Specify syntax of using existing environment variables in .env file

Issue Type: Bug

I’ve been looking at the docs and I think there needs to be some clarification, or there is a bug:

According to the docs, variables in .env file can be substituted by usage of <VARIABLE>=...${EXISTING_VARIABLE}... syntax. As I have discovered, this works for variables defined previously in the .env file, but not for system environment variables. System env variables need following syntax (tested): <VARIABLE>=...${env:EXISTING_SYSTEM_ENV_VARIABLE}...

Can you please specify how it should be, and update the docs?

Extension version: 2019.11.50794 VS Code version: Code 1.41.0 (9579eda04fdb3a9bba2750f15193e5fafe16b959, 2019-12-11T18:37:42.077Z) OS version: Windows_NT x64 10.0.18362

System Info

Item	Value
CPUs	Intel® Core™ i5-4570 CPU @ 3.20GHz (4 x 3193)
GPU Status	2d_canvas: enabled flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled metal: disabled_off multiple_raster_threads: enabled_on oop_rasterization: disabled_off protected_video_decode: unavailable_off rasterization: enabled skia_renderer: disabled_off surface_control: disabled_off surface_synchronization: enabled_on video_decode: enabled viz_display_compositor: enabled_on viz_hit_test_surface_layer: disabled_off webgl: enabled webgl2: enabled
Load (avg)	undefined
Memory (System)	15.89GB (6.49GB free)
Process Argv	L:\commonPyLibs\commonPyLibsPresentation.code-workspace
Screen Reader	no
VM	0%

[DonJayamanne]

ple windows batch script use this approach

That’s a Windows batch file scrip, not a .env file. I’m referring to just a regular .env file.

To my knowledge .env files with support for nested variables doesn’t exist in the most popular php, python and node packages (packages that support loading variables from .env files), including bash script with support for auto loading such variables. Hence my assumption about these being non-standard in .env files.

Please understand I’m not saying we should remove it. It’s a feature that exists in the extension today, and won’t be removed. I was merely expressing my opinion about this feature.

[karthiknadig]

Looks like this is a bug in the extension.

For repro this should work:

TESTVAR1=${PROCESSOR_IDENTIFIER}

ENVVAR=somevalue
TESTVAR2=${ENVVAR}

test_env.py:

import os

for i in range(1,3):
    print(f"TESTVAR{i}: " + os.getenv(f"TESTVAR{i}"))

launch.json:

{
    "name": "Python file",
    "type": "python",
    "request": "launch",
    "program": "${workspaceFolder}/test_env.py",
    "console": "integratedTerminal",
    "envFile": "${workspaceFolder}/.env"
}

expected output:

TESTVAR1: Intel64 Family 6 Model 61 Stepping 4, GenuineIntel
TESTVAR2: somevalue

actual output

TESTVAR1:
TESTVAR2: somevalue