Category: Containers

Jamie Wick continues a series on SQL Server and Windows containers:

The docker build command sends the contents of the working directory, along with a dockerfile, to the Docker daemon, as a build context, to create the new image. A dockerfile is a plain text file that contains the name of a (base) image, along with a set of instructions for modifying the image. By default, the dockerfile is assumed to be in the root of the working directory, but a separate location can be specified using the -f parameter in the build command. Additionally, the -t parameter can be used to specify a repository and tag for the new image. Finally, the working directory can be specified using a Path or URL. In the example below, the current directory (.) is being used as the working directory (the docker build command is being run at the root level of the working directory).

Read on for examples.

I have a post showing how to turn a database in SQL Server into a Docker container:

Today, we’re going to go through the process of turning a database you’ve built into a Docker container. Before we get started, here are the expectations:

1. I want a fully running copy of SQL Server with whatever database I’m using, as well as key components installed.
2. I want this not to be on a persistent volume. In other words, when I destroy the container and create a new one from my image, I want to reset back to the original state. I’m using this for technical demos, where I want to be at the same starting point each time.
3. I want this to be as easy as possible for users of my container. I consider the use of a container here as not particularly noteworthy in and of itself, so the more time I make people think trying to set up my demo environment, the more likely it is that people will simply give up.

With that preamble aside, let’s get to work!

As a bonus, you can finally learn my real thoughts on medieval France. Fun story around that: a much longer time ago than I’m willing to admit, I played a Hundred Years War scenario in Civilization 2, and the one thing I remember from that scenario is killing the Dauphin. After that, the script spawned a new claimant to the throne, who immediately attacked my troops and died. And then the script spawned yet another new claimant, who met the same fate within a couple turns. And then a third. If I remember correctly, I ran France out of claimants to the throne by the end of it.

Rob Farley takes us through updating SQL Server when it lives in a container:

Now, the thing with running SQL in containers is that the concept of downloading a patch file doesn’t work in the same way. If it were regular Linux, the commands would be very simple, such as ‘sudo yum update mssql-server’ in RHEL. But Docker doesn’t quite work the same way, as reflected by the Microsoft documentation which mentions Docker for installing but not in the Update section.

Rob then explains the process. Containers are cattle, not pets. Just make sure your data files live outside the container before you blow it away…

Praveen Sripati takes us through the way that kubeadm handles authorization and authentication for Kubernetes processes:

In the above K8S cluster, the default user (kubernetes-admin) created during the cluster setup has admin privileges to the cluster. This time I was curious on how the authentication and authorization work in K8S for this user to have full access to the cluster. This will enable me to be create additional users with different privileges, authentication and authorization mechanisms. It took me some time to get my mind/thoughts around it, but it’s all interesting. This blog is all about the same.

Note that the cluster has been setup using kubeadm, for kops and other the below varies a little bit. And also, kubeadm cluster setup default used X509 certificates for authentication. Authentication Providers are not built into K8S and so has to be integrated with external systems like Google Accounts, Active Directory, LDAP etc.

Click through to see what Praveen learned in the process.