Pull xvfb code from vscode CI

[mrakitin]

https://github.com/microsoft/vscode/blob/ab99fbebf87c30a65d2e1152ce63afb587160a57/build/azure-pipelines/linux/continuous-build-linux.yml#L2-L9

- script: |
    set -e
    sudo apt-get update
    sudo apt-get install -y libxkbfile-dev pkg-config libsecret-1-dev libxss1 dbus xvfb libgtk-3-0
    sudo cp build/azure-pipelines/linux/xvfb.init /etc/init.d/xvfb
    sudo chmod +x /etc/init.d/xvfb
    sudo update-rc.d xvfb defaults
    sudo service xvfb start

[klauer]

Also see pydm:
https://github.com/slaclab/pydm/blob/master/azure-test-template.yml#L34

[mrakitin]

Thanks for keeping an eye on the NSLS-II kitchen, @klauer!

We are already doing this:

profile-collection-ci/azure-linux.yml

Lines 123 to 126 in 726ebc6

	# Start Xvfb
	# (from https://developercommunity.visualstudio.com/content/problem/336288/headless-testing-using-xvfb-on-hosted-ubuntu-1604.html)
	/sbin/start-stop-daemon --start --quiet --pidfile /tmp/custom_xvfb_99.pid --make-pidfile --background --exec /usr/bin/Xvfb -- :99 -ac -screen 0 1280x1024x16
	export DISPLAY=:99

However, I am not quite happy I have to do it in the same step as the test itself. I'd rather prefer to start it along with mongodb:

profile-collection-ci/azure-linux.yml

Line 86 in 726ebc6

sudo systemctl start mongodb && sudo systemctl status mongodb

but it fails to propagate to the next steps. Maybe I just need to set the DISPLAY env var: https://github.com/slaclab/pydm/blob/ea20288ba0d9a1a2022ffd33416e7b4a93bef259/azure-test-template.yml#L113-L114...

[klauer]

@mrakitin I see 😄

(I think @hhslepicka could benefit from what you decide on, so I'll ping him here.)

[hhslepicka]

You just need to set the environment for the display when you run the tests...
Check here: https://github.com/slaclab/pydm/blob/master/azure-test-template.yml#L113-L114

The export there will never work as the steps for a Azure CI job are executed in a separated shell instance.

[mrakitin]

Thanks @hhslepicka! Yes, I was burned by that at some point, but it makes sense. I'll test it using your example.

[hhslepicka]

@mrakitin it is working fine for me for a couple of months now...
Also, please not that if you are relying on events, such as focus and others, you will need a window manager.... in this case I would recommend the herbstluftwm... it is lightweight and will get you going.
Here is how I start it at my job: https://github.com/slaclab/pydm/blob/master/azure-test-template.yml#L45-L51

[mrakitin]

Neat, thanks for the suggestions, @hhslepicka! I think we are a bit far from clicking in CI, but medium- to long-term we will need that.

A side note: herbstluftwm is pretty unspellable!

[mrakitin]

@hhslepicka, are you still using herbstluftwm, or have you switched to something else?

[hhslepicka]

@mrakitin I still use that for PyDM but for some internal tasks (Youtube Streaming) I switched to using fluxbox which is smaller than herbstluftwm.

[mrakitin]

Thanks, @hhslepicka! I'll post the link you previously shared with me regarding the Youtube streaming - https://github.com/hhslepicka/docker-streaming (so I don't forget). Do you mind sharing how you use fluxbox (http://fluxbox.org)? Thank you.

[hhslepicka]

@mrakitin here is basically what I do:

# Create the Xvfb
Xvfb :101 -screen 0 1920x1080x24 -ac +extension GLX +render -noreset &
# Run fluxbox on this new display
DISPLAY=:101.0 /usr/bin/fluxbox &
DISPLAY=:101 ./start_ui &

Very similar to how Herbstluftwm is used.

[mrakitin]

Awesome, thanks!