Regulate when plugin should add new EC2 Instances described in EC2 Spot Fleet into Jenkins as slave.

When unchecked.

Default behavior. Old versions of plugin use this approach.

Plugin will immediately add new EC2 Instances described in EC2 Spot Fleet into Jenkins slaves. Plugin will not check state of EC2 Instance

It takes some time to EC2 Instance to run and be able accept connections, as result Jenkins will move just added slaves to offline and will try to reconnect later. At the same time Jenkins will request more capacity from EC2 Fleet Plugin. This could over-provision your EC2 Spot Fleet, but guarantee that if new EC2 Instance has some problem to start, Jenkins will not be stuck and request move capacity, new instances.

When checked

This option is experimental, if you have questions/problems, please report GitHub Issue

Plugin will add new EC2 Spot Instances to Jenkins slaves only when EC2 Instance will be in running state.

As result Jenkins will not request over-provision capacity. Make sure that you have enabled health check for EC2 Spot Fleet to avoid case when EC2 Instance cannot be running but Jenkins wait it and doesn't request additional capacity.