Document how to debug locally w/ popular IDEs

[di]

Create well-structured documentation about debugging functions locally with popular IDEs:

• PyCharm
• VSCode
• others?

Originally posted by @yuri-sergiichuk in #29 (comment)

[ChristianSauer]

I think this is a very important topic - it confused me massivley at the beginning.
As a problem: Even now I am unable to disable the debugger --debugger False does not work, and it seems to be active per default.

[di]

@ChristianSauer, can you file a separate issue with more details? I think I know what's happening but want to confirm.

[jduplessis]

I think this would be very helpful. I'm burning quite some time trying to figure out how to debug function-framework running in a container. It eventually led me to look into Python remote debugging on VSCode in general.

I found some great material on this by @marcel-dempers. Trying to convert it to something I can use with functions-framework has however not proven successful (...yet), mainly due to this:

I would really appreciate any pointers to existing material that could help.

[di]

@jduplessis Could you link to the guide you've tried to use so far?

[jduplessis]

I started off with this which enabled me to debug a Flask app running in a container. I then attempted to replace the flask "overhead" with functions-framework, but I haven't been able to hit a break point yet.

I made small changes to the code above, mainly trying to get something like this working:

This is what I have thus-far: https://github.com/jduplessis/getting_there

*Disclaimer: My "Python" isn't that great

[di]

It's possible that we might need to make some changes to the framework to support using ptvsd.

Would you be able to try installing the framework from this branch and see if you're able to hit a breakpoint?

You can install it from there by making this change to your Dockerfile:

- RUN pip install gunicorn functions-framework
+ RUN pip install git+https://github.com/GoogleCloudPlatform/functions-framework-python@cloud-debugger

EDIT: Actually, you won't have git installed in that base image, you'll need to do:

FROM python3.7.3-slim

RUN apt-get update
RUN apt-get install -y git

as well.

[jduplessis]

When I attach the debugger, I get this (which looks promising):

But then I run into this:

[di]

Hmm, any idea where it's getting the 45397 port from? That doesn't seem to be described at https://code.visualstudio.com/docs/containers/debug-python, just the ptvsd port.

[jduplessis]

I have no idea. The port in the error message changes every time I attach the debugger. I'm looking into a similar issue reported here: microsoft/ptvsd#1560.

[di]

Ah, that seems to make sense. Can you try:

- CMD python -m ptvsd --host 0.0.0.0 --port 5678 --wait --multiprocess -m functions_framework --target hello --debug --port 8080
+ CMD python -m ptvsd --host 0.0.0.0 --port 5678 --wait --multiprocess -m functions_framework --target hello --port 8080

[jduplessis]

When I remove --debug I get a lot of errors in the container, but this focused my attention on --multiprocess. Removing the --multiprocess resolved the random port issue.

Still no luck with the break point:

EDIT:
Removing only --debug resulted in this, but I'm not able to get a request through on 8080 anymore.

[di]

Thanks. It's very likely this is due to how the framework loads user code and additional work on your part won't resolve it. I will plan to take a closer look at this soon.

[jduplessis]

Thanks @di. I'll stick to functions-framework on local for now.