https://f0o.dev/ Recent content in Ohai on Daniel 'f0o' Preussker Hugo -- gohugo.io en-us Mon, 01 Jul 2024 00:00:00 +0000 https://f0o.dev/posts/2024/07/ovn-oddities-possible-route-leaks/ Mon, 01 Jul 2024 00:00:00 +0000 https://f0o.dev/posts/2024/07/ovn-oddities-possible-route-leaks/ It seems that the new OpenVirtualNetwork setup in OpenStack can cause some big route leaks. The reason for that is relatively simple, OVN relies on OVS as dataplane and OVS uses it’s own kernel driver to simply “inject” the packets into the network interfaces that has been selected based on kernel routes. OVS has no notion of VRFs and by default will scrape all routing tables (Version 2.17 limits this to the default table only! https://f0o.dev/posts/2024/05/openstack--ovn--full-bgp-tables-heaven/ Fri, 17 May 2024 00:00:00 +0000 https://f0o.dev/posts/2024/05/openstack--ovn--full-bgp-tables-heaven/ It’s been some time since I wrote something. Not because I got lazy but because I’ve been cooking something. We all know and love OpenStack and recently they decided to deprecate the Linux-Bridge Neutron ML2 Driver and replacing it with OVN to provide a more future proof way of providing overlay networking and dynamic networking. OVN, or Open Virtual Network, is practically just OpenVSwitch with some management and clustering tooling. https://f0o.dev/posts/2023/06/leveraging-portage-for-os-dev-part-1/ Wed, 14 Jun 2023 00:00:00 +0000 https://f0o.dev/posts/2023/06/leveraging-portage-for-os-dev-part-1/ I believe it’s everyone’s fascination to create their very own Operating System and it’s been exactly that fascination paired with a “healthy” dose of “How hard can it be?” that got me into it. There are a handful of very good resources out there already. I wont repeat what Linux From Scratch or OS Dev Wiki do but rather go a different approach. This approach is by no means unique and is actually being used by Flatcar Linux , ChromeOS and many more. https://f0o.dev/posts/2021/12/logging-insanity/ Fri, 03 Dec 2021 00:00:00 +0000 https://f0o.dev/posts/2021/12/logging-insanity/ How complex can you make log forwarding? You’d imagine not very much, after all - what’s there to complicate? You get the logs, move them to a processor and then just write them into the persistence - right? You’d be surprised how complex you can make that… This is a simplified view of what I discovered in the wild. +---------------+ +-----------------+ | Application | ---- Stdout ----> | Docker Engine | +---------------+ +-----------------+ | \. https://f0o.dev/posts/2021/11/iwlwifi-madness-aka-dont-buy-intel-11n-cards/ Tue, 30 Nov 2021 00:00:00 +0000 https://f0o.dev/posts/2021/11/iwlwifi-madness-aka-dont-buy-intel-11n-cards/ I got a new little workhorse from work with an Intel Corporation Wireless-AC 9260 (rev 29) using upstream iwlwifi. This is not about how the Linux Kernel v5,5 Nuked WiFi on iwlwifi but more about the extreme annoyance that recent 802.11n capable Intel Wifi cards experience when connected to 5Ghz networks. The experienced issue is a sudden stall of network connectivity while the card still claims to be connected to the AP but upon inspection of the kernel logs shows a nice trace (at the bottom of the post) indicating that there is a firmware issue and the physical device (phy0 in this case) needs a reset. https://f0o.dev/cv/2021/09/founder/chief-technology-officer/ Wed, 01 Sep 2021 00:00:00 +0000 https://f0o.dev/cv/2021/09/founder/chief-technology-officer/ Work description: Pioneering hyperscale FaaS architecture Create and maintain a distributed, highly available, and scalable microservices architecture Key Achievements: Implemented a hyperscale global architecture for pennies a day as well as maintaining >100% SLA. NoOps Approach into hands-off operations, beyond DevOps. Technologies Used: aws, azure, gcp, nodejs, python, golang, mongodb, amqp https://f0o.dev/posts/2021/07/hiring-code-challenges/ Tue, 20 Jul 2021 00:00:00 +0000 https://f0o.dev/posts/2021/07/hiring-code-challenges/ Never meet your heroes. Funny expression, on the one hand it’s about not meeting them so you wont get disappointed by the fact that they’re just humans; On the other it also shows that there’s nothing special about them either, so you can become one too. For me this just happened after a recruiter asked me about a Senior Site Reliability Engineer position at a crypto exchange. I always spoke very highly of them, specially their Security and Engineering departments. https://f0o.dev/posts/2021/07/cloudflare-pages-or-free-ci/cd-runners/ Thu, 08 Jul 2021 00:00:00 +0000 https://f0o.dev/posts/2021/07/cloudflare-pages-or-free-ci/cd-runners/ So recently I moved my blog, this very page you’re reading right now, onto CloudFlare Pages. And I love it. Apart from the part where their hugo version is super old. But Hey! they let ME define an own command to run and look at that; I’m even allowed to download things! So this made me happy because now my blog can be served by CloudFlare’s edge network instead of my gentoo-raspberry-pi. https://f0o.dev/posts/2021/07/how-i-built-one-of-the-largest-multicoin-mining-pools-in-early-2010s/ Fri, 02 Jul 2021 00:00:00 +0000 https://f0o.dev/posts/2021/07/how-i-built-one-of-the-largest-multicoin-mining-pools-in-early-2010s/ Some of you might actually know this story - after all, I’m not very secretive about it. So this was around 2011-2012; The S-Crypt Boom hasn’t yet fully started and ASICs weren’t mainstream. My friend managed to be on the shortlist of some S-Crypt ASICs, the first of it’s kind actually, to be shipped to us in Europe directly from the factory. This was big news as the ASICs were far superior from any CPU/GPU mining back then, obviously. https://f0o.dev/posts/2021/06/hyperscale-dirt-cheap-serverless-setup/ Wed, 16 Jun 2021 00:00:00 +0000 https://f0o.dev/posts/2021/06/hyperscale-dirt-cheap-serverless-setup/ Hyper Hyper I’ve been asked by a friend to have a look at their hosting concept for this very simplistic, almost entirely Web-Based, Desktop & Mobile App Backend. Of course there was lots of talking from their IT staff about Dedicated Servers and such. No wonder the preliminary cost estimates were somewhere in the 1K USD MRC range… Without even having paying customers yet… So I looked at their tech-stack and to my surprise their stack is almost entirely based on JavaScript or TypeScript in one way or another.