This is very much possible. Here's how you do it.
First you need to add labels to your node via your node configuration.
For a template of how this node configuration looks like, you can refer to the one in the selenium codebase here
So here's a sample node configuration file that contains the label:
{
"capabilities": [
{
"browserName": "chrome",
"applicationName":"hercules",
"maxInstances": 10,
"seleniumProtocol": "WebDriver"
}
],
"proxy": "org.openqa.grid.selenium.proxy.DefaultRemoteProxy",
"maxSession": 10
}
So here we are adding a label to the chrome browser and calling it as "hercules". This can be anything but the key always has to be applicationName
Now you start a node by passing in this node configuration file via the command line -nodeConfig. For more details on this refer to my grid tutorial here
You would now instantiate your RemoteWebDriver instance as shown below:
DesiredCapabilities caps = DesiredCapabilities.chrome();
String whichNode = System.getProperty("nodeName", "");
if (!whichNode.trim().isEmpty()) {
caps.setCapability("applicationName", whichNode);
}
RemoteWebDriver driver = new RemoteWebDriver(gridUrl, caps);
Here as you see, we are setting the same key viz., applicationName and passing in a value, if you specified something via the JVM argument -DnodeName. If you dont pass anything, the test gets routed using the default logic. If you passed in an application name, then it gets routed to the node which matches the application name.
The above doesn't require you to change anything in the selenium grid and you can use everything as is.
But if you would like something more sophisticated, then you can do so by building your own Custom capability matcher, which you would inject at the hub's end, and then work with an appropriate capability at the client side (as in the above sample code).
I created a detailed blog post about this something back. You can refer to it here for more details.
