I operate from the Netherlands and that makes my time zone Central European Summer Time (CEST). The data I handle is usually stored in UTC time. Whenever I need to crunch some data with Spark I struggle to do the right date conversion, especially around summer or winter time (do I need to add 1 or 2 hours?). In this blog, I’ll show how to handle these time zones properly in PySpark.

At Wehkamp, we use Google Analytics extensively to measure how many users are active. It is hard to correlate active users with your other statistics that “live” in Prometheus. In this blog I’ll show how you can use the Google Real Time API to produce statistics for active users, page views and screen views.

It is pretty easy to write your AWS ALB access logs to S3, but if you want to do something with them, you might want to add them to AWS Athena, so you could query them using plain old SQL. Let’s investigate how we can see which upstreams / targets are misbehaving.

Sometimes you just need to record the original message that was submitted to your API. My colleague Onno Pierik and I encountered such an event. We needed to record the original submitted SOAP message (body) and submit it (under certain conditions) to another service. To be honest: most of the scenarios I’ve seen so far end up with memory problems, so use with caution!

To make a setup more resilient we could allow for actions to be retried when they fail. We should not “hammer” our underlaying systems, so it is wise to wait a bit before retrying (exponential backoff). Let’s see how something like this could be done in Python. Note: this only works if actions are idempotent and you can afford to wait.

I’ve installed and configured AWS Vault in Windows. Now I need to execute some bash scripts which use account impersonation. I don’t want to setup AWS Vault again for Windows Subsystem for Linux (WSL), so let’s see how we can link AWS Vault using an alias.

There are a myriad of tutorials on Redis in almost every programming language. Many will cover how to make a to-do list, so why write another one? Well, I want to write a tutorial that is language agnostic and only uses Redis commands and Lua scripts (the build-in scripting language of Redis).

A Table of Contents helps users navigate (long) blog posts. I use them on both posts and post. The desktop version always shows the table on the right side in the sidebar (using a text-widget with a shortcode). On mobile, I’ll only show it on long articles, using a shortcode under the first paragraph.

In WordPress you have two main taxonomies: categories and tags. I use categories as a taxonomy tree. That is why I want to show the submenu on the category page. It does not come out of the box, so I created something that renders the submenu items for me.

Recently, I worked on my theme for KeesTalksTech. To gain performance, I need to rely less on plugins, that’s why I needed a simple way to show small lists of posts in my sidebar.

I’ve created 2 short codes: one that shows recent posts, used in the new section and one that shows specific posts, used in the highlights section.