How do I add a custom Chrome command-line argument?

[mildmojo]

I have a Python project using SeleniumBase 1.34.11 that's running inside a docker container, and I'm forwarding my pytest run to the X server on my Linux host. Unfortunately, Chrome v79 has a bug that makes it render a blank window to my host X server (nothing, no UI at all).

In the Chromium project bug report, one commenter suggests starting Chrome with --use-gl=swiftshader to enable software rendering. This works for me; I can run google-chrome --use-gl=swiftshader, and I get a regular Chome window with full UI.

I'd like to send that argument to Chrome via SeleniumBase. I've looked through the documentation and the issues in this repo, but I don't see any mention or examples of custom Chrome options. In the codebase, I see where the browser launcher's _set_chrome_options gets a ChromeOptions object and sets arguments on it, but it seems like it only understands hardcoded arguments.

Is there a way to add a custom Chrome command-line argument?

[mdmintz]

@mildmojo I'll create a new release of SeleniumBase with that option enabled. I don't see why it would hurt to have it on all the time.

[mdmintz]

@mildmojo I added the Chrome option you wanted in version 1.42.9
chrome_options.add_argument("--use-gl=swiftshader")
https://github.com/seleniumbase/SeleniumBase/releases/tag/v1.42.9

[mdmintz]

Chrome options are all set here: https://github.com/seleniumbase/SeleniumBase/blob/master/seleniumbase/core/browser_launcher.py
From the command line, you can alter some of them with pytest arguments, which are defined here: https://github.com/seleniumbase/SeleniumBase/blob/master/seleniumbase/plugins/pytest_plugin.py
If there's another option you need that isn't there, I can add that into anther release. swiftshader is now there if you upgrade to v1.42.9

[mildmojo]

That's great! Thank you for the lightning-quick feature add! 🎉

I'll see about upgrading my project on Monday.

[mildmojo]

One note, in the bug report I linked above, the commenter saw a performance penalty in their case. It might adversely affect non-headless users who have GPUs available? It could be worth leaving off by default, with like a --swiftshader option to enable it?

[mdmintz]

@mildmojo Good idea. I'll create another release using --swiftshader to enable it so that it's not on by default.

[mildmojo]

Thank you!

…

On July 10, 2020 11:20:14 PM UTC, Michael Mintz ***@***.***> wrote: @mildmojo Good idea. I'll create another release using ``--swiftshader`` to enable it so that it's not on by default. -- You are receiving this because you were mentioned. Reply to this email directly or view it on GitHub: #619 (comment)

[mdmintz]

@mildmojo See https://github.com/seleniumbase/SeleniumBase/releases/tag/v1.42.10
Now, swiftshader is only enabled when specified as a command-line option:
--swiftshader

[mildmojo]

💯💯💯

…

On July 11, 2020 1:34:38 AM UTC, Michael Mintz ***@***.***> wrote: @mildmojo See https://github.com/seleniumbase/SeleniumBase/releases/tag/v1.42.10 Now, ``swiftshader`` is only enabled when specified as a command-line option: ``--swiftshader`` -- You are receiving this because you were mentioned. Reply to this email directly or view it on GitHub: #619 (comment)

[mildmojo]

@mdmintz I had a chance to test this today, and it looks like Chrome treats the swiftshader software renderer as a GPU, which means the always-on --disable-gpu Chrome flag disables the swiftshader renderer, and I still see a blank window with the new --swiftshader option turned on.

I confirmed by capturing the full pytest/seleniumbase-composed Chrome command line in the /opt/google/chrome/chrome.real shell script, then whittling the CLI flags down to a minimal case that worked or didn't work. I'm seeing --disable-gpu --use-gl=swiftshader rendering a blank window, and --use-gl=swiftshader alone rendering a proper window. I can see swiftshader info in about:gpu when it's working, too.

Would you be willing to omit --disable-gpu when --swiftshader is specified?

[mdmintz]

@mildmojo Sounds good. I'll create a new release with the update.

[mdmintz]

@mildmojo OK, it's ready in SeleniumBase v1.42.12
https://github.com/seleniumbase/SeleniumBase/releases/tag/v1.42.12

[mildmojo]

Thanks so much, again! I'll try it out tomorrow.

[mildmojo]

@mdmintz AFAICT, the --swiftshader option (and the way it now turns off --disable-gpu) is doing the right thing, and gets me a working Chrome v79 display when forwarded to my host X server.

I also tested with dockerized Xpra and Xvfb+x11vnc+VNC setups, and while they had their own issues, Chrome rendering is fixed.

Thanks again for the quick, solid help!