Enter the Matrix: Selenium grid made simple
As I discussed in ‘Driver factory part 3 – Remotewebdrivers and my very own grid’ I found that it was pretty painless to set up a grid hub and node on a single Windows machine. Whilst the grid was itself perfectly stable, it is a bit of a pain to start up multiple command prompts and run individual nodes etc.
There were two obvious improvements to this that I could try:
- Work out how to configure multiple browsers on a single node.
- Use Powershell to launch hub and node from a single point.
Multiple browsers on a single hub.
It is pretty obvious that this works as it is the default configuration if you do not specify any configuration. Previously I had configured each browser on its own node requiring its own command to start it, and command window to control and log the results. I was sure I could do better.
How hard could it be?
Well as expected, it is pretty simple. In this case I am going to describe how I did it on Windows using powershell, but it would be just as simple on MacOs or linux. As a reminder, you just need the the webdriver binaries for your browsers and platform as well as the selenium standalone server jar. For convenience I put them all in ‘C:/Grid’ and I added this directory to the windows System path.
- Starting with a nodeconfig.json.
{ "capabilities": [ { "browserName": "operablink", "maxInstances": 5, "seleniumProtocol": "WebDriver", "webdriver.opera.driver": "C:/Grid/operadriver.exe" }, { "browserName": "firefox", "maxInstances": 5, "seleniumProtocol": "WebDriver", "webdriver.gecko.driver": "C:/Grid/geckodriver.exe" }, { "browserName": "chrome", "maxInstances": 5, "seleniumProtocol": "WebDriver", "webdriver.chrome.driver": "C:/Grid/chromedriver.exe" }, { "browserName": "internet explorer", "maxInstances": 5, "seleniumProtocol": "WebDriver", "webdriver.ie.driver": "C:/Grid/IEDriverServer.exe" }, { "browserName": "MicrosoftEdge", "maxInstances": 5, "seleniumProtocol": "WebDriver", "webdriver.edge.driver": "C:/Grid/MicrosoftWebDriver.exe" } ], "proxy": "org.openqa.grid.selenium.proxy.DefaultRemoteProxy", "maxSession": 5, "port": 5555, "register": true, "registerCycle": 5000, "hub": "http://localhost:4444", "nodeStatusCheckTimeout": 5000, "nodePolling": 5000, "role": "node", "unregisterIfStillDownAfter": 60000, "downPollingLimit": 2, "debug": false, "servlets" : [], "withoutServlets": [], "custom": {} }
The node launch command then becomes:
java -jar "C:\Grid\selenium-server-standalone-3.8.1.jar" -port 5560 -role node -hub http://localhost:4444/grid/register -nodeConfig "C:\Grid\nodeconfig.json"
Launch from one command
- To launch both hub and node from a single place, we can just call the commands from a 2 line powershell script
Start-Process powershell {java -jar "C:\Grid\selenium-server-standalone-3.8.1.jar" -role hub} Start-Process powershell {java -jar "C:\Grid\selenium-server-standalone-3.8.1.jar" -port 5560 -role node -hub http://localhost:4444/grid/register -nodeConfig "C:\Grid\nodeconfig.json"}
That’s all there is to it. Run the powershell script and both hub and node will launch.
Progress made this week:
- Streamlined the grid launch process into a single powershell script.
Lessons learnt:
- Launching the grid could hardly be easier.
- Opera still won’t launch on the grid despite much research and many attempts.