I have the same issue, might want to check the logs of your master Jenkins, in mine I have:
Oct 01, 2019 10:53:45 AM INFO hudson.plugins.ec2.EC2RetentionStrategy internalCheck
Idle timeout of [instance name] after 31 idle minutes, instance statusRUNNING
Oct 01, 2019 10:53:45 AM INFO hudson.plugins.ec2.EC2AbstractSlave idleTimeout
EC2 instance idle time expired: i-07625ee50b5a21bde
Oct 01, 2019 10:53:45 AM INFO hudson.plugins.ec2.EC2OndemandSlave terminate
Terminated EC2 instance (terminated): i-07625ee50b5a21bde
Oct 01, 2019 10:53:45 AM INFO hudson.plugins.ec2.EC2OndemandSlave terminate
Removed EC2 instance from jenkins master: i-07625ee50b5a21bde
So nodes are automatically disconnected after an idle timeout, I've raised a similar issue here: https://issues.jenkins-ci.org/browse/JENKINS-59579 |