Sustainable Software Development

White Apple Magic Mouse Beside Green Leaves

When you’re in the zone it can be hard to think about the future of the code you’re writing, but the time you’re spending writing it is just a fraction of its lifespan. Code may be written once, but it will be edited a few times, perhaps copied once or twice, and likely executed many hundred, if not thousands or millions of times. You as a software developer will (hopefully) have a long and productive career in software development, as will the team you work with. And finally, you also do your work on planet Earth (hi to any readers on the ISS), and without it you’d really struggle.

When creating or modifying an object or system that we intend to last for a long time, it is crucial to consider sustainability. This includes factors such as the sustainability of the source code, your or your team’s ability to work on it for an extended period, and the software’s impact on the environment. All of these aspects are significant and should be carefully considered.

If you’re working in a scrappy start-up, fighting for survival, then the long-term maintainability of your code will not be important to you. In most cases though, code can be expected to last for a significant time, and the cost of maintaining it will significantly outweigh the initial cost of writing it.

Code that is not maintained will accumulate problems. Libraries it relies on will have new releases, as will the operating system it runs on. These will provide new features, fix bugs and solve security vulnerabilities. Software that has not been touched for a while requires significantly more time to make simple changes, compared to software which is regularly altered.

The DevOps movement helps significantly with maintainability, as any manual process ages very quickly. Even with excellent documentation, it isn’t easy to reliably follow a process you’re not familiar with. Automation, particularly the build, test and deployment steps, are well worth the time spent on building them. If you can combine a tool like Renovate with a high-quality test suite, and a continuous deployment pipeline, you can focus on other things, safe in the knowledge that your application is being kept up to date with the latest security fixes.

Beyond automation, how you write code will affect how sustainable and easy to maintain your code base is. This doesn’t mean you should add comments everywhere, indeed if you need comments then your code could probably be clearer. Not that there aren’t times when comments to explain why a section of code is written as it is are needed, but they should be rare.

When writing your code, think about how it will be read, and how it will be maintained. This starts with the language you use, as well as the libraries, frameworks and design patterns you choose. No language, library or framework is perfect for all situations, but there are bad choices. The two things to consider when making a choice are how much knowledge of the technology there is in your company (or how much time you are willing to invest in training), and what the community of the project is like.

While you might think Kotlin (to pick a random example) is the perfect choice for your new application, if no other apps in your company use Kotlin, and knowledge amongst your colleagues is low then it will be hard to maintain in the future. Similarly, with frameworks and libraries, the ability for other developers to jump between applications and focus on the logic and not the surrounding implementing details can hardly be overestimated. Languages and libraries don’t by themselves deliver value. They might enable you to deliver value quicker compared to other choices, but only if you can unlock that advantage, and maintain it long-term.

The other aspect is the community around the technology, and where you are comfortable sitting on the technology adoption lifecycle. It’s certainly a good idea to keep abreast of new developments and experiment with them by building things you’re happy to throw away once you’ve learned about them. But betting your company on a brand new library, that’s only existed for a month and has one contributor, has a high risk of you depending on code that’s been abandoned and either needing to migrate away from it, or commit to supporting it yourself. At the other end of the lifecycle, if you wait too long to adopt, or stay with a dependency for too long, then it may move out of support and be abandoned too - exposing you to unpatched security vulnerabilities, and conflicts when other dependencies drop support for something you are using.

Most software development projects last many months or years. For people working in an Agile fashion, there might not even be a specific end goal, just an endlessly evolving set of requirements and software that is growing to meet them. Burnout is a significant issue in software development and as a leader, it is your job to recognise the signs and work to prevent it. If your team burns out, productivity and quality will collapse, and the costs will be much greater than if you had worked more sustainably.

Common reasons for burnout are poor working conditions, pressure and unrealistic deadlines, and a culture that doesn’t prioritise learning, improvement or balance in the demands on team members. This is a huge topic, far too big for one blog post, but sacrificing a bit of speed now will result in happier developers and a much more sustainable development process.

One of the most demoralising things about being a developer is working on software that is hard to change, but you don’t have the permission, or time, to make the needed improvements. By dedicating an appropriate amount of time to tech debt reduction you not only end up with more sustainable software but a more sustainable culture of development too. As a leader, you might need to defend this time, but by looking at security vulnerabilities in dependencies, or the risk that you will no longer be able to get support should you need it, it is possible to build a strong business case for this work.

The most common thing your code will do is run. Whether it’s executing a thousand times a second, or once a week when someone runs a report, it’ll spend more time running than you spent writing it. Computers use energy, need materials to build, and cost your company money to run. If you can halve the time it takes a process to run you’ll give your customers a better experience, save your company money, and reduce the impact your code has on the planet.

A centralised database clearly has a significantly smaller environmental impact than a blockchain-based ledger - even if you take into account techniques like Ethereum’s Proof of Stake. Which one is better depends on what your priorities are, and what tradeoffs you are willing to make. They are tradeoffs though, and they demand consideration during your design process.

Not all tradeoffs are quite as extreme as the database vs blockchain example. You might be working on a report which does some algorithmic processing of data. If you’re writing in Python it’ll likely take longer to run than if you replace that section with highly optimised C code. Again, there are no right answers, but the Python code will likely be significantly easier for your team to maintain in the future, so perhaps that is worth the extra costs incurred by the longer run time.

It’s easy to focus on the joy of building a complex system, one that will be useful to your customers and make money for your company. But an often overlooked customer is you in the future, or those who come after you and have to look after the system you are now building. When you are choosing the technology you will use and the systems architecture you’ll implement, make sure you consider how easy it will be to maintain, how your team will work without the risk of burnout, and the impact your design choices will have on the planet.

Have you chosen one technology over another because of the ease of maintainability? Have you changed architecture because of environmental concerns? Let me know in the comments below.

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