N/A

in the deployment:

If I am not mistaken, a shared variable can't reference a service variable. What you want to do is to reference the postgres DATABASE_URL directly in another service.

What can shared variables reference?

or is this ${{REF}} placeholder not supposed to be here 👀

From what I observe, shared variables can reference shared variables. This may be useful if you want to create a new shared variable that is constructed with (an) existing shared variable(s).

!s