Selenium grid - node configuration file for Firefox not reading moz:firefoxOptions - selenium

Question

I have setup my selenium grid (currently 1 hub and 1 node).
The hub is working fine but for my node I setup the below configuration file (nodeconfig.json)
I wanted to start the firefox in headless mode but it looks like the "moz:firefoxOptions" configuration did not catch up.
I tried setting the "moz:firefoxOptions" in a variety of location in side the json file without any luck :( .
I are using :
windows server 2016 64bit ,
selenium-server-standalone 3.9.1
geckodriver v0.19.1
firefox v59.0
we are running the node using the following command :
java -Dwebdriver.gecko.driver="geckodriver.exe" -Dwebdriver.chrome.driver="chromedriver.exe" -jar selenium-server-standalone-3.9.1.jar -role node -nodeConfig nodeconfig.json
I can tell that the configuration file was read as I can see it in the selenium grid console.
nodeconfig.json file:
{
"capabilities": [
{
"browserName": "firefox",
"maxInstances": 5,
"seleniumProtocol": "WebDriver",
"alwaysMatch": {
"moz:firefoxOptions": {
"args": [
"-headless"
]
}
}
},
{
"browserName": "chrome",
"maxInstances": 5,
"seleniumProtocol": "WebDriver"
}
],
"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": {}
}
In addition from the logs I can tell that the argument is not added.
The relevant line is :
1520854660258 mozrunner::runner INFO Running command: "C:\Program Files\Mozilla Firefox\firefox.exe" "-marionette" "-profile" "C:\Users\avi\AppData\Local\Temp\rust_mozprofile.03tQm3hduVDR"

Answer 1

As per the documentation the argument is --headless not -headless. So possibly you have to change to :
"moz:firefoxOptions": {
"args": [
"--headless"
]
}
You can find a detailed discussion in How to make firefox headless programatically in Selenium with python?