Python Debugger is overiding PYTHONPATH

[tkuraku]

Environment data

• VS Code version: 1.27.1
• Extension version (available under the Extensions sidebar): 2018.8.0
• OS and version: Windows 7
• Python version (& distribution if applicable, e.g. Anaconda): Anaconda 5.2

Actual behavior

When I debug a python file in vscode my PYTHONPATH variable is overridden.

here is the relevant line shown on the terminal.

set "PYTHONPATH=c:\Users\username.vscode\extensions\ms-python.python-2018.8.0\pythonFiles\experimental\ptvsd"

Expected behavior

I would expect the PYTHONPATH to be appended to not overridden.

Steps to reproduce:

1. Set the PYTHONPATH variable to something
2. debug a script with the follow code:

import sys
print(sys.path)

You should not see the path that you set in the PYTHONPATH

[brettcannon]

I can't remember if we supported this in the old debugger (if we did then this is a regression). Otherwise I think of any reason off the top of my head to not append PYTHONPATH as appropriate.

[tkuraku]

Thank you for the quick reply. Hopefully this can be resolved.
If someone's python script/program relies on the PYTHONPATH being set then the current behavior of the debugger makes it unusable.

[DonJayamanne]

@tkuraku
Please could you confirm you have a value in PYTHONPATH?

[tkuraku]

@DonJayamanne
I do have a value in PYHTONPATH. The reason I noticed this was that when I run my script from the terminal everything works as expected. However, when I ran the debugger my script failed with an import error on one of my modules that is in the PYTHONPATH. (FYI debugger works fine in pycharm).

[Argysh]

I'm having the same issue and it used to work a couple of days ago.
(vscode was updated to 1.26.1 in between.)

running my script in either ipython or python in the terminal works as expected. when running the debugger with these settings

        {
            "name": "Python: Current File",
            "type": "python",
            "request": "launch",
            "program": "${file}"
        },

shows that the PYTHONPATH is being overwritten to
"PYTHONPATH=/home/myname/.vscode/extensions/ms-python.python-2018.8.0/pythonFiles/experimental/ptvsd"

[Argysh]

adding individual softlinks to /home/myname/.vscode/extensions/ms-python.python-2018.8.0/pythonFiles/experimental/ptvsd to the required modules works for me as a temporary work-around

ln - s /home/path/to/my/module /home/myname/.vscode/extensions/ms-python.python-2018.8.0/pythonFiles/experimental/ptvsd/

[DonJayamanne]

@Argysh @tkuraku
Is PYTHONPATH defined in your python environment or is it a global environment variable?

[DonJayamanne]

I believe the solution is not to invoke PTVSD as a package, but to run a python file that'll launch PTVSD with the path setup (e.g. sys.path.append.... or similar).

@brettcannon changing labels as this is a break from previous (old debugger) behavior.

[tkuraku]

My PYTHONPATH is a global environment variable. I think that once the script has started that anything added with sys.path.append is fine.

[DonJayamanne]

@brettcannon
We are appending PTVSD to the exiting PYTHONPATH. However it looks like we're not getting the value inside the extension process. Could be related to #2363, #1403, and others

[brettcannon]

@DonJayamanne are we running a separate process to get PYTHONPATH instead of just querying the environment that Node has in the extension itself?

[DonJayamanne]

are we running a separate process to get PYTHONPATH instead of just querying the

No we aren't running a separate process.
We just query the environment that node has in the extension.

[Argysh]

My PYTHONPATH is a global environment variable as well (set in .bashrc)

[dmitriyrepin]

After the recent upgrade, I have noticed the same issue on Linux (CentOS 7, Python 3.4, VS Code Version 1.12.1)

1. $PYTHONPATH is defined as a global (bash) environment variable before starting a VS Code from the command line.

2. VS Code picks it up. PYTHONPATH value can be observed in the VS Code terminal window

sh-4.2$ echo $PYTHONPATH
/host/viz-json-service/src/code:/host/viz-json-service/src/generated:/host/viz-json-service/src/tests

3. Here is my launch.json:

        {
            "name": "Python: run_tests.py",
            "type": "python",
            "request": "launch",
            "program": "${workspaceFolder}/src/run_tests.py",
            "console": "integratedTerminal",
        }

4. However, when I start debugger (F5), the PYTHONPATH is overwritten:

sh-4.2$ cd /host/viz-json-service ; env "PYTHONIOENCODING=UTF-8" "PYTHONUNBUFFERED=1" "PYTHONPATH=/headless/.vscode/extensions/ms-python.python-2018.8.0/pythonFiles/experimental/ptvsd" /usr/bin/python3 -m ptvsd --host localhost --port 46405 /host/viz-json-service/src/main.py

5. As a result, a package fails to load

Exception has occurred: ImportError
No module named 'code.viz_json'; 'code' is not a package
  File "/host/viz-json-service/src/tests/viz_json/test_util.py", line 6, in <module>

The same code run from a command line works fine:

$ python3 src/run_tests.py 
test_py_zgy (test_py_zgy.TestUtils) ... ok

6. the code structure is as following:

root/
     code\
         __init__.py
        viz_json\
             __init__.py
             util.py
    tests\
       ....

--
...

[brettcannon]

@dmitriyrepin FYI that the terminal in VS Code is a fresh terminal and shell (i.e. a separate process and such), so the fact the terminal picks up PYTHONPATH does not necessarily correlate that VS Code itself picked it up.

[dmitriyrepin]

FYI: I re-installed VS Code 1.26.1 + plugins in my container - same issue.
However, after installing VS Code 1.24.1 everything works as expected (so, the issue is a regression - it used to work with the old debugger):
sh-4.2$ cd /host/viz-json-service ; env "PYTHONIOENCODING=UTF-8" "PYTHONUNBUFFERED=1" /usr/bin/python3 /headless/.vscode/extensions/ms-python.python-2018.6.0/pythonFiles/PythonTools/visualstudio_py_launcher.py /host/viz-json-service 46428 34806ad9-833a-4524-8cd6-18ca4aa74f14 RedirectOutput,RedirectOutput /host/viz-json-service/src/run_tests.py

[Hareis]

Yes, I try to roll back to before version, i can start debugging code

[ericsnowcurrently]

I was able to verify that my PYTHONPATH env var shows up in sys.path in a debugged program.