With the release of Composer 2, you might want to use it in your PHP application.
Platform.sh PHP images ship with Composer 1.
Since you can declare additional dependencies via your
.platform.app.yaml, Composer 2 can be required like this:
dependencies: php: composer/composer: '^2.0'
After you commit and push your changes, with the next build and redeploy, the application container will get Composer 2 (both during build and runtime):
email@example.com:~$ composer --version Composer 2.0.2 2020-10-25 23:03:59