All articles tagged #arkade

Containers could have become a lightweight VM replacement. However, the most widely used form of containers, standardized by Docker/OCI, encourages you to have just one ~~process~~ service per container. Such an approach has a bunch of pros - increased isolation, simplified horizontal scaling, higher reusability, etc. However, there is a big con - in the wild, virtual (or physical) machines rarely run just one service.

While Docker tries to offer some workarounds to create multi-service containers, Kubernetes makes a bolder step and chooses a group of cohesive containers, called a Pod, as the smallest deployable unit.

When I stumbled upon Kubernetes a few years ago, my prior VM and bare-metal experience allowed me to get the idea of Pods pretty quickly. Or so thought I... 🙈

Starting working with Kubernetes, one of the first things you learn is that every pod gets a unique IP and hostname and that within a pod, containers can talk to each other via localhost. So, it's kinda obvious - a pod is like a tiny little server.

After a while, though, you realize that every container in a pod gets an isolated filesystem and that from inside one container, you don't see processes running in other containers of the same pod. Ok, fine! Maybe a pod is not a tiny little server but just a group of containers with a shared network stack.

But then you learn that containers in one pod can communicate via shared memory! So, probably the network namespace is not the only shared thing...

This last finding was the final straw for me. So, I decided to have a deep dive and see with my own eyes:

How Pods are implemented under the hood
What is the actual difference between a Pod and a Container
How one can create Pods using Docker.

And on the way, I hope it'll help me to solidify my Linux, Docker, and Kubernetes skills.

Disposable Local Development Environments with Vagrant, Docker, and Arkade

August 3, 2021 (Updated: June 5, 2022)

Programming,Ranting

I use a (rather oldish) MacBook for my day-to-day development tasks. But I prefer keeping my host operating system free of development stuff. This strategy has the following benefits:

Increasing reproducibility of my code - it often happened to me in the past that some code worked on my machine but didn't work on others; usually, it was due to missing dependencies. Developing multiple projects on the same machine makes it harder to track what libraries and packages are required for what project. So, now I always try to have an isolated environment per project.
Testing code on the target platform - most of my projects have something to do with server-side and infra stuff; hence the actual target platform is Linux. Since I use a MacBook, I spend a lot of time inside virtual machines running the same operating system as my servers do. So, I'd need to duplicate the development tools from my macOS on every Linux OS I happen to use.
Keeping the host operating system clean and slim - even if I work on something platform-agnostic like a command-line tool, I prefer not to pollute my workstation with the dev tools and packages anyway. Projects and domains change often, and installing all the required stuff right into the host operating system would make it messy real quick.
Decreasing time to recover in case of machine loss - a single multi-purpose machine quickly becomes a snowflake host. Coming up with the full list of things to reinstall in the case of a sudden machine loss would be hardly feasible.

Since I usually work on several projects at the same time, I need not one but many isolated development environments. And every environment should be project-tailored, easy to spin up, suspend, and, eventually, dispose. I figured a way to achieve that by using only a few tools installed on my host operating system, and I'm going to share it here.

The approach may be helpful for folks using macOS or Linux: