How to get Netlify to use yarn if there is no yarn.lock file?

I guess I missed them because I didn’t really know what I had to find.

It’s more about the context. The path I had to follow to get to a solution got me to read tens of comments in 2 - 3 github issues in the netlify/build-image repo, then jumping to the docs that directly links to a particular section where env vars aren’t shown. Then I reached to the Netlify forums from a Google search, reading a couple of other users related questions…

It’s in one of these answers I got these variables Issues with build.ignore command not ignoring as required - #13 by luke

So, the info is there but the search path is not really straightforward like reading the entire documentation carefully. I don’t know what could be done to help find things more easily.

Anyway thanks again : ))