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Deploy availability groups on Kubernetes with DH2i DxOperator on Azure Kubernetes Service

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Applies to: SQL Server - Linux

This tutorial explains how to configure SQL Server Always On availability groups (AGs) for SQL Server Linux based containers deployed to an Azure Kubernetes Service (AKS) Kubernetes cluster, using DH2i DxOperator. These procedures are also applicable to Azure Red Hat OpenShift clusters; the primary distinction is the deployment of an Azure Red Hat OpenShift cluster, followed by substituting kubectl commands with oc in the following steps.

Note

Microsoft supports data movement, AG, and SQL Server components. DH2i is responsible for support of the DxEnterprise product, which includes cluster and quorum management. DxOperator is a software extension to Kubernetes that uses custom resource definitions to automate the deployment of DxEnterprise clusters. DxEnterprise then provides all of the instrumentation to create, configure, manage and provide automatic failover for SQL Server AG workloads in Kubernetes.

You can register for a free DxEnterprise software license. For more information, see the DxOperator Quick Start Guide.

Using the steps mentioned in this article, learn how to deploy a StatefulSet and use the DH2i DxOperator to create and configure an AG with three replicas, hosted on AKS.

This tutorial consists of the following steps:

  • Create a configmap object on AKS cluster with mssql-conf settings
  • Install DxOperator
  • Create a secret objects
  • Deploy 3 replica SQL AG using YAML file
  • Connect to SQL Server

Prerequisites

  • An Azure Kubernetes Service (AKS) or Kubernetes cluster.

  • A valid DxEnterprise license with AG features and tunnels enabled. For more information, see the developer edition for nonproduction usage, or DxEnterprise software for production workloads.

Create the configmap object

  1. In AKS, create the configmap object, which has mssql-conf settings based on your requirements. In this example, you create the configMap, using a file called mssqlconfig.yaml with the following parameters.

    apiVersion: v1
kind: ConfigMap
metadata:
  name: mssql-config
data:
  mssql.conf: |
    [EULA]
    accepteula = Y

    [sqlagent]
    enabled = true

  2. Create the object by executing the following command.

    kubectl apply -f ./mssqlconfig.yaml

Create secret objects

Create a secret to store the sa password for SQL Server.

kubectl create secret generic mssql --from-literal=MSSQL_SA_PASSWORD="<password>"

Caution

Your password should follow the SQL Server default password policy. By default, the password must be at least eight characters long and contain characters from three of the following four sets: uppercase letters, lowercase letters, base-10 digits, and symbols. Passwords can be up to 128 characters long. Use passwords that are as long and complex as possible.

Create a secret to store the license key for DH2i. Visit DH2i's website to get a developer license. Replace XXXX-XXXX-XXXX-XXXX in the following example with your license key.

kubectl create secret generic dxe --from-literal=DX_PASSKEY="<password>" --from-literal=DX_LICENSE=XXXX-XXXX-XXXX-XXXX

Install DxOperator

To install DxOperator, you must download the DxOperator YAML file using the following example, and then apply the YAML file.

  1. Deploy the YAML describing how to set up an AG, using the following command. Save the file with a custom name, such as DxOperator.yaml.

    curl -L https://dxoperator.dh2i.com/dxesqlag/files/v1.yaml -o DxOperator.yaml
kubectl apply –f DxOperator.yaml

  2. After you install the operator you can deploy SQL Server containers, configure the availability group, define replicas, deploy and configure the DxEnterprise cluster. Here is a sample deployment YAML file called DxEnterpriseSqlAg.yaml, which you can change to suit your requirements.

