dotenv-expand breaking build when "$" is used

[jdcrensh]

We use variables that include $ within the strings, which we don't want to be expanded. Escaping with \$ works fine when it occurs at the start of the string, but not anywhere else within the string.

Example:

REACT_APP_MYVAR=\$bar.baz <- works as expected, value is "$bar.baz"
REACT_APP_MYVAR=foo\$bar.baz <- I'd expect "foo$bar.baz" but I get "foo\.baz"

I also tried working around the problem, like so:

BAR=\$bar
REACT_APP_MYVAR=foo$BAR.baz

But it gave the same result of "foo\.baz"

[gaearon]

This sounds really annoying. Sorry.

Do you want to look into what's causing this?

[iansu]

This does appear to be a bug in dotenv-expand. It only looks for an escaped $ at the start of the string.

[jdcrensh]

Right, it looks like this is the problem: https://github.com/motdotla/dotenv-expand/blob/master/lib/main.js#L25

[iansu]

Yes. I think there a couple of ways to fix it:

1. Only expand when the variable starts with $ (instead of when it doesn't start with \$). This would make it impossible to expand variables inside a string which is maybe okay.
2. Check if each occurrence of $ in the string is escaped and only expand it if it's not

[gaearon]

Check if each occurrence of $ in the string is escaped and only expand it if it's not

This makes sense to me. We should also document that behavior.

[gaearon]

Fixed in react-scripts@1.1.1.