Testing a change properly before it’s merged is one of the trickier parts of software development. Preview Environments is a tool that started life as a university dissertation and is now part of how our team works every day.

How it works

1. Automated builds: when a developer opens a pull request, the code is built into a Docker image automatically.

2. Live, isolated environments: the image runs in its own environment, so developers and testers can try the change straight away.

3. Close to production: each environment mirrors production, which reduces the risk when it’s time to deploy.

What’s changed for our team

Feedback loops are faster, collaboration is easier and issues are caught earlier, before they reach the main codebase. Because it plugs into our CI/CD pipelines, it improves code quality without adding extra steps.

Challenges along the way

• Optimising Docker builds to keep images small and fast

• Managing short-lived environments so they don’t waste resources

• Making sure it scales for larger teams and more complex projects

From dissertation to daily tool

Turning an academic project into a production tool meant refactoring the code for robustness, gathering feedback from the team and fitting it into the workflows we already had.

What’s next

• Running automated tests inside each environment

• Monitoring resource use to improve efficiency

• Expanding into the cloud for greater scale

Want to speed up how your team tests and ships changes? Get in touch to see how Preview Environments could work for you.