We have been having an strange issue recently with our on-demand Windows nodes on AWS terminating as soon as the slave agent is brought online.

I create a job that has the tag aws, which is associated with a Windows AMI in our EC2 console.

I start the job.

Jenkins starts the EC2 instance. When it comes up, the master connects to the slave and tries to launch the slave.jar. Then the instance is immediately disconnected and terminated, and jenkins launches a new instance. This will continue repeatedly until the job is stopped.

Here's an example of the logs in jenkins:

INFO: Authenticating as asdc-jenkins
Feb 26, 2018 6:13:14 PM hudson.plugins.ec2.EC2Cloud log
INFO: Connecting to 10.248.9.120 on port 22, with timeout 10000.
Feb 26, 2018 6:13:14 PM hudson.plugins.ec2.EC2Cloud log
INFO: Connected via SSH.
Feb 26, 2018 6:13:14 PM hudson.plugins.ec2.EC2Cloud log
INFO: connect fresh as root
Feb 26, 2018 6:13:14 PM hudson.plugins.ec2.EC2Cloud log
INFO: Connecting to 10.248.9.120 on port 22, with timeout 10000.
Feb 26, 2018 6:13:14 PM hudson.plugins.ec2.EC2Cloud log
INFO: Connected via SSH.
Feb 26, 2018 6:13:15 PM hudson.plugins.ec2.EC2Cloud log
INFO: Creating tmp directory (/tmp) if it does not exist
Feb 26, 2018 6:13:15 PM hudson.plugins.ec2.EC2Cloud log
INFO: Verifying that java exists
Feb 26, 2018 6:13:15 PM hudson.plugins.ec2.EC2Cloud log
INFO: Copying slave.jar
Feb 26, 2018 6:13:16 PM hudson.plugins.ec2.EC2Cloud log
INFO: Launching slave agent (via Trilead SSH2 Connection): java -jar /tmp/slave.jar
Feb 26, 2018 6:13:16 PM hudson.plugins.ec2.EC2OndemandSlave terminate
INFO: Terminated EC2 instance (terminated): i-0e6028c6c76826300
Feb 26, 2018 6:13:16 PM hudson.plugins.ec2.EC2OndemandSlave terminate
INFO: Removed EC2 instance from jenkins master: i-0e6028c6c76826300

This is only happening on our windows nodes (connecting via cygwin). Mac and Linux nodes launch fine.

To make things more confusing, if I launch the instance in Jenkins, and then manually add the node to the master via the web interface, it works fine.

I've tried this on the latest version of the Windows 2016 AMI on Amazon, with only cygwin and java installed and still have this problem.