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Category: Containers

Managing Kubernetes Resources

Published 2019-04-04 by Kevin Feasel

Vincent-Philippe Lauzon takes us through some thoughts on Kubernetes resource allocation:

In this article we will look at how to inform Kubernetes about pods’ resources and how we can optimize for different scenarios.

A scenario that typically comes up is when a cluster has a bunch of pods where a lot of them are dormant, i.e. they don’t consume CPU or memory. Do we have to carve them a space they won’t use most of the time? The answer is no. As usual, it’s safer to provision capacity for a workload than relying on optimistic heuristic that not all workloads will require resources at the same time. So, we can configure Kubernetes optimistically or pessimistically.

Read the whole thing.

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Adding SSIS Catalog to a Docker Container

Published 2019-04-02 by Kevin Feasel

Andy Leonard takes two shots at adding the SSIS Catalog to a Docker container. First up is the version which doesn’t work:

I have been working on getting an SSIS Catalog running in a container for a couple years.
I share this post not to discourage you. 
I share it to let you know one way I failed. 
I thought I had succeeded when the PowerShell in this post worked. The PowerShell works, by the way – just not in a container configured thus.
This is but one failure. 
I failed more than once, I promise.

Andy perseveres and succeeds in part 4 of the series:

I can hear some of you thinking, “How do we accomplish this, Andy?”
I’m glad you asked. 
The answer is “We modify our container.”
Disclaimer: I’m about 100% certain there’s another way to do this and about 99% sure there’s a better way. I’m going to show you what I did. Cool?
Cool.

Read on to see how Andy did it.

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Persistent Disk Storage in Docker

Published 2019-04-01 by Kevin Feasel

Max Trinidad takes us through some of the basics of persistent disk storage in Docker:

Containers are perfectly suited for testing, meant to fast deployment of a solution, and can be easily deployed to the cloud. It’s cost effective!

Very important to understand! Containers disk data only exist while the container is running. If the container is removed, that data is gone.

So, you got to find the way to properly configure your container environment to make the data persist on disk.

Click through for an example.

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Persisting Databases with Docker Compose

Published 2019-03-28 by Kevin Feasel

Rob Sewell tries out docker-compose to persist databases using named volumes:

With all things containers I refer to my good friend Andrew Pruski. Known as dbafromthecold on twitter he blogs at https://dbafromthecold.com

I was reading his latest blog post Using docker named volumes to persist databases in SQL Server and decided to give it a try.

His instructions worked perfectly and I thought I would try them using a docker-compose file as I like the ease of spinning up containers with them.

Read on for Rob’s travails, followed by great success. And never go into something named “the spooky basement;” that’s just good life advice.

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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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