MAAS (metal as a service), is a Canonical product which allows for very fast server provisioning and data centre management. Around 2014, work began to build a rich UI for MAAS, primarily using the AngularJS JavaScript framework from Google. AngularJS today is in long term support (LTS) and due to reach end-of-life in 2021. This year we began the work of transitioning away from AngularJS in anticipation of this impending EOL to more contemporary tooling.

Evaluating Angular vs React

Google’s recommended upgrade path for applications built in AngularJS is to transition to the Angular framework. Despite the similarity in naming, Angular is very different from AngularJS architecturally, and the migration process is non-trivial. While components (allowing for the now ubiquitous uni-directional data architectural pattern) were later backported from Angular to AngularJS, most of MAAS UI predated this and consequently migration to Angular would require significant app-wide refactoring.

Since the inception of the MAAS UI, a number of other products had been built at Canonical using React. As we had developed significant experience using React, and tooling in the surrounding ecosystem, ultimately it made more sense to invest in transitioning the MAAS UI to React rather than Angular. This choice conferred additional benefits, such as standardising our build and testing infrastructure, and allows for component reuse across products. We also just generally enjoy working with React, and feel that the most significant developments in web UI technology are happening within the React ecosystem (hooks, concurrent mode, suspense, CRA).