The bind-svc service will provide DNS service, the bind-web service is for managing. You may change bind-svc and bind-svc-tcp to internal loadbalancer if you want to provide internal DNS service.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: bind
spec:
  replicas: 1
  selector:
    matchLabels:
      app: bind
  template:
    metadata:
      labels:
        app: bind
    spec:
      nodeSelector:
        "beta.kubernetes.io/os": linux
      containers:
      - name: bind
        image: sameersbn/bind:9.16.1-20200524
        ports:
        - containerPort: 53
          containerPort: 10000
        volumeMounts:
        - name: dnsrecords
          mountPath: /data
      volumes:
      - name: dnsrecords
        azureFile:
          secretName: bind-storage
          shareName: named
          readOnly: false
---
apiVersion: v1
kind: Service
metadata:
  name: bind-svc
spec:
  type: LoadBalancer
  ports:
  - name: udp
    protocol: UDP
    port: 53
    targetPort: 53
  selector:
    app: bind
---
apiVersion: v1
kind: Service
metadata:
  name: bind-svc-tcp
spec:
  type: LoadBalancer
  ports:
  - name: tcp
    protocol: TCP
    port: 53
    targetPort: 53
  selector:
    app: bind
---
apiVersion: v1
kind: Service
metadata:
  name: bind-web
spec:
  type: LoadBalancer
  ports:
  - port: 10000
    targetPort: 10000
  selector:
    app: bind

Afterward, you can get services.

$ kubectl get svc
NAME           TYPE           CLUSTER-IP     EXTERNAL-IP    PORT(S)           AGE
bind-svc       LoadBalancer   10.0.189.133   20.48.82.100   53:31136/UDP      26s
bind-svc-tcp   LoadBalancer   10.0.123.178   20.48.82.68    53:31668/TCP      52s
bind-web       LoadBalancer   10.0.41.16     20.43.88.60    10000:31030/TCP   9d
kubernetes     ClusterIP      10.0.0.1       <none>         443/TCP           21d

Login https://20.43.88.60:10000, use default admin account(username: root, password: password)

Go to Servers->BIND DNS server, you can create your DNS zone here, and add DNS record.

Add DNS record to thisisatest.com zone.

Afterward, you will need to restart the named service. You can directly delete the bind pod. Or navigate to System -> bootup and shutdown, to restart the named(it will also trigger the pod restart).

You can setup the DNS to 10.0.163.91 internally for testing. You may change the service in bind.yaml to expose the DNS server if you want. I will create a pod within the cluster.

$ kubectl run -it test1 --image=centos -- bash
[root@test1 /]# cat /etc/resolv.conf
nameserver 20.48.82.100
search default.svc.cluster.local svc.cluster.local cluster.local reddog.microsoft.com
[root@test1 /]# nslookup page1.thisisatest.com
Server:         20.48.82.100
Address:        20.48.82.100#53
Name:   page1.thisisatest.com
Address: 120.120.120.120