In this article we will learn how to dual boot any composer app (like a Yii2 app) in a local environment and continuous integration (CI) service. This can be used to upgrade the version of Composer, PHP, or even maybe Yii, along the way with normal development, even if it's a process that spans many weeks or months.
This is inspired by Jordan Raine's talk about Clio's process to upgrade Rails over the years (You can watch it over here: Ten Years of Yii Upgrades), this post by Ernesto Tagwerker, and my own experiences about doing this on the Kantox B2B Forex Fintech platform.
First, we need to initialize the composer-next.json
file like this: