Containers

Yesterday in this post I described a method to correct permissions when upgrading a SQL Server 2017 container using Data Volumes to 2019’s non-root container on implementations that use the Moby or HyperKit VM. My friend Steve Jones’ on Twitter wondered if you could do this in one step by attaching a shell (bash) in the 2017 container prior to shutdown. Absolutely…let’s walk through that here in this post.  I opted to use an intermediate container in the prior post out of an abundance of caution so that I was not changing permissions on the SQL Server instance directory and all of the data files while they were in use. Technically this is a-ok, but again…just being paranoid there.

Recently Microsoft released a Non-Root SQL Server 2019 container and that’s the default if you’re pulling a new container image. But what if you’re using a 2017 container running as root and want to upgrade your system the SQL Server 2019 container…well something’s going to break. As you can see here, my friend Grant Fritchey came across this issue recently and asked for some help on Twitter’s #sqlhelp. This article describe a solution to getting things sorted and running again. The scenario below is if you’re using a Linux based SQL Server container on Windows or Mac host where the container volumes are backed by a Docker Moby or HyperKit virtual machine. If you’re using Linux container on Linux, you’ll adjust the file system permissions directly.

I’m very pleased to announce that I will be speaking at PASS Summit 2019!  This is my second time speaking at PASS Summit and I’m very excited to be doing so! What’s more, is I get to help blaze new ground with an emerging technology,** Kubernetes and how to run SQL Server in Kubernetes**!

My session is “Inside Kubernetes – An Architectural Deep Dive” if you’re a just getting started in the container space and want to learn how Kubernetes works and dive into how to deploy SQL Server in Kubernetes this is the session for you. I hope to see you there!

Let’s get you started on your Kubernetes journey with installing Kubernetes and creating a cluster in virtual machines.

Kubernetes is a distributed system, you will be creating a cluster which will have a master node that is in charge of all operations in your cluster. In this walkthrough we’ll create three workers which will run our applications. This cluster topology is, by no means, production ready. If you’re looking for production cluster builds check out Kubernetes documentation. [Here][1] and [here][2]. The primary components that need high availability in a Kubernetes cluster are the [API Server][3] which controls the state of the cluster and the [etcd][4] database which persists the state of the cluster. You can learn more about Kubernetes cluster components [here][5]. If you want to dive into Kubernetes more check out my Pluralsight Courses [here][6]! Where I have a dedicated course on [Installation and Configuration][7].

People often ask me what’s the number one thing to look out for when running SQL Server on Kubernetes…the answer is memory settings. In this post, we’re going to dig into why you need to configure resource limits in your SQL Server’s Pod Spec when running SQL Server workloads in Kubernetes. I’m running these demos in Azure Kubernetes Service (AKS), but these concepts apply to any SQL Server environment running in Kubernetes.

When working with SQL Server running containers the Error Log is written to standard out. Kubernetes will expose that information to you via kubectl. Let’s check out how it works.

If we start up a Pod running SQL Server and grab the Pod name

kubectl get pods
NAME                                READY   STATUS    RESTARTS   AGE
mssql-deployment-56d8dbb7b7-hrqwj   1/1     Running   0          22m

We can usefollow flag and that will continuously write the error log to your console, similar to using tail with the -f option. If you remove the follow flag it will write the current log to your console. This can be useful in debugging failed startups or in the case below, monitoring the status of a database restore. When finished you can use CTRL+C to break out and return back to your prompt.

      My new course **“Managing Kubernetes Controllers and Deployments”** in now available on Pluralsight <a href="https://www.pluralsight.com/courses/managing-kubernetes-controllers-deployments">here</a>! Check out the trailer <a href="https://www.pluralsight.com/player?name=82f986e5-de18-4897-a461-f1215db691ae&mode=live&clip=0&course=managing-kubernetes-controllers-deployments&author=anthony-nocentino">here</a> or if you want to dive right in go <a href="https://www.pluralsight.com/courses/managing-kubernetes-controllers-deployments">here</a>! This course offers practical tips from my experiences managing Kubernetes Clusters and workloads for Centino Systems clients.

