These were the opening slides used in the all-day Selenium Grid Workshop, given by Marcus Merrell and Manoj Kumar on November 14, 2016 at the 2016 London Selenium Conference

1. Selenium Grid Workshop

2. Schedule
9:00-9:30 — General Set up: Power Cords, Wi-Fi, Seating, and Introductions
9:30-10:30 — Grid Overview, Basic Concepts & Philosophy
10:30-10:45 — Break
10:45-12:00 — Hub/Node Setup and Config
12:00-1:00 — Lunch
1:30-3:30 — Docker, Troubleshooting, and Advanced Options
3:30-3:45 — Break
3:45-5:00 — Extensions, Plug-ins, Auto-scaling, and Advanced Logging
— Q&A, Anecdotes, Discussion, and General Tips & Tricks

3. Overview
● Terminology
● General Flow
● Hub/Node Details
● Configuration
● Docker Intro
● Edge (if you dare)
● Preview of Next Session
https://goo.gl/BWlK1a

4. Terminology
● Hub
● Node
● Test Slot
● Test
● Thread
● Proxy

5. Grid 101

6. Hub
● The intermediary and manager
● Accepts requests to run tests
● Allocates Test Slots to nodes
● Takes instructions directly from client, and executes them
remotely on nodes
● The Hub only manages threads—it performs zero browser
work

7. Node
- Registers itself to Hub listed in config
- Communicates its config to the Hub at registration time:
- Test Slots per browser
- “Hey Hub, I have 1 Slot for Firefox, 5 for Chrome”
- Receives json wire protocol instructions from the Hub
- Executes instructions, keeping threads separated
- The Node does not evaluate, make judgments, or control
anything: it only receives and executes instructions (and
throws exceptions)

8. Start the Hub:
java -jar selenium-server-standalone-3.0.1.jar -role hub
Register a node:
java -jar selenium-server-standalone-3.0.1.jar -role node
-hub http://localhost:4444/grid/register -browser
browserName=firefox,maxInstances=3 -browser
browserName=chrome,maxInstances=5
*All commands are case sensitive!
Starting From Command-line

9. Hub Parameters — Configuration
● -port
Default is 4444, use this to override
● -jettyMaxThreads <int>
Maximum number of threads server will pool
● -cleanUpCycle <milliseconds>
Interval for hub to poll for inactive test sessions

10. Hub Parameters - Timeouts
● -timeout <seconds>
● -browserTimeout <seconds, min 60>
Timeout between receiving individual commands
60 seconds minimum value
● -newSessionWaitTimeout <milliseconds>
Timeout the server will wait for a new Session to be created

11. Hub Parameters —
● -prioritizer
Class (on the classpath!) that will be used to sort queued new Session requests
Must implement Prioritizer
● -servlets
Custom servlets, mainly for grid plugins
● -log <filename>

12. Hub Parameters — Capabilities
● -throwOnCapabilityNotPresent
● -capabilityMatcher
Class that implements CapabilityMatcher
DefaultCapabilityMatcher only checks Platform, Browser Name, Version,
“applicationName”

13. Node Command line options
● -nodeConfig <filename>
● -hubHost <DNS entry>
● -hubPort <port>
● -host <localhost>
● -port <local port>
● -maxSession <int>
● -register
● -servlets

14. Node Parameters — JSON file
● -nodeConfig <filename>
{ "capabilities": [
{ "browserName": "chrome",
"maxInstances": 5,
"platform": "WINDOWS",
"webdriver.chrome.driver": "C:/Program Files (x86)/Google/Chrome/Application/chrome.exe" }, ],
"configuration": {
"_comment" : "Configuration for Node",
"cleanUpCycle": 2000,
"proxy": "org.openqa.grid.selenium.proxy.WebDriverRemoteProxy",
"port": 5555,
"host": ip,
"register": true,
"hubPort": 4444,
"maxSessions": 5 }
}

15. Node Command line options
● -browser param1=val1,param2=val2
Usually, only browserName, platform, version, applicationName and
maxInstances are important
● -cleanUpCycle <milliseconds>
● -registerCycle <milliseconds>
How often the node will try to register itself again. Allows you to restart the hub
without having to restart the nodes

16. Run It!
● We’ll write a quick javascript test
● Use node to run it
● We’ll need:
○ Node (v6.9.0) (brew install node)
○ selenium-webdriver module (npm install -g selenium-webdriver)
○ chromedriver v2.25.426935
● Paste script (https://goo.gl/sRNVVC) into test.js
● node test.js
● It will go really fast, so be sure to watch!

