How do you setup an HtmlUnit node with Selenium Grid? - selenium

Question

I'm having trouble setting up an HtmlUnit node with Selenium Grid.
I'm launching my Hub with:
java -jar selenium-server-standalone.jar -role hub -port 4444
And HtmlUnitDriver nodes with:
java -jar selenium-server-standalone.jar -role node -browser browserName=htmlunit,maxInstances=5 -hub http://localhost:4444/grid/register -port 5564
My code to connect to the node, which is getting the exception, looks something like:
DesiredCapabilities cap = new DesiredCapabilities();
cap.setBrowserName("htmlunit");
cap.setJavascriptEnabled(false);
driver = new RemoteWebDriver(new URL("http://localhost:4444/wd/hub"), cap);
The exception I'm getting is:
Unable to create session from {
"desiredCapabilities": {
"browserName": "htmlunit",
"server:CONFIG_UUID": "93a0486d-c9f6-46da-8065-603ab07c0294",
"javascriptEnabled": false
},
"capabilities": {
"firstMatch": [
{
"browserName": "htmlunit",
"server:CONFIG_UUID": "93a0486d-c9f6-46da-8065-603ab07c0294"
}
]
}
}

Answer 1

To set up a Selenium Grid instance, I use the Selenium Foundation library. The "standalone" JAR brings in scads of transitive dependencies you don't need that end up creating conflicts. I created a sample project (local-grid-utility) that launches a Selenium 2 Grid that dispenses PhantomJS sessions, which could be easily altered to launch a Selenium 3 Grid dispensing HtmlUnit sessions.
The key to getting HtmlUnit sessions stood up in Grid is providing a complete class path that includes all of the dependencies. Here's what the library assembles for HtmlUnitDriver 2.40.0:
${JAVA_HOME}/jre/bin/java -cp ${M2_ROOT}/repository/org/seleniumhq/selenium/selenium-support/3.141.59/selenium-support-3.141.59.jar:${M2_ROOT}/repository/org/seleniumhq/selenium/htmlunit-driver/2.40.0/htmlunit-driver-2.40.0.jar:${M2_ROOT}/repository/org/apache/commons/commons-lang3/3.8.1/commons-lang3-3.8.1.jar:${M2_ROOT}/repository/xerces/xercesImpl/2.12.0/xercesImpl-2.12.0.jar:${M2_ROOT}/repository/org/seleniumhq/selenium/selenium-api/3.141.59/selenium-api-3.141.59.jar:${M2_ROOT}/repository/net/sourceforge/htmlunit/htmlunit-core-js/2.40.0/htmlunit-core-js-2.40.0.jar:${M2_ROOT}/repository/org/eclipse/jetty/websocket/websocket-api/9.4.28.v20200408/websocket-api-9.4.28.v20200408.jar:${M2_ROOT}/repository/xalan/xalan/2.7.2/xalan-2.7.2.jar:${M2_ROOT}/repository/org/eclipse/jetty/jetty-xml/9.4.28.v20200408/jetty-xml-9.4.28.v20200408.jar:${M2_ROOT}/repository/org/apache/httpcomponents/httpclient/4.5.12/httpclient-4.5.12.jar:${M2_ROOT}/repository/org/eclipse/jetty/jetty-http/9.4.28.v20200408/jetty-http-9.4.28.v20200408.jar:/Applications/Eclipse.app/Contents/Eclipse/plugins/com.beust.jcommander_1.72.0.jar:${M2_ROOT}/repository/org/apache/httpcomponents/httpcore/4.4.13/httpcore-4.4.13.jar:${M2_ROOT}/repository/xml-apis/xml-apis/1.4.01/xml-apis-1.4.01.jar:${M2_ROOT}/repository/commons-codec/commons-codec/1.11/commons-codec-1.11.jar:${M2_ROOT}/repository/net/sourceforge/htmlunit/neko-htmlunit/2.40.0/neko-htmlunit-2.40.0.jar:${M2_ROOT}/repository/com/squareup/okhttp3/okhttp/3.11.0/okhttp-3.11.0.jar:${M2_ROOT}/repository