DevOps is an approach to IT that radically alters the traditional relationship between development, maintenance and operation of software. The traditional separation between Dev and Opsbrings with it a substantial amount of waste in terms of elapsed time and budget. This waste is caused by differences in way of working, attitude and hand-over inefficiencies. The waste is exacerbated by accountability mechanisms that incentivize Dev and Ops departments to erect barriers, to protect themselves in case the other side fails to fulfill its responsibilities (“cover your behind”).
In DevOps, this waste is largely eliminated by making one team responsible for both DEVelopment and OPerationS of applications. Supported by extensive automation (mostly by open source tooling) of testing and deployment, DevOps allows organizations like Facebook, Netflix and Google to deploy new releases into the Cloud on a daily basis. This is quite an improvement over the usual “once or twice a year” releases seen in traditional software products, and it gives organizations tremendous agility in reacting to market developments.
DevOps appears to be most successful in end-user facing (front-end) applications that run in public or private clouds and have a web-based user interface. The tooling supporting the approach is fascinating, especially in the way it ensures quality control: see Netflix’s Dianne Marsh take on this tooling at this year’s Saturn conference. But how does DevOps impact the architecture of the software that is developed with it? So far, I have found three ways in which DevOps influences architecture:
- Architecting for deployability. Of all the quality attributes that a system may have, the one that is most directly related to DevOps is the ability to quickly deploy new releases into operation, with as much automation as possible. As I already mentioned in a previous blog, Stephany Bellomo and Rick Kazman of the SEI have made a study of this, and so has Len Bass of NICTA. An important consequence for architects appears to be the necessity to simplify and streamline the design. This includes standardization of infrastructure components, but also removing architectural elements which were originally intended to ensure other quality attributes, now overruled by the higher priority of deployability. One remarkable example of streamlining the SEI researchers found was the removal of an Enterprise Service Bus in one organization: originally implemented to enhance connectivity and modifiability, the ESB was found to be an obstacle to the speed of (automated) deployment and removed in the transition to DevOps (just an example – not a tip, ESBs generally have no quarrel with DevOps).
- Architecting for systemic resilience. As the speed and scale of deployment increases, chances are that from time to time stuff (services, app, APIs) that your software depends on may not be available for a few minutes or hours. Your software needs to be able to cope with this: the system as a whole needs to still be as available as possible. Your particular piece of the solution needs to stay alive, even if the whole world turns against it. Organizations like Netflix harden their system (and I guess their developers!) by actually making things worse: their simian army of chaos monkeys, latency monkeys and so on wreak havoc in test and production(!) environments. As Netflix says, “the best defense against major unexpected failures is to fail often”.
- Consolidated development architecture. In software development the target architecture for a solution has always put constraints on the set-up of the development environment, but with DevOps, it becomes almost impossible to see the development and operational environment as separate entities. From an architectural point of view, the development and target environments form one system with three main categories of users: developers, operators and end-users. One could even argue that that first two of those categories are the same in the DevOps philosophy. Many quality attributes affect all these user categories, and many architectural decisions have impact across the board as well. In DevOps, an architect (or “master builder”) does not design a target architecture after which an appropriate development toolset is selected: the whole ensemble forms one consolidated solution, with one solution architecture that addresses the combined architectural concerns for development and operation.
So as an architect, you may need to learn three new things: 1) to remove stuff rather than add stuff, 2) to design failure into your solution and 3) to design a consolidated development environment into your architecture. And you had better learn fast: Gartner calls this architectural approach “Web-scale IT”, and predicts that by 2017 50% of global enterprises will be using it.
What other aspects of architecture do you think is impacted by DevOps and Web-scale IT? Please leave your comments and let me know what I missed.