Improve handling of environment variables in the pipe transformer

[Hoeze]

From https://github.com/projectglow/glow/blob/master/docs/source/tertiary/pipe-transformer.rst:

Options beginning with env_ are interpreted as environment variables. Like other options, the environment variable name is converted to lower snake case. For example, providing the option env_aniMal=MONKEY results in an environment variable with key ani_mal and value MONKEY being provided to the piped program.

Would it be possible to have some argument jsonEnv that can decode json-encoded environment variables?
E.g.:

jsonEnv='{"PATH": "/usr/bin"}'

This would make it significantly easier to adjust environment variables IMHO.

[Hoeze]

The snake-case parsing of arguments makes it impossible to pass uppercase environment variables, right?
E.g. env_TEST would get translated to t_e_s_t.

Interestingly, passing env_test_path='asdf' results in an environment variable test_path="asdf".
So actually there is no need to parse them as snake-case.

[williambrandler]

An alternative approach is to define environment variables via JSON and put those variables into your script, which is then run through the pipe transformer.

Here's an example,

I have never used the environment variable feature in glow. Probably because I hit the same limitations you describe above!

[Hoeze]

Ah, OK, I did not think of that solution 😁

[williambrandler]

will keep the issue open for now until this is properly documented

should delete those environment variable options from the docs, they are somewhat confusing

[williambrandler]

updating the example in the docs to avoid this issue in future:

#490