Today, I'd like to share with you a series of articles that I currently read. It's called "Let's code a TCP/IP stack" and it provides a very nice insight into the Linux networking stack. I'm still going through all the articles but I'm sharing all of them here:

1. Let's code a TCP/IP stack, 1: Ethernet & ARP
2. Let's code a TCP/IP stack, 2: IPv4 & ICMPv4
3. Let's code a TCP/IP stack, 3: TCP Basics & Handshake
4. Let's code a TCP/IP stack, 4: TCP Data Flow & Socket API
5. Let's code a TCP/IP stack, 5: TCP Retransmission

#networking

Videos from DevOps Days 2023 are available on YouTube now!

#slides

The latest episode of our voice chat (in Ukrainian) is now available!

We spoke about documentation: where to store it, how to write it and how to make people read it.

You can find it on:

- YouTube
- Substack
- Spotify
- Apple Podcasts
- Google Podcasts

Enjoy!

#voice #говорилка

A comparison between EKS and AKS.

Tors article provides some insights into what to expect from each managed service. It’s a pity, GKE is not included into this comparison, I’ve heard a lot of good things about GKE. I believe, this is because this article originated from a specific use-case.

#kubernetes #aws #azure

​​For today's Donations Monday, I'd like to remind you about the Protect the Sky fundraiser by Come Back Alive and Nova Posta.

This is a very important fundraiser that helps Ukrainian Air Defence units.

#donations #Ukraine

Programming Book Bundle by Packt.

I don’t know if you do programming day-to-day. Also, this channel is more OPS oriented, I would say.

However, you may find some interesting stuff there.

#programming #books

An interesting insight into Facebook's internal architecture. Basically, because of their size they could create a vast serverless platform for internal use that handles trillions of requests.

This article is a summary of a whitepaper published earlier. You can find this whitepaper in PDF format here. I haven't read it yet, though.

#serverless

There’s a new test functionality in Terraform v1.6.0.

You can read more about writing tests for your Terraform projects in this article, which also has examples of the tests.

For someone who values tests for IaC, I’m very glad that such functionality is a part of the core. Although, I haven’t been working much with Terraform lately, implementing tests for Helm charts yielded some great results. I hope to write an article in that one day.

P.S. This article was kindly sent right into my inbox by Terraform Weekly. Do not hesitate to subscribe, you’d like to get the latest news on the most popular IaC tool.

#terraform #hashicorp

A new issue of the CatOps Digest is here!

#digest

DOU, KOLO та «Шалені Кабани» збирають 5 млн грн на 4 Mini Sharks для «Альфи» СБУ 🦈🔥

БО «Шалені кабани» — ініціатива, яку добре знайома DevOps-спільноті. На літній офлайн-події для девопсів в Києві ми зібрали гроші на мотор для човнів морської піхоти, а пізніше — ще.

До речі, новини про висадку українських морпіхів на лівому березі Херсонщини мають безпосередній стосунок до човників, над якими працюють «Кабани».

Тож, коли ми готували спільний збір, не мали жодного сумніву, що девопси активно підтримають колег та задонатять на 4 Mini Shark для ЦСО «А» СБУ («Альфа»). Адже потрібно зібрати 5 000 000 грн!

Приєднуйтесь! 📌
Лінк для донатів 💵

AWS Karpenter is in beta now.

Karpenter is AWS’ tool to manage and autoscale node pools in Kubernetes, which has more features compared to the Cluster Autoscaler and has deeper integration with AWS features. Yet, support for other major clouds is somewhere in the roadmap, IIRC.

This article in particular, describes what are the changes in Karpenter Beta compared to the previous versions and also guides you through depreciations and upgrade notes.

#kubernetes #aws

If you want to learn SQL, or you know somebody who wants (or should, lol), or you want to refresh your SQL skills, you can use interactive lessons on SQL Bolt.

They're simple, but good enough to get up to speed with the basics.

#databases

​​For today’s Donations Monday I suggest supporting Pavlo and Naya, who are raising funds different equipment for the AFU.

This week their goal is to get 4 drones, 2 EcoFlows, and a thermal vision unit.

- Pavlo’s Requisites
- Naya’s Requisites

#donations #Ukraine

An article that could be a tweet (xeet?) but with more context.

tl;dr: avoid Helm hooks when possible.

I totally agree with the statement, yet an example in this article is rather weak. Anyways, if you need to have some imperative actions for your app, it’s always better to use higher level abstractions like ordering on the CD tool level or even an operator.

Having an init container that has access to the API is rather a security concern than a workaround.

#kubernetes

Here's a neat article with some good practices regarding security when configuraing an EKS cluster.

If you work with AWS and Kubernetes a lot, it won't give you any dramatic insights, but you could still use it as a checklist / cheat sheet when configuring a cluster, since it's easy to forget something when there are many moving parts.

#aws #kubernetes

This article with a clickbait noscript got my attention recently. It was even translated in Ukrainian by one of the largest Ukrainian developers-oriented media.

The most interesting part of this article, in my opinion, isn’t its premise and even not the points that the author is making (some of those points are 5 years late, TBH). The thing that caught my attention was what the author chooses to compare Kubernetes to. And those are managed platforms like Heroku, etc.

This is interesting for a couple of reasons: first of all it seems like other orchestration solutions are out of the table already. Second, it reaffirms the statement of Viktor Farcic (you can find those in the Den Vasyliev’s blog). Basically, the idea is that in the future Kubernetes will “disappear”. Not in the sense that it will fade away, but in the same way hypervisors have “disappeared”. The majority of us use them today, but we rarely think about what virtualization powers our cloud instances, etc. In the same way at some point there will an extendable API that allows one to run workloads and whatever cluster technology is underneath would be a concern of a cloud provider.

#kubernetes

A train edition of the CatOps Digest is here!

A couple of highlights from that digest related to CatOps itself:

- We are going to have a voice chat on Thursday at 20:00 Kyiv (19:00 Berlin) time.
- You can now follow CatOps on WhatsApp! I haven’t figured out yet if it’s possible to use markdown or any other formatting there but still.

#digest #newsletter

​​It's getting colder, so I would like to remind you to support the Air Defence Forces!

You can do it by donating to the joint fundraiser by Nova Posta and Come Back Alive - Protect the Sky.

The goal is to raise 330M UAH ($8.9M) for Ukrainian Air Defence.

#donations #Ukraine

​​Terraform variable validation, when 2+ vars depend on each other

Basically, where is the answer in SO how to do it in 0.13+ via locals, but it does not include some important details:

This check works only for known during terraform plan values of variables.
If value of any of variables in the check is not known during terraform plan, the check will be skipped and error message will pop up only after terraform apply in the next terraform plan.

The pic below is an example of how that check works.


Note, that there is a feature request to make able to refer to other variables in the variable condition check, but that's needs architecture redesign, so there no ETA when we can drop that hack.

P.S. You can achieve something similar by using lifecycle precondition and postcondition in case if you support only TF 1.2+


#terraform

Starting from February 1, 2024 AWS will charge their customers $0.005 per IP per hour

This number doesn't look huge without a perspective, however this might add some significant networking costs to some topologies. Thus, the best time to move your things into private subnets was a couple of years ago, the second best time is now.

#aws

Чисто нагадати, що сьогодні ми будемо робити Говорилку CatOps про менторство, а точніше: як стати хорошим ментором.

Стартуєм о 20:00 по Києву (19:00 по Берліну) в чаті.

Посилання на Говорилку

#voicechat