17. docker 101
● docker ps
● docker exec -it <container id> bash
● docker kill <image>
● docker run
● docker images -a
● docker rmi <image>
● docker -p
● docker -P
● docker -d
● docker --link

18. docker-selenium Standalone
Running a standalone machine without connecting to a hub
● selenium/standalone-chrome: Selenium standalone with Chrome installed
● selenium/standalone-firefox: Selenium standalone with Firefox installed
● selenium/standalone-chrome-debug: Selenium standalone with Chrome
installed and runs a VNC server
● selenium/standalone-firefox-debug: Selenium standalone with Firefox installed
and runs a VNC server

19. docker-selenium Standalone
Start docker instance:
Chrome docker run -d -p 4455:4444 selenium/standalone-chrome:2.53.0
Firefox docker run -d -p 4466:4444 selenium/standalone-firefox:2.53.0
docker run -d --name se -p 5900:5900 -p 4444:4444
selenium/standalone-chrome-debug
Check they are up and running and you can connect to them!
http://localhost:4455/wd/hub/status
http://localhost:4466/wd/hub/status
Register them to your running hub: https://goo.gl/TE4xuv

20. docker-selenium GRID
● selenium/hub: Image for running a Selenium Grid Hub
● selenium/node-chrome: Selenium node with Chrome installed, needs to
be connected to a Selenium Grid Hub
● selenium/node-firefox: Selenium node with Firefox installed, needs to be
connected to a Selenium Grid Hub
● selenium/node-chrome-debug: Selenium node with Chrome installed
and runs a VNC server, needs to be connected to a Selenium Grid Hub
● selenium/node-firefox-debug: Selenium node with Firefox installed and
runs a VNC server, needs to be connected to a Selenium Grid Hub

21. docker-selenium GRID
● Creating a docker HUB instance
docker run -d -p 5000:4444 --name selenium-hub -P selenium/hub
To check if the hub is up and running
http://localhost:5000/grid/console
● Run a Chrome Node and Link it to Hub
docker run -d --link selenium-hub:hub -P --name chrome
selenium/node-chrome-debug
● Run a Firefox Node and Link it to Hub
docker run -d --link selenium-hub:hub -P --name firefox
selenium/node-firefox-debug

22. Selenium GRID with docker-compose
docker-compose is a YAML file that will help manage your docker services
● Start, stop & rebuild services
● View the status and logs of services.
To get a docker-compose yml file: https://goo.gl/puYvnV
To spin up Selenium Grid: docker-compose up -d

23. Q&A
Thank You All!
Marcus Merrell
&
Manoj Kumar

24. Add a Windows VM https://goo.gl/P8q7jT

25. starting Edge node
java -jar
selenium-standalone-server-3.0.1.jar
-nodeConfig config.json -port 4444 -hub
http://<host>:<port>/grid/register -host <ip
address of win10 vm> -role node
config file:
https://goo.gl/LWdsGm

26. Other Grid Topics
Selenium Grid Extras
https://github.com/groupon/Selenium-Grid-Extras
Selenium Grid Scaler
https://github.com/mhardin/SeleniumGridScaler
BrowserMob Proxy
https://bmp.lightbody.net/

27. Run Via Saucelabs
java
> -cp
> selenium-server-standalone-3.0.1.jar;
> sauce-grid-plugin-1.0.4.jar
> org.openqa.grid.selenium.GridLauncher
> -role hub
> -servlets
> com.saucelabs.grid.SauceOnDemandAdminServlet,
> com.saucelabs.grid.SauceOnDemandConsoleServlet