you have to put there the DNS name or IP of the machine you want to use as Agent, it should not be the master name or IP because you already have some executors on the master configured by default thus put the master as Agent does not have any sense.
1)If you do not set the host field in the Node configuration it is possible to save it, then when it tries to connect fails with an NPE | |Host Key Verification Strategy| Known hosts for Verification Strategy| !Screenshot from 2019-04-05 13-00-24.png! Agent connection log {code} ERROR: Unexpected error in launching a agent. This is probably a bug in Jenkins. java.lang.NullPointerException at com.trilead.ssh2.KnownHosts.hostnameMatches(KnownHosts.java:313) at com.trilead.ssh2.KnownHosts.getAllKnownHostEntries(KnownHosts.java:260) at com.trilead.ssh2.KnownHosts.recommendHostkeyAlgorithms(KnownHosts.java:504) at com.trilead.ssh2.KnownHosts.getPreferredServerHostkeyAlgorithmOrder(KnownHosts.java:282) at hudson.plugins.sshslaves.verifiers.KnownHostsFileKeyVerificationStrategy.getPreferredKeyAlgorithms(KnownHostsFileKeyVerificationStrategy.java:92) at hudson.plugins.sshslaves.SSHLauncher$2.call(SSHLauncher.java:837) at hudson.plugins.sshslaves.SSHLauncher$2.call(SSHLauncher.java:833) at java.util.concurrent.FutureTask.run(FutureTask.java:266) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at java.lang.Thread.run(Thread.java:748) [04/04/19 15:40:41] Launch failed - cleaning up connection {code} 2) | |Host Key Verification Strategy| Non verifying Verification Strategy|
[SSH] Opening SSH connection to null:22.
EDIT 05-04-2019
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*Config.xml*
{code} <?xml version='1.1' encoding='UTF-8'?> <slave> <name>slave01agentNullHost</name> <description>Slave for building and packaging (the delivery)agent description</description> <remoteFS>/home/userName/jenkins_slave_nodejenkins</remoteFS> <numExecutors>1</numExecutors> <mode>NORMAL</mode> <retentionStrategy class="hudson.slaves.RetentionStrategy$Always"/> <launcher class="hudson.plugins.sshslaves.SSHLauncher" plugin="ssh-s...@1.29.4"> <port>22</port> <credentialsId>xxxxxxxxmy-xxxx-xxxx-8dd0-f9d5a90c058dcredentials</credentialsId> <launchTimeoutSeconds>210</launchTimeoutSeconds> <maxNumRetries>10</maxNumRetries> <retryWaitTime>15</retryWaitTime> <sshHostKeyVerificationStrategy class="hudson.plugins.sshslaves.verifiers.NonVerifyingKeyVerificationStrategy"/> <tcpNoDelay>true</tcpNoDelay> </launcher> <label>deliver packaging customer_releaselinux</label> <nodeProperties/> </slave> {code}
Jira is not a support site see https://wiki.jenkins.io/display/JENKINS/How+to+report+an+issue BTW, the host setting is a hostname or an IP address of a host you want to use as an agent to execute jobs in it, does not have too much complication or too much to understand.