Hello,

I've ran into an issue when launching a windows JNLP agent via the OpenStack Cloud Plugin.

The OpenStack Plugin was correctly spinning up my VM, but the slave failed to connect to my jenkins master.

To troubleshoot, I downloaded the slave.jar and launched the JNLP slave manually using this command from the slave node:

$ java -jar slave.jar -jnlpUrl http://yourserver:port/computer/slave-name/slave-agent.jnlp

I received the following error:

INFO: Trying protocol: JNLP-connect
Jan 23, 2017 12:03:59 PM hudson.remoting.jnlp.Main$CuiListener status
INFO: Protocol JNLP-connect encountered an unexpected exception
java.util.concurrent.ExecutionException: org.jenkinsci.remoting.protocol.impl.ConnectionRefusalException: Server didn't
accept the handshake:
at java.util.concurrent.FutureTask.report(Unknown Source)
at java.util.concurrent.FutureTask.get(Unknown Source)
at hudson.remoting.Engine.innerRun(Engine.java:385)
at hudson.remoting.Engine.run(Engine.java:287)
Caused by: org.jenkinsci.remoting.protocol.impl.ConnectionRefusalException: Server didn't accept the handshake:
at org.jenkinsci.remoting.engine.JnlpProtocol1Handler.sendHandshake(JnlpProtocol1Handler.java:121)
at org.jenkinsci.remoting.engine.LegacyJnlpProtocolHandler$2.call(LegacyJnlpProtocolHandler.java:162)
at org.jenkinsci.remoting.engine.LegacyJnlpProtocolHandler$2.call(LegacyJnlpProtocolHandler.java:158)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at hudson.remoting.Engine$1$1.run(Engine.java:94)
at java.lang.Thread.run(Unknown Source)

Jan 23, 2017 12:03:59 PM hudson.remoting.jnlp.Main$CuiListener error
SEVERE: The server rejected the connection: None of the protocols were accepted
java.lang.Exception: The server rejected the connection: None of the protocols were accepted
at hudson.remoting.Engine.onConnectionRejected(Engine.java:484)
at hudson.remoting.Engine.innerRun(Engine.java:448)
at hudson.remoting.Engine.run(Engine.java:287)

When investigating the logs on the Jenkins master, I noticed this:

INFO: Accepted connection #5 from /10.0.0.24:50749
Jan 21, 2017 1:18:33 AM jenkins.slaves.DefaultJnlpSlaveReceiver afterProperties
WARNING: Rejecting connection to dynamic-windows-autogen-1835 from /10.0.0.24:50749 as a JNLP agent as the launcher class jenkins.plugins.openstack.compute.JCloudsLauncher does not extend JNLPLauncher or does not implement DelegatingComputerLauncher with a delegation chain leading to a JNLPLauncher. Set system property jenkins.slaves.DefaultJnlpSlaveReceiver.disableStrictVerification=true to allowconnections until the plugin has been fixed.

Following the error message, I ran the following command from my jenkin master's groovy script console (http://master/script)

jenkins.slaves.DefaultJnlpSlaveReceiver.disableStrictVerification=true

Then I re-launched the JNLP agent using the same command and the connection was established. Likewise, after disabling strict verification, I was able to provision the node via the OpenStack Cloud plugin.

Disabling strict verification on the DefaultJnlpSlaveReceiver appears to work, is this the correct approach?

As an aside, creating a permanent node via the JNLP WebStart works and does not require disabling strict verification.

Thank you for all your hard work.

Regards,
Ryan