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Category: Containers

Persisting Databases with Docker Named Volumes

Published 2019-03-25 by Kevin Feasel

Andrew Pruski shows us how to use named volumes to keep containerized SQL Server databases hanging around:

The mssqluser named volume is going to be mounted as /var/opt/sqlserver and the mssqlsystem volume is going to be mounted as /var/opt/mssql. This is the key to the databases automatically being attached in the new container, /var/opt/mssql is the location of the system databases.

If we didn’t mount a named volume for the system databases any changes to those databases (particularly for the master database) would not be persisted so the new container would have no record of any user databases created.

Read the whole thing.

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SSIS on Windows Containers

Published 2019-03-18 by Kevin Feasel

Andy Leonard is a man who doesn’t like to take “no” for an answer:

Seriously, since I hopped the fence from developer to data I’ve dreamed of the day when I could practice lifecycle management with data-stuff like I used to practice lifecycle management with software development.
I recognize the obstacles. The greatest obstacle (in my humble opinion) is software is mostly stateless these days (these days started with Object-Oriented Programming and include its descendants).

Stateless development solves lots of engineering problems in lifecycle management, and by “solves a lot of engineering problems” I mean some engineering problems simply don’t exist so lifecycle management for stateless stuff can simply ignore a “lot of engineering problems.”

A database, on the other hand, is all about that state. When it comes to managing lifecycle for a stateful platform – like a database – ACID gets dumped on many lifecycle management tools and solutions (see what I did there?).

Is it possible to manage a data-related lifecycle using stateless tools? Yes. But here there be obstacles. Let’s look at on use case:

Click through for more thoughts and setup for a new series.

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Getting Started with Kubernetes

Published 2019-03-13 by Kevin Feasel

Praveen Sripati walks us through the Play with Kubernetes lab website:

There are many ways of installing K8S as mentioned here. It can be installed in the Cloud, on-premise and also locally on the laptop using virtualization. But, installing K8S had never been easy. In this blog, we will look at one of the easiest way to get started with K8S using Play with Kubernetes (PWK). With this the whole K8S experience is within the browser and there is nothing to install on the laptop, everything is installed on the remote machine. PWK uses ‘Docker in Docker’ which is detailed here (1, 2).

This looks like a really useful way to get the hang of Kubernetes before trying it out on your own machines.

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Deploying SQL Server Versions with Kubernetes

Published 2019-03-12 by Kevin Feasel

Anthony Nocentino shows how we can upgrade or even downgrade our SQL Server containers using Kubernetes deployment scripts:

There’s a few things I want to point out in our YAML file. First, we’re using a Deployment Controller. This will implement a Replica Set of the desired number of replicas using the container imaged defined. In this case, we’ll have 1 replica using the SQL Server 2017 CU11 Image. A Replica Set will guarantee that a defined set of Pods are running at any given time, here we’ll have exactly one Pod. We’re using a Deployment Controller, which gives us move between versions of Replica Sets based off different container images in a controlled fashion…more on that in a second.

Read the whole thing.

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Updating SQL Server on Linux Docker Images

Published 2019-03-11 by Kevin Feasel

Max Trinidad shows us how you can make a change to the default SQL Server container and save it for your own purposes:

The “docker commit …” command, you’ll provide both the image-name (all lowercase) and a TAG name (uppercase allowed). You can be creative in having an naming conversion for you images repositories.

It’s very important to save images after doing the commit. I found out that having an active container would be useless without an image.  As far as I know, I haven’t found a way to rebuild an image from an existing container if the image was previously removed.

Max has a full demo, including installing various tools and programs as well as tips on how to minimize the pain.

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Multi-Server Real-Time Scoring with R

Published 2019-03-05 by Kevin Feasel

David Smith points out a reference architecture for real-time scoring with R distributed through Kubernetes:

Let’s say you’ve developed a predictive model in R, and you want to embed predictions (scores) from that model into another application (like a mobile or Web app, or some automated service). If you expect a heavy load of requests, R running on a single server isn’t going to cut it: you’ll need some kind of distributed architecture with enough servers to handle the volume of requests in real time.

This reference architecture for real-time scoring with R, published in Microsoft Docs, describes a Kubernetes-based system to distribute the load to R sessions running in containers.

Looks interesting.

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Storing SQL Server Helm Charts in GitHub

Published 2019-02-28 by Kevin Feasel

Andrew Pruski shows how we can use GitHub to store Helm charts and access them easily:

In a previous post I ran through how to create a custom SQL Server Helm chart.

Now that the chart has been created, we need somewhere to store it.

We could keep it locally but what if we wanted to use our own Helm chart repository? That way we wouldn’t have to worry about deleting the chart on our local machine.

I use Github to store all my code to guard against accidentally deleting it (I’ve done that more than once) so why not use Github to store my Helm charts?

Cluster configurations are still code, and code belongs in source control.

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Issues From Using gMSA Accounts with Docker

Published 2019-02-28 by Kevin Feasel

Michal Poreba shares some lessons from trying to set up Docker and SQL Server to use gMSA accounts:

While in the end I was able to make it work on Windows Server 2016, 1803, 2019 and 1809 I wasted some time trying to make it work with docker 17.06. Unsuccessfully. Docker 18.09.1 and 18.09.2 worked every time.
There are some reports of intermittent problems with specific OS updates breaking stuff, like the one here but I wasn’t able to reproduce it. I wonder if the updates changes something else that it causing problems, in other words is it the problem with the update itself or the update process?

Read on for several helpful tips, as well as dead ends to avoid.

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.Net Core On Docker Connecting Via AD To SQL Server

Published 2019-02-22 by Kevin Feasel

Michal Poreba shows us how to connect Windows Docker containers running .Net Core to SQL Server via Active Directory when the containers are not connected to the domain:

The good news is that it is not an unreasonable requirement and it has been done before. The solution is to use Group Managed Service Accounts (gMSA) and Credential Spec Files. A number of people have already documented their efforts. Some were more successful than others.

Click through for a detailed guide to getting this working.

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