I wanted to do some REST client stuff in PHP with cURL today. It has the neat CURLOPT_PINNEDPUBLICKEY option that one can use to set the certificate fingerprint. Unfortunately its a bit cumbersome, as one needs to enter the fingerprint in base64, instead of just the format the browser displays if you look at the cert directly (e.g.: 529728d7c43746c0bb02ac4a4c3bffb7028ac1591ecb08b6a0721a660aa1d3ce). Luckily we can just get the correct fingerprint format using this one command: openssl x509 -pubkey < cert.crt | openssl pkey -pubin -outform der | openssl dgst -sha256 -binary | base64 You can download the cert using Chrome or Firefox and then use the openssl command above to get the correct base64 formatted string (e.g.: WcHR5sNo7T3ZDL6b/dLgFFETh4tdkm8SAHXfqKLo9wo=). The same works for the Symfony HTTP Client library that also expects the same format (that is further passed on to cURL) for the peer_fingerprint options entry. The official docs unfortunately do not mention this at all and just replace the formatted value by ‘…’. Oh well.

Years ago I worked at a consulting company writing software for a German car manufacturer. This project was a multi-year endeavor and had all the bits and pieces in place to become the next generation legacy software that nobody wants to touch. We are talking about a multi-million investment and a 50 person team of engineers, business analysts, architects and managers. We were essentially building a Java EE monolith with a Javascript-backed frontend. Back then, in 2017, Kubernetes was starting to emerge as an interesting option and we experimented around with deployments, but it didn’t affect the architecture decisions too much. We continued to build a humongous monolith and the project was only set to go live after the core functionality had been built. About four years in, the team was finally ready to launch the first alpha to select customers. Yes, you read this right: we proceeded with development for a long period of time without ever testing that the architecture and resulting system could sustain the load. Internally we were doing Scrum, but only occasionally we did a hand over to fit the car manufacturer’s waterfall project planning. I left the consulting company before the system went live. […]

Sometimes you need to provide a legacy access to various downloads or proxy some requests to a different endpoint, that might not be running in your cluster. One can natively redirect such requests with having to add additional deployments / containers to your Kubernetes cluster. There is a special type of Kubernete’s service object that simply points any traffic to that external DNS name. This isn’t really document all too well but eventually you will find enough issues and pointers to frankenstein a solution together. For anybody else looking on how to do this correctly, here is run down with nginx-ingress-controller:0.19.0 that worked for me. First we create a normal ingress object, that allows us to terminate the SSL and look into the path of the HTTP request and decide if this is a request that is relevant to be proxied.  Lets quickly take a look at what is going on here. We first configure our Ingress Controller to use nginx and enable automatic provisioning via our cluster ACME/cert-manager. Then we instruct nginx to rewrite the target URL to add the bucket. This way, we can swap buckets without the user facing URL having to change. (Notice to not include […]

So in the last four months (October 2015 to January 2016) I had the pleasure to work with the team of students at Texas A&M university. I got to experience a whole different culture of studying and learning – a different approach to tackle the issues of the future.

Compared to German universities, Americans have adopted a class like education even in higher education. While we at the TUM have to aggregate and learn most of the material ourselves, students at A&M tend to get the content and materials prepared in form of text books.

My main goal was to work on my bachelor thesis though, where I looked at a new way to develop web applications using Meteor and Angular to integrate wearables into the web-experience.

You can download the thesis here. It’s also on the website of the “Lehrstuhl für Betriebssysteme”.

I’m glad to be part of the amazing community at codementor.io. In the past years I’ve been able to talk and help many different people with a range of problems. Often some hints and good advice was enough to point them in the right direction and I really enjoy teaching other people. Codementor recently approached me and asked me if I could contribute some questions from my experience in the last years to their blog post “25 PHP Interview Questions”. I’m happy they found my suggestions useful and featured me in that article! Hope it helps some developers that are just getting to know the world of PHP and all its hiccups. Don’t forget to check out my profile on codementor!