Author Archives: erik

Migrating a mailserver to k8s

Posted on August 26, 2022 by erik

It has been a long time since I setup a mail server. It started with my first mailserver on linux somewhere in 2000 using sendmail and University of Washington IMAP. This setup was assuming mail delivery to local system users. … Continue reading →

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Moving an existing wordpress install to kubernetes

Posted on August 18, 2022 by erik

As part of moving everything that is running in VMs on my server to kubernetes, the old wordpress installation had to be migrated to kubernetes as well. The website was previously running in a linux container based on systemd-nspawn, using … Continue reading →

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Kubernetes Network Policy Tester

Posted on August 9, 2022 by erik

As mentioned in my previous post I would follow up with a tool for testing network policies. This tool is finally here and is available on github. It is written in python an available through install on PyPi.

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Securing network communication on kubernetes using network policies

Posted on July 23, 2022 by erik

An often overlooked topic in kubernetes is network security. This is probably caused by the fact that perople just assume it is secure by default because it is new, and because of the Service concept. The standard way to expose … Continue reading →

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Basic kubernetes infrastructure: RPM and container repo

Posted on July 4, 2022 by erik

As part of migrating all the stuff I have from virtual machines to a kubernetes infrastructure, some important pieces of infrastructure are needed. These are: RPM repository: I use custom RPM repositories for setting up virtual machines. These same RPMs … Continue reading →

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Automatic certificate renewal with Let’s Encrypt and DnsMadeEasy on Kubernetes

Posted on June 18, 2022 by erik

These days, it is ill-advised to run a website (such as this one), over HTTP, even if there is no security risk at all. When hosting your website on HTTP, users will see a warning triangle in the address bar … Continue reading →

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Hosting services on Google Kubernetes Engine

Posted on May 28, 2022 by erik

This post explains how to host services on Google Compute Engine, parts of this are applicable to regular (non-GKE) Kubernetes clusters as well. This post will cover: allowing multiple services to be deployed in different namespaces allowing multiple (sub)domains to … Continue reading →

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Optimal payment scheme for a Dutch Bank Savings Mortgage, using a Mixed Integer Linear Program

Posted on October 5, 2019 by erik

There is a special type of mortgage in the Netherlands (Bank Savings Mortgage or bankspaarhypotheek in Dutch), which I presume, does not exist anywhere else in the world. The construct is that you have a mortgage on your house for … Continue reading →

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Setting up up a deep learning box

Posted on April 30, 2018 by erik

After doing a number of courses on machine learning I now have some overview of what is available and how it all works. So now it is getting time to start doing some work from start to finish myself. To … Continue reading →

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Why finalizers are really bad

Posted on November 24, 2013 by erik

It is more or less common knowledge that using finalize functions in java is bad. For one, you are depending on garbage collection for cleanup and there is no guarantee when the finalizer will be called. Further there is also … Continue reading →

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