/commons-net/commons-net/3.6/commons-net-3.6.jar:${M2_ROOT}/repository/org/seleniumhq/selenium/selenium-server/3.141.59/selenium-server-3.141.59.jar:${M2_ROOT}/repository/xalan/serializer/2.7.2/serializer-2.7.2.jar:${M2_ROOT}/repository/org/eclipse/jetty/jetty-client/9.4.28.v20200408/jetty-client-9.4.28.v20200408.jar:${M2_ROOT}/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar:${M2_ROOT}/repository/org/apache/commons/commons-text/1.8/commons-text-1.8.jar:${M2_ROOT}/repository/org/eclipse/jetty/jetty-io/9.4.28.v20200408/jetty-io-9.4.28.v20200408.jar:${M2_ROOT}/repository/net/sourceforge/htmlunit/htmlunit-cssparser/1.5.0/htmlunit-cssparser-1.5.0.jar:${M2_ROOT}/repository/commons-logging/commons-logging/1.2/commons-logging-1.2.jar:${M2_ROOT}/repository/org/apache/httpcomponents/httpmime/4.5.12/httpmime-4.5.12.jar:${M2_ROOT}/repository/org/seleniumhq/selenium/jetty-repacked/9.4.12.v20180830/jetty-repacked-9.4.12.v20180830.jar:${M2_ROOT}/repository/javax/servlet/javax.servlet-api/3.1.0/javax.servlet-api-3.1.0.jar:${M2_ROOT}/repository/org/eclipse/jetty/websocket/websocket-client/9.4.28.v20200408/websocket-client-9.4.28.v20200408.jar:${M2_ROOT}/repository/org/brotli/dec/0.1.2/dec-0.1.2.jar:${M2_ROOT}/repository/com/google/guava/guava/28.1-jre/guava-28.1-jre.jar:${M2_ROOT}/repository/com/squareup/okio/okio/1.14.0/okio-1.14.0.jar:${M2_ROOT}/repository/net/sourceforge/htmlunit/htmlunit/2.40.0/htmlunit-2.40.0.jar:${M2_ROOT}/repository/org/seleniumhq/selenium/selenium-remote-driver/3.141.59/selenium-remote-driver-3.141.59.jar:${M2_ROOT}/repository/commons-io/commons-io/2.6/commons-io-2.6.jar:${M2_ROOT}/repository/org/eclipse/jetty/jetty-util/9.4.28.v20200408/jetty-util-9.4.28.v20200408.jar:${M2_ROOT}/repository/org/eclipse/jetty/websocket/websocket-common/9.4.28.v20200408/websocket-common-9.4.28.v20200408.jar org.openqa.grid.selenium.GridLauncherV3 -role node -servlets org.openqa.grid.web.servlet.LifecycleServlet -host 192.168.1.6 -port 34464 -nodeConfig /Users/bb8d/github/Selenium-Foundation/target-s3/classes/nodeConfig-s3-9CF40153.json
You could create your own standalone package to bundle up the dependencies if that suits your fancy. The node server is provided by the GridLauncherV3 class. I also add the LifecycleServlet plugin to enable remote shutdown. The host specification corresponds to the local machine, and the port is auto-selected from whatever is currently available.
The JSON configuration file looks like this:
{
"capabilities": [
{
"browserName": "htmlunit",
"javascriptEnabled": true,
"maxInstances": 5,
"seleniumProtocol": "WebDriver"
}
],
"custom": {
},
"debug": false,
"downPollingLimit": 2,
"enablePlatformVerification": true,
"host": "0.0.0.0",
"hub": "http:\u002f\u002f192.168.1.6:4445\u002fwd\u002fhub",
"maxSession": 5,
"nodePolling": 5000,
"nodeStatusCheckTimeout": 5000,
"port": -1,
"proxy": "org.openqa.grid.selenium.proxy.DefaultRemoteProxy",
"register": true,
"registerCycle": 5000,
"role": "node",
"servlets": [
],
"unregisterIfStillDownAfter": 60000,
"withoutServlets": [
]
}
The critical settings can be specified in the command line, but I think the config file is more manageable.