Hi,

TL; DR Let's cut the running time of '008_basic_ui_sanity.py' by more than 3 minutes by sacrificing Firefox and Chrome screenshots in favor of Chromium.

During the OST hackathon in Brno this year, I saw an opportunity to optimize basic UI sanity tests from basic suite.
The way we currently run them, is by setting up a Selenium grid using 3 docker containers, with a dedicated network... that's insanity! (pun intended).
Let's a look at the running time of '008_basic_ui_sanity.py' scenario (https://jenkins.ovirt.org/view/oVirt%20system%20tests/job/ovirt-system-tests_manual/4197/):

01:31:50 @ Run test: 008_basic_ui_sanity.py: 01:31:50 nose.config: INFO: Ignoring files matching ['^\\.', '^_', '^setup\\.py$']01:31:50 # init: 01:31:50 # init: Success (in 0:00:00)01:31:50 # start_grid: 01:34:05 # start_grid: Success (in 0:02:15)01:34:05 # initialize_chrome: 01:34:18 # initialize_chrome: Success (in 0:00:13)01:34:18 # login: 01:34:27 # login: Success (in 0:00:08)01:34:27 # left_nav: 01:34:45 # left_nav: Success (in 0:00:18)01:34:45 # close_driver: 01:34:46 # close_driver: Success (in 0:00:00)01:34:46 # initialize_firefox: 01:35:02 # initialize_firefox: Success (in 0:00:16)01:35:02 # login: 01:35:11 # login: Success (in 0:00:08)01:35:11 # left_nav: 01:35:29 # left_nav: Success (in 0:00:18)01:35:29 # cleanup: 01:35:36 # cleanup: Success (in 0:00:06)01:35:36 # Results located at /dev/shm/ost/deployment-basic-suite-master/008_basic_ui_sanity.py.junit.xml01:35:36 @ Run test: 008_basic_ui_sanity.py: Success (in 0:03:45)

Starting the Selenium grid takes 2:15 out of 3:35 of total running time!

I've investigated a lot of approaches and came up with something like this:

install 'chromium-headless' package on engine VM
download 'chromedriver' and 'selenium hub' jar and deploy them in '/var/opt/' on engine's VM
run 'selenium.jar' on engine VM from '008_basic_ui_sanity.py' by using Lago's ssh
connect to the Selenium instance running on the engine in '008_basic_ui_sanity.py'
make screenshots

This series of patches represent the changes: https://gerrit.ovirt.org/#/q/topic:selenium-on-engine+(status:open+OR+status:merged).
This is the new running time (https://jenkins.ovirt.org/view/oVirt system tests/job/ovirt-system-tests_manual/4195/):

20:13:26 @ Run test: 008_basic_ui_sanity.py: 20:13:26 nose.config: INFO: Ignoring files matching ['^\\.', '^_', '^setup\\.py$']20:13:26 # init: 20:13:26 # init: Success (in 0:00:00)20:13:26 # make_screenshots: 20:13:27 * Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7fdb6004f8d0>: Failed to establish a new connection: [Errno 111] Connection refused',)': /wd/hub20:13:27 * Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7fdb6004fa10>: Failed to establish a new connection: [Errno 111] Connection refused',)': /wd/hub20:13:27 * Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7fdb6004fb50>: Failed to establish a new connection: [Errno 111] Connection refused',)': /wd/hub20:13:28 * Redirecting http://192.168.201.4:4444/wd/hub -> http://192.168.201.4:4444/wd/hub/static/resource/hub.html20:14:02 # make_screenshots: Success (in 0:00:35)20:14:02 # Results located at /dev/shm/ost/deployment-basic-suite-master/008_basic_ui_sanity.py.junit.xml20:14:02 @ Run test: 008_basic_ui_sanity.py: Success (in 0:00:35)

(The 'NewConnectionErrors' is waiting for Selenium hub to be up and running, I can silence these later).
And the screenshots are here: https://jenkins.ovirt.org/view/oVirt%20system%20tests/job/ovirt-system-tests_manual/4195/artifact/exported-artifacts/screenshots/

The pros:

we cut the running time by more than 3 minutes

The cons:

we don't get Firefox or Chrome screenshots - we get Chromium screenshots (although AFAIK, QE has much more Selenium tests which cover both Firefox and Chrome)
we polute the engine VM with 'chromium-headless' package and deps (in total: 'chromium-headless', 'chromium-common', 'flac-libs' and 'minizip'), although we can remove these after the tests

Some design choices explained:

Q: Why engine VM?

A: Because the engine VM already has 'X11' libs. We could install 'chromium-headless' (and even other browsers) on our Jenkins executors, but that would mess them up a lot.

Q: Why Chromium?

A: Because it has a separate 'headless' package.

Q: Why not use 'chromedriver' RPM in favor of https://chromedriver.storage.googleapis.com Chromedriver builds?

A: Because the RPM version pulls a lot of extra dependencies even on the engine VM ('gtk3', 'cairo' etc.). Builds from the URL are the offical Google Chromedriver builds, they contain a single binary, and they work for us.

What still needs to be polished with the patches:

Currently 'setup_engine_selenium.sh' script downloads each time 'selenium.jar' and 'chromedriver.zip' (even with these downloads we get much faster set-up times) - we should bake these into the engine VM image template.
'selenium_hub_running' function in 'selenium_on_engine.py' is hackish - an ability to run an ssh command with a context manager (and auto-terminate on it exits) should be part of Lago. Can be refactored.

Questions, comments, reviews are welcome.

Regards, Marcin