Understanding the "Launch agent by connecting it to the master" Option in Jenkins

In the DevOps pipeline tutorial, when adding an Agent node we used the “java web start” method to start the agent and connect to the Jenkins server.

Many users now cannot find this option; it has been renamed in newer versions to “Launch agent by connecting it to the master”.

This option allows the agent to connect to the Jenkins server using Java Web Start; the JNLP file must be opened on the agent machine, establishing a TCP connection from the agent to the server, so the server does not need to reach the agent.

If global security is enabled, the listening port for inbound agent connections can be customized on the Jenkins server; typically the agent opens a random outbound port to the configured master port, so network permissions must allow the server’s listening port.

By default the agent starts with a GUI, but it can also run head‑less, e.g., as a Windows service or via nohup on Linux. Other launch methods may use JNLP without Java Web Start or avoid JNLP altogether.