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Category: Containers

Persisting Data for SQL Server on Docker Swarm

Published 2023-08-24 by Kevin Feasel

Andrew Pruski saves the day, or at least the data:

In my last couple of blog posts (here and here) I talked about how to get SQL Server running in Docker Swarm. But there is one big (and show-stopping) issue that I have not covered. How do we persist data for SQL Server in Docker Swarm?

Docker Swarm, like Kubernetes, has no native method to persist data across nodes…so we need another option and one of the options available to us is Portworx.

So how can we use Portworx to persist SQL Server databases in the event of a node failure in Docker Swarm?

Read on to find out how.

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Secrets Management in Docker Swarm

Published 2023-08-02 by Kevin Feasel

Andrew Pruski has a secret:

In a previous post I went through how to run SQL Server in Docker Swarm and in this post I want to continue delving into the Docker Swarm platform by looking at secrets.

Like Kubernetes, Docker Swarm has functionality to store sensitive data in secrets. When running SQL Server in containers we usually have to manually type out the environment variable for the MSSQL_SA_PASSWORD which isn’t great if we want to store that code in a public repository so being able to obfuscate that password is great!

Read on for a failed first attempt, followed by analysis and then success.

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Deploying a SQL Server Container via go-sqlcmd

Published 2023-07-06 by Kevin Feasel

Jes Schultz builds a container:

In the past, you may have downloaded and installed SQL Server Developer Edition on your computer to test features, write queries, and have a sandbox. Do you want a more lightweight development environment that’s quicker to install and use? Enter Docker or Podman, sqlcmd, and SQL Server containers. 

Our modern sqlcmd gives you the capability to query your existing SQL Server and Azure SQL Database instances. It also introduces new features such as creating containers in one line of code, using an existing backup file to restore a database when the instance is created, and opening Azure Data Studio for data exploration in one command. Here is how you can do this end-to-end. 

Click through for the demo.

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Protecting Kubernetes Services

Published 2023-06-30 by Kevin Feasel

Boemo Mmopelwa gives us an idea of Kubernetes service types and how to secure them:

A Kubernetes service is a logical abstraction that enables communication between different components in Kubernetes. Services provide a consistent way to access and communicate with the application’s underlying components, regardless of where those components are located.

In Kubernetes the default type is ClusterIP. Services abstract a group of pods with the same functions. Services expose pods and clusters. Services are crucial for connecting the backend and front-end of your applications.

This is different from your containerized applications that you can deploy on Kubernetes

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Updating SQL Server Containers on Kubernetes

Published 2023-03-24 by Kevin Feasel

Amit Khandelwal rolls out some updates:

I’m sure you’ve thought about how to update SQL Server containers running on a Kubernetes cluster at some point. So, this blog attempts to answer the question. According to the Kubernetes documentation, there are two Update strategies for statefulset workloads. For your convenience, I’m quoting the summary below:

  1.  OnDelete update : When a StatefulSet’s .spec.updateStrategy.type is set to OnDelete, the StatefulSet controller will not automatically update the Pods in a StatefulSet. Users must manually delete Pods to cause the controller to create new Pods that reflect modifications made to a StatefulSet’s .spec.template.
  2. Rolling update : When a statefuleset’s .spec.updateStrategy.type is set to RollingUpdate, the StatefulSet controller will delete and recreate each Pod in the StatefulSet. It will proceed in the same order as Pod termination (from the largest ordinal to the smallest), updating each Pod one at a time. This is the default update strategy.

Read the whole thing to learn how these two strategies of updating containers work.

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Estimating and Managing Pod Spread in AKS

Published 2023-03-20 by Kevin Feasel

Joji Varghese talks pod distribution in Azure Kubernetes Service:

In Azure Kubernetes Service (AKS), the concept of pod spread is important to ensure that pods are distributed efficiently across nodes in a cluster. This helps to optimize resource utilization, increase application performance, and maintain high availability.

This article outlines a decision-making process for estimating the number of Pods running on an AKS cluster. We will look at pod distribution across designated node pools, distribution based on pod-to-pod dependencies and distribution where pod or node affinities are not specified. Finally, we explore the impact of pod spread on scaling using replicas and the role of the Horizontal Pod Autoscaler (HPA). We will close with a test run of all the above scenarios.

Read on for tips, as well as a few web tools, which you can use to estimate and control pod spread in AKS.

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RBAC with Kubernetes

Published 2023-03-15 by Kevin Feasel

Mercy Bassey locks down some containers:

Have you been searching for a way to manage your resources effectively in Kubernetes? Why not consider Kubernetes Role-Based Access Control (RBAC)? With Kubernetes RBAC, you can securely manage containers.

Kubernetes RBAC allows administrators like yourself to define roles with specific permissions to access resources in a Kubernetes cluster. And in this tutorial, you will learn how to create a user and define roles with specific permissions.

There are enough steps involved that I’d definitely want to manage this at the group level.

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Tips for AKS Storage Provisioning

Published 2023-03-13 by Kevin Feasel

Joji Varghese gives us a hand:

In an Azure Kubernetes (AKS) cluster, Pods can access physical storage resources such as disks or volumes using Persistent Volumes (PV). To use these resources, Pods need to make a Persistent Volume Claim (PVC), which requests a specific amount of storage from a storage class. This claim can then be matched to an available Persistent Volume. Azure offers several storage solutions that can be used to provision Persistent Volumes in an AKS cluster.

This article will provide real-world guidance on securely using Container Storage Interface (CSI) drivers to provision Azure File Shares and Azure Blob storage in an AKS cluster.

If you’re looking at setting up Azure Kubernetes Service, give this a review.

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