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As I’m writing this, we’re in the middle of our yearly load testing process.
Since a couple of years now, trivago conducts regular production load tests. We do this to test if all our services sustain the increased load we experience during the summer and winter months.
This year is now the 2nd time, where we also do another test: A "regional failover" test.

With the rewrite of our core product web application, we moved from a PHP/JavaScript tech stack to a Next.js stack. One of the most significant changes for developers was the switch to TypeScript, which most of us had not had a lot of experience with, previously.

One of the many responsibilities of a Site Reliability Engineer (SRE), is to ensure uptime, availability and in some cases, consistency of the product. In this context, the product refers to the website, APIs, microservices, and servers. This responsibility of keeping the product up and running becomes particularly interesting if the product is used around the world 24 hours every day like trivago. And just like in the medical profession, someone has to be on call to react on failures and outages outside of the office hours.

From April 2020 until the end of 2021, we have put trivago’s web frontend on a new tech stack. Having moved away from a quite large PHP codebase and our home-grown JavaScript framework Melody, trivago now runs on a Next.js application, written in TypeScript.

Scalability and availability are key aspects of cloud native computing. If your microservice takes five minutes to start up, it becomes very difficult to meet the expectations because adjustments to traffic changes, regional failovers, hot-fixes and rollbacks are simply too slow. In this article, we show how we solved this and a few other problems by taking control of the process of updating our data and storing it in a highly available Redis setup.

Throughout last year I had the opportunity to participate and collaborate on multiple research initiatives in the field of Natural Language Generation (NLG) in addition to my responsibilities as a Data Scientist at trivago. NLG is the process of automatically generating text from either text and/or non-linguistic data inputs. Some NLG applications include chatbots, image captioning, and report generation. These are application areas of high interest internally within trivago as we seek to leverage our rich data environment to enrich the user experience with potential NLG applications.

At trivago we operate on petabytes of data. In live-traffic applications that are related to the bidding business cases we use our in-house in-memory key-value storage-service written in Java to keep data as close to calculation logic as possible.

Have you ever wondered about how to create components that not only change their appearance according to the viewport’s width but instead also transform according to their parent element’s sizing? This might be the case when you have a card component that has the classical vertical layout on mobile:

At trivago, we run webservices with complex backends in different regions around the globe 24/7. Our system is being iterated and developed on a daily basis. Naturally, mistakes will be made and something will break eventually. Engineers being on-call are the first responders to issues with negative impact on our users and the business.

I’m happy to share that trivago has released a Prettier plugin which sorts import declarations in TypeSCript and JavaScript modules for a given configured order. Throughout this article, I’ll explain to you the motivation behind this Prettier plugin and how it works in detail.

trivago is the home to 500+ tech specialists from all corners of the globe – each with their own unique background and story of how they ended up here. Our trivago Tech Check-in series focuses on individual engineers' experience during their time at trivago. In this edition, you'll meet Mohammad Abed – a frontend software engineer who has been with trivago for 11 months now and is working on our Express Booking product.

In the middle of summer 2021, we hosted one of our favourite annual events of the year - trivago Tech Week! This year’s tech week had a new, hybrid format, featuring a wide variety of talks and exchange forums, hosted both by internal talents and external speakers. To make things even more engaging, the week included virtual opportunities for talents to gather and converse across departments, a gaming tournament and a highly anticipated live-music concert to tie everything together!

While engineering, we fix bugs, create new systems, build workflows and establish processes. Our job is to change things. Changing things can involve mistakes that ultimately lead to the failure of a particular system. To learn from these failures, a retrospective is helpful to get to the root of this problem. In the tech industry, a Blameless PostMortem is the right tool for this job.

When was the last time you booked accommodation without checking its photos? Most probably never! Because having imagery information makes our decision-making process much easier and faster. However, picking up the best possible images of a hotel to show to the user is an interesting problem to solve, because it can be a naive random selection or a sophisticated machine learning model to know what the user truly wants at that moment.

When operating applications in Kubernetes, proper lifecycle management is crucial to enable Kubernetes to manage applications correctly throughout their different phases: startup, runtime and shutdown. Improper or incomplete lifecycle management can lead to incidents with unforeseen and difficult to debug application behavior, such as random CrashLoopBackOffs, broken/zombie services not being restarted or even entire services not becoming healthy after a scheduled restart.