Free SQL Help for Devs, DBAs, and the Curious

SQL workloads, a necessary part of any database-driven application, are often run on dedicated servers or in the cloud. However, with the advent of containerization and orchestration technologies, running these workloads inside a Kubernetes cluster using Stateful Sets has become a feasible and attractive option. This post will focus on how to utilize Kubernetes Stateful Sets to run SQL workloads from different SQL technologies, including SQL Server 2012, SQL Server 2014, MySQL 5.6, DB2 10.5, and Azure SQL.

Kubernetes is an open-source system for automating the deployment, scaling, and management of containerized applications. Stateful Sets is a Kubernetes feature that manages the deployment and scaling of a set of Pods and provides guarantees about the ordering and uniqueness of these Pods. Unlike a Deployment, a Stateful Set maintains a sticky identity for each of their Pods, which is crucial for applications like databases that require stable network identifiers and persistent storage.

Let's start with SQL Server workload. SQL Server 2012 and 2014 can be containerized and run inside a Kubernetes cluster. The first step is to create a Docker image for the SQL Server. The image should include the SQL Server binaries and any scripts or data files your application needs. Once the image is ready, you can create a Stateful Set in Kubernetes to run the SQL Server workload.

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: sqlserver
spec:
  serviceName: "sqlserver"
  replicas: 3
  template:
    metadata:
      labels:
        app: sqlserver
    spec:
      containers:
      - name: sqlserver
        image: your-sqlserver-image:latest
        ports:
        - containerPort: 1433

Running MySQL 5.6 workload inside Kubernetes is similar. The Docker image for MySQL should include the MySQL binaries and the necessary scripts and data files. After the image is ready, you can create a Stateful Set in Kubernetes to run the MySQL workload.

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: mysql
spec:
  serviceName: "mysql"
  replicas: 3
  template:
    metadata:
      labels:
        app: mysql
    spec:
      containers:
      - name: mysql
        image: your-mysql-image:latest
        ports:
        - containerPort: 3306

In the case of DB2 10.5, the process is similar. The Docker image for DB2 should include the DB2 binaries and the necessary scripts and data files. Once the image is ready, you can create a Stateful Set in Kubernetes to run the DB2 workload.

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: db2
spec:
  serviceName: "db2"
  replicas: 3
  template:
    metadata:
      labels:
        app: db2
    spec:
      containers:
      - name: db2
        image: your-db2-image:latest
        ports:
        - containerPort: 50000

For Azure SQL, the process is slightly different. Azure SQL is a fully managed database service, which means that it runs on Azure and is not directly containerizable. However, you can still use Kubernetes to manage your Azure SQL workloads by using Kubernetes Service and Secret to manage the connection string to the Azure SQL database.

In conclusion, running SQL workloads inside Kubernetes with Stateful Sets can be a viable choice for managing your SQL workloads. However, it requires a deep understanding of both SQL and Kubernetes technologies. Moreover, it's important to remember that while Kubernetes provides many benefits, it also introduces additional complexity, and it may not be suitable for every use case. Always consider your specific needs and constraints when deciding where and how to run your SQL workloads.