      This course targets IT professionals that design and maintain Kubernetes and container based solutions.The course can be used by both the IT pro learning new skills and the system administrator or developer preparing for using Kubernetes both on premises and in the Cloud.

      Let’s take your Kubernetes administration and configuration skills to the next level and get you started <a href="https://www.pluralsight.com/courses/managing-kubernetes-controllers-deployments">now</a>!

      The modules of the course are:

    <ul>
      <li>
        **Using Controllers to Deploy Applications and Deployment Basics** – In this module we dive into what Controllers are and how they can be used to deploy applications in Kubernetes. We’ll introduce several core controller types and look at the fundamentals of using the `Deployment` Controller to deploy applications and take a deep dive into the Controller operations of `ReplicaSets`.
      </li>
      <li>
        **Maintaining Applications with Deployments** – In this demo-heavy module, we look closer at `Deployments` and learn how we can maintain our container based applications. We look at updating Deployments, controlling rollouts and using `u``pdateStrategy` and `readinessProbes` to ensure successful rollouts. We’ll also cover what to do when things go wrong and learn how to pause and rollback rollouts.
      </li>
      <li>
        **<a href="https://www.pluralsight.com/courses/managing-kubernetes-controllers-deployments">Deploying and Maintaining Applications with DaemonSets and Jobs</a>** – In this module, we introduce the `DaemonSet` controller and how it’s used to deploy applications to all Nodes or a subset of Nodes in our cluster, we’ll also cover `DaemonSet` operations such as updating and controlling rollouts. We wrap up the course with a look at how we can use `Jobs` and `CronJobs` to ensure work completes in our cluster.
      </li>
    </ul>

      <img loading="lazy" style="display: block; margin-left: auto; margin-right: auto;" title="NewImage.png" src="/images/2019/01/Availability-Group-StatusNewImage-3.png" alt="NewImage" width="565" height="128" border="0" />

      <a href="https://www.pluralsight.com/courses/managing-kubernetes-controllers-deployments">Check out the course at Pluralsight!</a>

Pre-conference Workshop at SQLSaturday Denver

I’m proud to announce that I will be be presenting an all day pre-conference workshop at SQL Saturday Denver on October 11th 2019! This one won’t let you down!

The workshop is **“Kubernetes Zero to Hero – Installation, Configuration, and Application Deployment” **

    <a href="https://www.eventbrite.com/e/kubernetes-zero-to-hero-installation-configuration-and-application-deployment-tickets-70529350185"><img loading="lazy" style="display: block; margin-left: auto; margin-right: auto;" title="NewImage.png" src="/images/2019/01/Availability-Group-StatusNewImage-1.png" alt="NewImage" width="129" height="126" border="0" /></a>

    **Here’s the abstract for the workshop**

  <blockquote>

      Modern application deployment needs to be fast and consistent to keep up with business objectives and Kubernetes is quickly becoming the standard for deploying container-based applications, fast. In this day-long session, we will start with an architectural overview of a Kubernetes cluster and how it manages application state. Then we will learn how to build a production-ready cluster. With our cluster up and running, we will learn how to interact with our cluster, common administrative tasks, then wrap up with how to deploy applications and SQL Server. At the end of the session, you will know how to set up a Kubernetes cluster, manage a cluster, deploy applications and databases, and how to keep everything up and running.

  </blockquote>

Session Objectives

So, if you’ve been following my blog you know my love for internals. Well, I needed to find out exactly how something worked at the startup of a SQL Server process running inside a docker container and my primary tool for this is <a href="http://man7.org/linux/man-pages/man1/strace.1.html">strace</a>, well how do you run strace against processes running in a container? I hadn’t done this before and needed to figure this out…so let’s go through how I pulled this off.

A quick post about pulling docker containers (this applies to docker run too)…when specifying the container image, the container image name and tag are case sensitive. We’re not going to discuss how much time troubleshooting it too me to figure this out…but let’s just say it’s more than I care to admit publicly.

In this code you can see I’m specifying the following image and tag server:2019-rc1-ubuntu (notice the lowercase rc in the tag)