Caching resized images on S3 with Databricks

When you are training a machine learning image classification model, you often need to resize the images your dataset into smaller ones. When you retrain your model on new data, you resize the images once more. In this blog I’ll share how S3 can be used to cache the resized images.

Sorting an array of a complex data type in Spark

Today we’ll be looking at sorting and reducing an array of a complex data type. I’m using Databricks to do Spark, but I’m sure the code is compatible. I’ll be using Spark SQL to show the steps. I’ve tried to keep the data as simple as possible. The example should apply to scenarios that are more complex.

Adding True/False and list value widgets to your Databricks notebook

As an engineer, I love to parametrise my applications. That’s why I love the widget-feature of Databricks notebooks, which allows me to do this with a nice UI. In this blog I’ll explore how to build a True/False widget and a list widget. I also show how to validate the values of required fields.

Investigate problems due to User-Agent using Bash

Last week we had some problems with the Google Ads bot. It was not able to crawl a bunch of URLs while the browser had no problem getting through. The only difference was the User-Agent. This send us on a debugging journey through Cloudflare, gateways and micro-sites. To assist us, we’ve created a small bash script to visit an URL and show some debug info.

Trigger Lambda for large S3 Bucket with SQS

At Wehkamp we use AWS Lambda to classify images on S3. The Lambda is triggered when a new image is uploaded to the S3 bucket. Currently we have over 6.400.000 images in the bucket. Now we would like to run the Lambda for all images of the bucket. In this blog I’ll show how we did this with a Python 3.6 script.

My Little List of Tools for Prototyping

As a developer I love to prototype to see if an idea works. Thinking big and starting small is actually one of Wehkamp’s principles. And, let’s face it, that’s not easy!

Usually it starts by getting an idea of the core concept that should be validated. Especially when working with teams, communication is key. This list of tools helped me over the years to draw or code out some of these concepts and get a discussion started.

Every tool on this list is free and online.

Convert JsFiddle to SVG using Node.js

I love SVG, but sometimes they are hard to create, especially when you need to visualize diagrams. HTML is way easier to program. So why not combine them? Can we use HTML to generate an SVG? And can we use JsFiddle to generate that HTML?

AWS Lambda Size: PIL+TF+Keras+Numpy?

At Wehkamp we’ve been using machine learning for a while now. We’re training models in Databricks (Spark) and Keras. This produces a Keras file that we use to make the actual predictions. Training is one thing, but getting them to production is quite another!

The main problem we’ve faced was that it was too big to actually fit into a lambda. This blogs shows how we’ve dealt with that problem.

Installing Ubuntu to Windows Server 2019 (WSL)

These scripts will help to install Ubuntu to a Windows Server 2019 installation. It will download Ubuntu and activate the Linux Subsystem on Windows (WSL).

Building a high performing last viewed list using Redis

We live in a day and age in which we can choose a data-store that matches the characteristics of our apps and (micro) services. Lately we’ve been looking into Redis as a high performing store for last viewed items. In this blog I’ll look show how to create a POC with the redis-cli and then implement it using .NET Core. We’ll be using the sorted set structure.