[🐛 Bug]: PySelenium doesn't support a named pipe as a log file

What happened?

As part of OpenWPM we use Selenium to drive multiple Firefox browsers in parallel.

To capture, enrich and redirect the browser’s logging output, we use named pipes that look like normal log files to Selenium. However pipes don’t support seeking so the need to be opened with w and not with a+ as the firefox.Service currently does. We have previously monkeypatched this but that approach has led to us breaking every time a new Selenium release comes out. A newer approach that tries to call firefox.Service.__init__ and open the log_file afterwards doesn’t work at all, so I wanted to check if there was an appetite to address this issue upstream.

How can we reproduce the issue?

import os
from selenium.webdriver import Firefox
from selenium.webdriver.firefox.service import Service
pipe_name = "selenium_pipe.log"
os.mkfifo(pipe_name, 0o600)
service=Service(executable_path="firefox",log_path=pipe_name)
driver = Firefox(
    service=service
)
driver.get("https://example.com")

Relevant log output

File "/home/vringar/selenium_mvp/demo.py", line 9, in <module>
    service=Service(executable_path="firefox",log_path=pipe_name)
File "/home/stefan/.conda/envs/openwpm/lib/python3.10/site-packages/selenium/webdriver/firefox/service.py", line 50, in __init__
    log_file = open(log_path, "a+") if log_path else None
io.UnsupportedOperation: File or stream is not seekable.

Operating System

Linux

Selenium version

Python 4.1.0

What are the browser(s) and version(s) where you see this issue?

Firefox 100

What are the browser driver(s) and version(s) where you see this issue?

GeckoDriver 0.30.0

Are you using Selenium Grid?

No response

[symonk]

Thanks @vringar seems ok to me, we could expose the mode to the user too to simplify the solution but your proposal seems ok to me too

[vringar]

Looks like you already have the code; please PR your proposed changes

Done

and discuss whatever impact it might have on existing users. We have a *lot of work planned in Python for 4.3.

I have done that in the PR. Should I do it here as well?