I’m trying to figure out how can i execute SQL commands on MSSQL server which running in kubernetes. I tride init container and postStart hook but cant seem to find an answer.
When im using PowerShell, with this command i can excecute SQL commands on the SQL server. But cant do that from the yaml pipeline itself. kubectl exec -it podname -- /opt/mssql-tools/bin/sqlcmd -S localhost -U username -P "password" -Q "SELECT @@VERSION;"

Using the yaml pipeline often gives this error:
Sqlcmd: Error: Microsoft ODBC Driver 17 for SQL Server : Login timeout expired.
Sqlcmd: Error: Microsoft ODBC Driver 17 for SQL Server : TCP Provider: Error code 0x2749.
Sqlcmd: Error: Microsoft ODBC Driver 17 for SQL Server : A network-related or instance-specific error has occurred while establishing a connection to SQL Server. Server is not found or not accessible. Check if instance name is correct and if SQL Server is configured to allow remote connections. For more information see SQL Server Books Online..

Yaml which start a simple SQL server:

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: ${LOWERASSET}
  labels:
    app: ${ASSET}
spec:
  replicas: 1
  serviceName: ${LOWERASSET}
  selector:
    matchLabels:
      app: ${ASSET}
  template:
    metadata:
      labels:
        app: ${ASSET}
    spec:
      securityContext:
        fsGroup: 10001
      containers:
        - name: ${LOWERASSET}
          image: ${IMAGE}
          securityContext:
            runAsUser: 10001
          resources:
            requests:
              cpu: "200m"
              memory: "2Gi"
            limits:
              cpu: "500m"
              memory: "4Gi"
          ports:
            - containerPort: 1433
              name: tcpsql
          env:
            - name: MSSQL_PID
              value: Developer
            - name: ACCEPT_EULA
              value: "Y"
            - name: ENABLE_HADR
              value: "1"
            - name: AGENT_ENABLED
              value: "1"
            - name: SA_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: secret
                  key: pwd
          volumeMounts:
            - name: ${LOWERASSET}
              mountPath: "/var/opt/mssql"
  volumeClaimTemplates:
    - metadata:
        name: ${LOWERASSET}
        labels:
          app: ${ASSET}
          backup: "${BACKUP}"
      spec:
        storageClassName: encrypted-standard
        accessModes:
          - ReadWriteOnce
        resources:
          requests:
            storage: 8Gi
---
kind: Service
apiVersion: v1
metadata:
  name: ${LOWERASSET}
  labels:
    app: ${ASSET}
spec:
  type: ClusterIP
  selector:
    app: ${ASSET}
  ports:
    - name: tcpsql
      protocol: TCP
      port: 1433

**Here is my latest try. **

apiVersion: v1
kind: ConfigMap
metadata:
  name: sql-init-script
  namespace: namespace
data:
  init.sql: |
    some sql code

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: sql-server
  namespace: namespace
  labels:
    app: sql-server
spec:
  replicas: 1
  selector:
    matchLabels:
      app: sql-server
  template:
    metadata:
      labels:
        app: sql-server
    spec:
      containers:
      - name: sql-server
        image: ${IMAGE}
        ports:
        - containerPort: 1433
        env:
        - name: ACCEPT_EULA
          value: "Y"
        - name: SA_PASSWORD
          valueFrom:
            secretKeyRef:
              name: secret
              key: pwd
        readinessProbe:
          exec:
            command:
            - /opt/mssql-tools/bin/sqlcmd
            - -Q
            - "SELECT 1"
          initialDelaySeconds: 30
          periodSeconds: 10

---
apiVersion: v1
kind: Service
metadata:
  name: sql-server
  namespace: namespace
spec:
  ports:
  - port: 1433
    targetPort: 1433
  selector:
    app: sql-server
  type: ClusterIP

---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: ${LOWERASSET}
  namespace: namespace
  labels:
    app: ${ASSET}
spec:
  replicas: 1
  serviceName: ${LOWERASSET}
  selector:
    matchLabels:
      app: ${ASSET}
  template:
    metadata:
      labels:
        app: ${ASSET}
    spec:
      securityContext:
        fsGroup: 10001
      initContainers:
      - name: init-sql
        image: ${IMAGE}
        resources:
          requests:
            cpu: "200m"
            memory: "2Gi"
          limits:
            cpu: "500m"
            memory: "4Gi"
        command:
          - /bin/bash
        args:
          - -c
          - |
            echo "Starting SQL Server readiness check"
            until /opt/mssql-tools/bin/sqlcmd -S localhost -U sa -P "$SA_PASSWORD" -Q "SELECT 1"; do
              echo "Waiting for SQL Server to be ready"
              sleep 5
            done
            echo "SQL Server is ready."
            /opt/mssql-tools/bin/sqlcmd -S localhost -U sa -P "$SA_PASSWORD" -i /mnt/init/init.sql
        env:
        - name: SA_PASSWORD
          valueFrom:
            secretKeyRef:
              name: sql-server
              key: pwd
        volumeMounts:
        - name: init-script
          mountPath: /mnt/init
      containers:
      - name: ${LOWERASSET}
        image: ${IMAGE}
        resources:
          requests:
            cpu: "200m"
            memory: "2Gi"
          limits:
            cpu: "500m"
            memory: "4Gi"
        ports:
        - containerPort: 1433
          name: tcpsql
        volumeMounts:
        - name: ${LOWERASSET}
          mountPath: "/var/opt/mssql"
      volumes:
      - name: init-script
        configMap:
          name: sql-init-script
  volumeClaimTemplates:
  - metadata:
      name: ${LOWERASSET}
      labels:
        app: ${ASSET}
        backup: "${BACKUP}"
    spec:
      storageClassName: encrypted-standard
      accessModes:
      - ReadWriteOnce
      resources:
        requests:
          storage: 8Gi

---
apiVersion: v1
kind: Service
metadata:
  name: ${LOWERASSET}
  namespace: namespace
  labels:
    app: ${ASSET}
spec:
  type: ClusterIP
  selector:
    app: ${ASSET}
  ports:
  - name: tcpsql
    protocol: TCP
    port: 1433

Tried initcontainer, postStart hook.

Both came with the error mentioned above