env var name CAN be any unicode char, not just ASCII

[ndeloof]

make godotenv use runes, not byte to process dot env text file, so we support unicode in variable names

closes #277

[glours]

LGTM

[milas]

👍🏻

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From Open Group Base Spec:

Environment variable names used by the utilities in the Shell and Utilities volume of POSIX.1-2017 consist solely of uppercase letters, digits, and the ( '_' ) from the characters defined in Portable Character Set and do not begin with a digit. Other characters may be permitted by an implementation; applications shall tolerate the presence of such names.

N.B. "Portable character set" is a subset of ASCII-encodable characters

So, much like we also accept other characters (., -), don't see any reason to not allow full Unicode!

[milas]

Missed opportunity for an emoji in a test case 🤌

[milas]

oh boo, we still check to see if it's considered a letter:

failed to read /Users/milas/dev/repro/unicode/.env: line 1: unexpected character "😂" in variable name

[milas]

but also...

$ docker compose run echo
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
HOSTNAME=5fadb26ba525
TERM=xterm
😂=1
HOME=/root

surprise! we do something different for env vars in YAML 🙈

services:
  echo:
   environment:
     - "😂=1"
   image: alpine
   command: env

[ndeloof]

While there's POSIX docs about supported formats, we should align with docker run so that users don't get strange behaviour using compose

$ docker run -e 😂=1 alpine env
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
HOSTNAME=78568bfa2fcd
😂=1
HOME=/root

so we have to relax the rule...

[milas]

Agreed re: aligning with docker run! Sorry if my spec quoting was unclear -- it says that for interoperability with POSIX-y tools you should stick to ~ASCII, but that it's not prohibited from using other characters

I think it's more of a warning that lots of those tools were built in the 70s and don't have any concept of UTF-8 😬

But regardless, totally fine -- at the end of the day, if you pass Unicode env var names to your Compose service and it can't handle that...don't do that? 🤷🏻