Docker ports shadow local ones and can cause bugs

This is part of the Semicolon&Sons Code Diary - consisting of lessons learned on the job. You're in the containerization category.

Last Updated: 2025-01-18

I had the error "unable to connect to chromedriver 127.0.0.1:9515"

I went online and Googled for generic (and useless info)

Ultimately I should have inspected what was going on in my computer at that port

and I'd have seen that a stray docker instance was there.

Lessons

Stop docker on your host system if something else has broken.
When you cannot connect to a port, use command line tools to inspect what is happening there (e.g. $ lsof -i :80)

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