The Principle of Improvement
By: Adam Hawkins
Tags: DevOps, Software Development, Software Engineering, Sre

This episode completes our introduction to the three ways of DevOps. The previous two episodes introduced flow and feedback. Flow, the first way, establishes fast left to right flow from development to production. Feedback, the second way of DevOps, establishes right to left feedback from production to development, so using the state of production informs development decisions. The Third Way of DevOps, establishes a culture of experimentation and learning around improving flow and feedback.

Let’s frame this discussion using the four metrics from Accelerate: lead time, deployment frequency, MTTR, and change failure rate. Lead time and deployment frequency measure flow. MTTR measures feedback. Change failure rate measures experimentation and learning. Trends in these four metrics also reflect experimentation and learning.

Consider this scenario. There’s a severe 6 hour production outage. As a result the business has lost money and received angry emails from customers. This long outage window impacts the team’s MTTR. This bug — undetected by the deployment pipeline — caused an outage which increases the change failure rate. The team meets as soon as possible after restoring production operations. What do they do? If they apply the third way of DevOPs, then they would conduct a blameless post-mortem. The post-mortem would identify the root cause of how this bug entered production and what regressions tests to prevent it in the future. Hopefully they also discuss why it took six hours to restore operations and how they can be quicker next time around.

Here’s another scenario. A team ships new features on a regular basis but they don’t see the expected business results. They thought these features would deliver results but can’t figure out why they are not. What can be done? First, the team needs to step back and check their assumptions. Instead of going all in on big features, they can test their assumptions with tiny experiments released to a small segment of their users. If the results are positive, then the team should continue iterating. If not, then the team tries a new idea. Over time the team sees that they spend more time delivering on proven business ideas instead of ideas they assumed would just work. This approach is known as A/B testing or hypothesis-driven deployment from the lean IT school.

Both scenarios demonstrate a focus on improvement through experimentation and learning. However this only possible in a high trust culture. It’s not possible to conduct a blameless post mortem if people are afraid to say what they did to cause an outage. It’s not possible to conduct A/B tests if the organization does not see the value in validating business ideas through experiments. This is why leadership must promote these idea. I’m going to read one of my favorite passages from the DevOps Handbook. There are many wonderful passages in this book, but this is top tier without a doubt. The passage is great example of leadership’s role:

Internally, we described our goal as creating “buoys, not boundaries.” Instead of drawing hard boundaries that everyone has to stay within, we put buoys that indicate deep areas of the channel where you’re safe and supported. You can go past the buoys as long as you follow the organizational principles. After all, how are we ever going to see the next innovation that helps us win if we’re not exploring and testing at the edges?

I just love that quote — there’s just so much good stuff there. It describes a high trust culture guided by safety and aligned through principles. The four metrics (lead time, deployment frequency, MTTR, and change failure rate) are SLI’s. DevOps is a set principles that guide organizations to move those SLIs in the right direction, and when done right the results are outstanding. You just need to ask how can we improve? If you can stick to that then you’ll uncover that improvement of daily work is the daily work.

Alright, that’s it for principle of experimentation and learning. These three ideas will come back all the time on the podcast, but hey you always come back to these episodes if you need a refresh. Head over to the podcast website smallbatches.dev for links and free ebook on putting continuous improvement into practice.

Until the next one, good look out there and happy shipping!