All articles tagged #vm

Saim Safdar from the Cloud Native Islamabad community generously invited me to his channel to conduct a Kubernetes 101 workshop. However, as often happens, I found myself pulled in a slightly different direction:

What if you don't start with Pods, Deployments, and Services and instead take a step back and look at how things were done in the past with good old VMs? Can it help you understand Kubernetes faster and deeper?

Below, I present a more polished version of the workshop, enriched with illustrations and runnable examples. You can experiment with these examples directly in your browser on labs.iximiuz.com.

Read more

There are lots of posts trying to show how simple it is to get started with Kubernetes. But many of these posts use complicated Kubernetes jargon for that, so even those with some prior server-side knowledge might be bewildered. Let me try something different here. Instead of explaining one unfamiliar matter (how to run a web service in Kubernetes?) with another (you just need a manifest, with three sidecars and a bunch of gobbledygook), I'll try to reveal how Kubernetes is actually a natural development of the good old deployment techniques.

If you already know how to run services using virtual machines, hopefully, you'll see that there's not much of a difference in the end. And if you're totally new to operating services at scale, following through the evolution of the technology might help you as well with the understanding of contemporary approaches.

As usual, this article is not meant to be comprehensive. Rather it's an attempt to summarize my personal experience and how my understanding of the domain has been forming over the years.

Read more

There are many ways to create containers, especially on Linux and alike. Besides the super widespread Docker implementation, you may have heard about LXC, systemd-nspawn, or maybe even OpenVZ.

The general concept of the container is quite vague. What's true and what's not often depends on the context, but the context itself isn't always given explicitly. For instance, there is a common saying that containers are Linux processes or that containers aren't Virtual Machines. However, the first statement is just an oversimplified attempt to explain Linux containers. And the second statement simply isn't always true.

In this article, I'm not trying to review all possible ways of creating containers. Instead, the article is an analysis of the OCI Runtime Specification. The spec turned out to be an insightful read! For instance, it gives a definition of the standard container (and no, it's not a process) and sheds some light on when Virtual Machines can be considered containers.

Read more

Well, I don't see any practical applications of the approach I'm going to describe... However, I do think that messing about with things like this is the only way to gain extra knowledge of any system internals. We are going to speak Docker and Linux here. What if we want to take a base Docker image, I mean really base, just an image made with a single line Dockerfile like FROM debian:latest, and convert it to something launchable on a real or virtual machine? In other words, can we create a disk image having exactly the same Linux userland a running container has and then boot from it? For this we would start with dumping container's root file system, luckily it's as simple as just running docker export, however, to finally accomplish the task a bunch of additional steps is needed...

UPD: Seems like there is some practicality in the approach after all! 👉 github.com/linka-cloud/d2vm.

Read more