Page 4 - Jacob Emcken

S3 presigned URL generation with Babashka

A while back, I needed to generate presigned URLs for S3 objects in Amazon Web Services. I wanted to use Babashka (Clojure scripting), to avoid my painful friend from the past - Bash.

I looked all the usual places for a Clojure-friendly approach, but even Cognitect’s AWS API did not have any means to presign URLs. Everybody seemed to reluctantly tolerate having to use AWS Java SDK directly for presigning URLs.

— Java interop, oh joy 😣😅

Being forced to use AWS Java SDK would mean a no-go for Babashka. Also, based on how often similar questions pop up, I felt it deserved a better solution.

Upload files to SharePoint using Babashka

My team and I were publishing a specific set of files several times weekly and we were obligated to put them on Microsoft SharePoint for non-technical people to be able to find them. After all, it is fair to not assume everyone knows their way around GitHub or how to run small pieces of code.

The tedious file upload to SharePoint was done manually until recently when Babashka came to the rescue and helped leverage our CI/CD pipeline.

How to compare JSON files offline

At work, I needed to compare some huge (almost identical) JSON data structures.

Since the data was potentially sensitive, I wanted to do it offline. Sending data over the wire to one of the myriad of online services was a no-go.

There are probably built-in tools for IDE’s like VS Code, Emacs and the like, but I wanted something I could use on the Linux CLI

Who am I

I am many things.

Upon reflecting the following words come to mind: husband, father, son, colleague, friend, philosophical, idealist, perfectionist, patient, empathetic, respectful, forgiving, fair, fearful, stubborn

Social media etiquette with the help of AI

There are many both really awesome and really horrible stories about how the internet is shaping our lives in the 21st century.

Social media despite its cool aspects also provide us with at least two problems:

• The harsh tone often found in debates.
• The amount of (useless) content.

Both problems have made me more or less quit social media, but I am hopeful that AI will be able to counter the harsh tone.

A very small PDF for testing

For testing, I often find myself prioritizing having small data sets because they are easier to comprehend. Also, the small size helps emphasize what is being tested when irrelevant data is absent.

Today, I needed a PDF for testing. Following the same principles, I sought out “the smallest (valid) PDF” and ended up on StackOverflow.

Constructing dummy JSON Web Token (JWT) using ClojureScript

JWT seems broadly used around the internet for all kinds of services and I wanted to use it for a service of my own.

To increase testing speed while interacting with the backend, I wanted to be able to rapidly create new JWTs to see the effect of different payload structures.

Writing an app for Google Cloud Run using ClojureScript

As part of a project I needed to handle webhooks from Hubspot (a CRM), and since the implementation turned out nicely, I thought it would be worth blogging about.

The reason why the app ended up in Cloud Run and written ClojureScript was to avoid the hard coupling to the main application.

All the code is available on GitHub.

A recurring core.async pattern

I’ve found myself using Clojure core.async in a very specific way on several occasions, and I thought it might be worth sharing.

MongoDB profiling

When running MongoDB in Docker, diagnostics logs are sent to STDOUT by default. Since MongoDB version 4.4 these logs have been in a structured JSON format, which makes it a little cumbersome to use the profiling tool in mtools.