    apiVersion: dh2i.com/v1
kind: DxEnterpriseSqlAg
metadata:
  name: contoso-sql
spec:
  synchronousReplicas: 3
  asynchronousReplicas: 0
  # ConfigurationOnlyReplicas are only allowed with availabilityGroupClusterType set to EXTERNAL
  configurationOnlyReplicas: 0
  availabilityGroupName: AG1
  # Listener port for the availability group (uncomment to apply)
  availabilityGroupListenerPort: 51433
  # For a contained availability group, add the option CONTAINED
  availabilityGroupOptions: null
  # Valid options are EXTERNAL (automatic failover) and NONE (no automatic failover)
  availabilityGroupClusterType: EXTERNAL
  createLoadBalancers: true
  template:
    metadata:
      labels:
        label: example
      annotations:
        annotation: example
    spec:
      dxEnterpriseContainer:
        image: "docker.io/dh2i/dxe:latest"
        imagePullPolicy: Always
        acceptEula: true
        clusterSecret: dxe
        vhostName: VHOST1
        joinExistingCluster: false
        # QoS – guaranteed (uncomment to apply)
        #resources:
          #limits:
            #memory: 1Gi
            #cpu: '1'
        # Configuration options for the required persistent volume claim for DxEnterprise
        volumeClaimConfiguration:
          storageClassName: null
          resources:
            requests:
              storage: 1Gi
      mssqlServerContainer:
        image: "mcr.microsoft.com/mssql/server:latest"
        imagePullPolicy: Always
        mssqlSecret: mssql
        acceptEula: true
        mssqlPID: Developer
        mssqlConfigMap: mssql-config
        # QoS – guaranteed (uncomment to apply)
        #resources:
          #limits:
            #memory: 2Gi
            #cpu: '2'
        # Configuration options for the required persistent volume claim for SQL Server
        volumeClaimConfiguration:
          storageClassName: null
          resources:
            requests:
              storage: 2Gi
      # Additional side-car containers, such as mssql-tools (uncomment to apply)
      #containers:
      #- name: mssql-tools
          #image: "mcr.microsoft.com/mssql-tools"
          #command: [ "/bin/sh" ]
          #args: [ "-c", "tail -f /dev/null" ]

  3. Deploy the DxEnterpriseSqlAg.yaml file.

    kubectl apply -f DxEnterpriseSqlAg.yaml

Create an availability group listener

Apply the following YAML to add a load balancer, by setting the selector to value of metadata.name in the previous step. In this example, it's contoso-sql.

apiVersion: v1
kind: Service
metadata:
  name: contoso-cluster-lb
spec:
  type: LoadBalancer
  selector:
    dh2i.com/entity: contoso-sql
  ports:
    - name: sql
      protocol: TCP
      port: 1433
      targetPort: 51444
    - name: listener
      protocol: TCP
      port: 51433
      targetPort: 51433
    - name: dxe
      protocol: TCP
      port: 7979
      targetPort: 7979

Verify the deployment and load balancer assignments.

kubectl get pods
kubectl get services

You should see output similar to the following example.

NAME                     TYPE           CLUSTER-IP   EXTERNAL-IP     PORT(S)                                         AGE
contoso-cluster-lb       LoadBalancer   10.1.0.21    172.212.20.29   1433:30484/TCP,14033:30694/TCP,7979:30385/TCP   3m18s
contoso-sql-0            ClusterIP      None         <none>          7979/TCP,7980/TCP,7981/UDP,5022/TCP,1433/TCP    79m
contoso-sql-0-lb         LoadBalancer   10.1.0.210   4.255.19.171    7979:32374/TCP,1433:32444/TCP                   79m
contoso-sql-1            ClusterIP      None         <none>          7979/TCP,7980/TCP,7981/UDP,5022/TCP,1433/TCP    79m
contoso-sql-1-lb         LoadBalancer   10.1.0.158   4.255.19.201    7979:30152/TCP,1433:30868/TCP                   79m
contoso-sql-2            ClusterIP      None         <none>          7979/TCP,7980/TCP,7981/UDP,5022/TCP,1433/TCP    79m
contoso-sql-2-lb         LoadBalancer   10.1.0.159   4.255.19.218    7979:30566/TCP,1433:31463/TCP                   79m
kubernetes               ClusterIP      10.1.0.1     <none>          443/TCP                                         87m

PS /home/aravind> kubectl get pods
NAME         READY   STATUS    RESTARTS   AGE
contoso-sql-0   2/2     Running   0          74m
contoso-sql-1   2/2     Running   0          74m
contoso-sql-2   2/2     Running   0          74m

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