Prezi Got Pwned: A Tale of Responsible Disclosure

The emails that arrive in a security engineer’s inbox can be put into three broad categories. 1) Readable Details of a new Budapest craft beer bar Links to articles about actual real-life hoverboards…

A Kubernetes crime story

The problem with having a great monitoring system is that you notice problems you couldn’t notice before. This is exactly what happened to us when we migrated our Nginx based reverse proxy to Kubernetes: we noticed that tail latency (p99) got somewhat higher for a few of our services. Increased p99 latencies start on 7/24 In…

Effortless mass change management with Hammurabi

If you have ever developed microservices, you already know some of the challenges around it. If it’s done right, development can speed up, the cognitive complexity of the services can be decreased, and there are many many more advantages over monoliths. On the other hand, you have to solve different…

Short-Lived Functional Teams Work — or — the QA SWAT Team

Functional teams have gotten a bad reputation in the startup community. There is no dearth of job listings for full stack engineers, or blog posts about the virtues of the DevOps movement. The consensus is that we shouldn’t partition expertise in a single team, and we shouldn’t restrict responsibility to…

Oh Android, we’re like so future.

Bond had been waiting for Prezi for Android for quite some time. Well, there are two answers. 1. The huge problem that’s always there:

In search of speed — debugging Elasticsearch performance

Background Here at Prezi, we use Elasticsearch to power the Explore pages for both Prezi Presentations and Prezi Videos. At the start of this year, we started running into performance issues with our cluster. Queries would take too long, some would timeout, resulting in 500 errors, high latency, degraded user experience…

My Three Days at Craft 2014

Changelog: A Tool Designed to Help You Recover Faster

Image via AndroidPolice When (not if) things break, it’s important to…

Outage of the Sentry

Yes. Prezi recently suffered two site outages that prevented people from accessing their prezis for a total of almost four hours. It caused a lot of people serious problems, embarrassment, and stress. We’re sorry, and we owe everyone not just an apology but also an explanation. However, the pun is appropriate…

Prezi — the Land of the Polyglots

“I speak Spanish to God, French to women, English to men, and Japanese to my horse.” —Buckaroo Banzai Ask any engineer “which programming language is the best?”, and you’ll get crushed by a deluge of answers ranging from stuff they started with in uni to something they…

Reactive Swift

UPDATE: ReactiveCocoa‘s new Swift API is out now. You can find my new post about how I upgraded this iOS app with the latest ReactiveCocoa on All The Flow blog. Reactive Swift: upgrading to ReactiveCocoa 3.0 If the title doesn't sound familiar to you, ReactiveCocoa is an FRP* inspired framework, counting remarkable usage in…blog.alltheflow.com Let’s go back in time to when Apple introduced Swift, the successor to good old Objective-C, it was a very…

Prometheus at Prezi: replacing 10 years of anti-patterns

What happens when you combine 10 years of architectural organic build-up and a lack of common best practices around monitoring? Bad on-call shifts, more outages, longer outages and a lack of technical flexibility. In our effort towards uniformity and reliability, we redesigned our entire monitoring stack and created a new…

Simpler Management of Modular App Development

This is…

How and why Prezi turned to JavaScript

Today we updated the Prezi player, which you can use to view and present your prezis. It is a huge change, completely moving the underlying technology from Flash to Javascript. Hopefully, nobody notices. It has been the biggest migration project of our working-lives, and has taken us almost four years…

prox part 4 — simplified redesign

Intro In Part 1 I described how the advanced type level programming techniques can be used to describe the execution of system processes. It was both a good playground to experiment with these and the result has been proven useful as we started to use it in more and more production…

prox part 2 — akka streams with cats effect

Intro In the previous post, we have seen how prox applies advanced type level programming techniques to express executing external system processes. The input and output of these processes can be connected to streams. The current version of prox uses the fs2 library to describe these streams, and cats-effect as an…

Performance Monitoring With Speedprobe

In the DevOps community, we all share common enemies: the insidious complexities of building and operating applications, the all-too reasonable, yet high expectation that users have for that application’s performance, and the scarcity of hours in the day. Time may be money, but it’s also our time, and the happiness…

Heartbleed Defeated

For those of…

Racing against race conditions

Some hours ago, we discovered a bug related to our Facebook/LinkedIn signup integration. It meant that in a very particular and unlikely set of circumstances, some people may have found themselves in someone else’s Prezi account. In the moments since discovering this problem we: mumbled expletives fixed the problem stayed…

How Prezi switched data centers on the fly

The pit crew can change the tires on a racecar in 12–14 seconds[1]. That’s insanely fast compared to the 29 minutes, bruised fingers, and oil stained pants that it took me to do the same thing with our family car, but the difference is quantitative, not qualitative. Every single tire…

prox part 3 — effect abstraction and ZIO

Intro The first post introduced the prox library and demonstrated the advanced type level programming techniques it uses. Then in the second part of this series, we experimented with replacing the streaming library from fs2 to Akka Streams. In both cases, the library used cats-effect for describing side effects. But it…

Technical Debt, a.k.a. “Not-quite-right-code” at Prezi

The…

Snakebasket — Recursively Install Python Dependencies

Plans Are Useless, Automation Is Essential

prox part 1 — type level programming in Scala

Intro I started writing prox at the end of 2017 for two reasons. First, I never liked any of the existing solutions for running external processes and capture their input/output streams. And I just returned from the scala.io conference full of inspiration; I wanted to try out some techniques and libraries…