Chaos Engineering

23 Aug 2018 · Three minute read · on Gianluca's blog

At the Jazoon conference in Switzerland, I had the chance to speak at the Chaos Engineering panel with Russ Miles from ChaosIQ and Aaron P Blohowiak from Netflix.

The organizers put me in the panel probably because “chaos” was part of the title for the talk I just gave in the morning. I was too curious to mention that I never did it before, at least on purpose!

So I was really out of my comfort zone dealing with these two folks that know their shit so well!

I am sure that as Engineers we are part of the Chaos, we create entropy inside the system during every deploy and even if we have all the tests in the world the first time it is tough to make it work. But I indeed never associated the word engineering to chaos. And that’s the real challenge.

So, let’s define Chaos and Engineering altogether.

Let’s start with Chaos because it is the easy one, as I said we as developers create chaos, distribution creates chaos, and customers create chaos. If somebody tells you that his production environment is excellent, you should not listen to him, Production is a nightmare, complicated and painful place. At least if somebody uses it.

And if it is just a bit more complicated than a static site it never works 100%, the chaos governs it, and that’s where the sentence Engineering becomes essential.

Engineering at least for what I can understand means to be driven by data and not feeling. So associating these two concepts together you have a powerful way to measure the chaos.

I think you can’t avoid chaos, so the best way to handle it is to learn from what it generates in your system to anticipate unpredictable situations.

As developers, ops or devops we are pessimistic about our system, and we know that it will fail: servers crashes, CoreOS auto updates itself, third party services stop to work. Usual the answer is to wait for it to happen usually Friday night.

Chaos Engineering is an exercise, a practice to leverage “unusual but possible” situations as teaching vector to our system.

It is another tool to achieve resiliency and to test scalability.

Chaos Engineering doesn’t bring down all your production system in an unrecoverable way. It designs exercises that you and your team will use to increase your operational experience and confidence.

Observability is a sort of requirement to understand how a chaotic event changes the “normal” state of your system. But from another point of view a chaotic even shed some light for a particular part of your system showing up lack of monitoring and instrumentation.

There open source framework like Chaos-tookit or famous tools like chaos-money.

I will try to start with some very simple example without writing too much code. I will get out from my system these metrics:

  1. Number of requests (probably from ingress/nginx)
  2. The number of requests with status code > 499
  3. Http request latency

After that, I will try to simulate an outage removing or scaling down particular pods (the one that gets all the traffic) and I will look at how the metrics will change and how long it takes to recover.

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