Emarsys Craftlab Articles

Between 2018 and 2022 I wrote a handful of articles for the Emarsys Craftlab blog, the engineering blog of Emarsys, where I worked as a software engineer. They cover whatever I was busy with at the time: hands-on security training, organising an overgrown photo library, and lessons from working on large production systems.

Offensive Security Workshop: Why and How? Part 1. and Part 2., published in June and July 2018, describe how we replaced the usual slide-based security awareness training with a workshop where developers attack a prepared environment themselves. The first part covers the why and the planning: small mixed groups, challenges picked along the OWASP Top 10 and thorough preparation. The second part covers the execution, from the warm-up on HTTP and browser DevTools through the hint system for stuck participants to closing with real-world case studies, and the feedback that convinced us to keep running it.

4 tips to organise your photo collection better, published in January 2019, is a more personal one: four command-line techniques for cleaning up a photo library with exiftool and plain Unix tools, from sorting by extension and deduplicating with hashes to organising photos by their EXIF creation date and camera model.

Lessons I learned from working on a high-load legacy application, published in April 2020, sums up what half a year on a high-load legacy system taught me: roll out changes carefully behind feature flags, write clean code and logs that are actually useful at scale, and pair program so knowledge does not pile up in a single head.

What we learned from porting our web service to a new tech stack, published in January 2022, collects the lessons of migrating a live production service to a new stack without downtime: start with the core business logic, invest in testing and monitoring, communicate with the affected teams, and plan the decommissioning of the old system before you begin.