expansion modifiers block inherited values on merge

[rsgalloway]

if I have an app.env file like:

include: [default]
all: &all
 API_KEY: ${API_KEY}

and a secrets.env like:

include: [default]
all: &all
  API_KEY: !base64 c2VjcmV0

and a prod.env file like:

include: [default, secrets, app]

resolving API_KEY in prod works:

$ envstack prod -r API_KEY
API_KEY=secret

but not when writing it back out:

$ envstack prod -o out.env
$ ./out.env -r API_KEY
API_KEY=

this appears to be because the ${API_KEY} value in app.env overrides the value in secrets.env when merging. if I put secrets after app then it merges correctly, but since the value in app.env is an expansion modifier I would expect it to inherit the value from secrets just like when resolving.

[rsgalloway]

I added the question label, because maybe it's not 100% clear what should happen in this case. also you can get the value to export if you use the --resolve option:

$ envstack prod -o out.env -r
$ ./out.env -r API_KEY
API_KEY=secret