How to debug Docker containers! (Python + VSCode)

I recently encountered an issue where a python unit test was passing inside of a container, but failing locally.

In this video I show a few different tips/techniques for debugging code running within a docker container:

1) Modify the container entrypoint and exec into the container
2) Copy files to and from the container for inspection/comparison
3) Set up a remote debugger inside the container and attach to it from the host

I hope you find these helpful as you debug your own containerized applications.

Cheers!

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Timestamps:
0:00 - Intro
0:57 - Sample test case overview
1:12 - Sample Dockerfile
2:28 - Tip #1 (modify entrypoint)
4:00 - Tip #2 (docker cp)
5:39 - Tip #3 (remote debugger)
7:16 - Configuring debugger in VSCode
8:54 - Closing thoughts

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Community Size at Time of Posting:
- Subscribers: 225 🎉
- Channel Views: 3715

[datamike]

Nice video. I've been exploring docker containers and the extra abstraction makes debugging more awkward. This was super helpful!

[TuomoKankaanpaa]

Wow the remote debugger and attaching it to vs code will really come in handy! And congrats on the 200 subs 🙌🎉

[AZIARGROUS]

Thank you man! This is exactly the kind of concept I was playing with these days. Thank you for explaining how to expose that port from docker to local host.

[kab]

Thanks for the best and the clearest tutorial on how to debug python into Docker with VSC !

[thebluechimera]

Great video! I've always found Docker quite intimidating, this was good to watch

[akozy]

This is what I was looking for!!! It seemed so hard to find for some reason. Can't wait to see your channel grow. Keep it up!

[machinelearningid]

From traversy, thanks, your devops video are awesome.

[eddydewaegeneer]

I would like to see a tutorial that describes how to debug python code mapped from outside the docker (using the -v parameter)but running inside a container for which I have only the container (and not the Dockerfile)

[kid_kulafu_]

Who’s here because you saw this dude on brads channel? Thank you for this sir.

[plashless]

This is really amazing.
I'm having a use case would really appreciate for helping me out. :)

I'm running services in Docker Containers i-e web, db, worker(celery).
Is there any way so that I can add a breakpoint in the Pycharm(code) and it will start the debugger in the containers(specifically celery worker)?

[ShikhaSingh]

Can you suggest any other dependency for debugging else than debugpy?

[bqdofoq]

I have my dockerfile made and Im using fastapi python but when I run my application via that play button of VSCODE I run into a error called PYTHON PATH IN YOUR DEBUG CONFIGURATION IS INVALID.
please help me with that
..

[yuriwolf]

Dear Sid,
do I have to rebuild the docker image every time I modify something in my .py file?
thanks
regards

[uncoding_with_raj]

Can we connect VSCODE debugger AUTOMATICALLY to docker container without hitting the play button in VSCODE ?

[jansoriano]

Hi Sid, I've seen your video tutorial on Brads channel. I'm currently a shopify dev, and I want to become a devops engineer. I am hoping to get tips from you or your channel. Thanks!

[danh_phuong]

That's great. I'm looking for debugging C in docker with VSCode. Please suggest any solution !!!

[nareshmp]

Nice video. Is it possible to debug the code step by step? Especially when its web2py app?