How to identify which version of Yarn is used by a project?

Question

For the OSS Review Toolkit project, I would like to identify which version of yarn is used by a given project in a given repository.

Which criteria should be used ? There is:

• package.json/packageManager which requires Corepack and may not be used by all projects.
• look at the version .yarn/releases/*
• check the .yarnrc file: if this is yarnrc.yml then this is Yarn 2+.
• the version in yarn.lock seems to not be related to the Yarn version used for the project (but please correct me if I am wrong).

Is there any other criteria that could be used to disambiguiate if this is a Yarn 1, 2 or 3 project ?

Answer 1

In my experience, it shows the version of yarn being run when you perform a yarn command (e.g. yarn install) on a repository.

Answer 2

The frustrating answer is that there isn't an easy way (although there probably should be). Running yarn -v will simply show your global yarn version; not the local repo. You need to look for the same hints you listed.

Perhaps your collaborators can agree to make an arbitrary .yarnver file that simply contains something like:

1.22.11