Are these swarm clients or normal dumb ssh clients? Swarm clients reconnect automatically after a disconnect, but you can "mark" them "offline".

Hey Marc,

I don't know what a "Swarm client" is. Can you clarify this for me?

I have created the slave as a "dump" slave. Setting it's status to offline has the same effect as disconnecting.

I am also having this issue. The master node is connecting to slave nodes via a service. After I disconnect a slave (and give a reason) it goes back online within a few minutes. This can cause builds to fail, because the slave will execute a build that it was not ready to do.

I think I found the issue.
It's actually not a bug, it's was me being dull

Jenkins has an option to disconnect a slave, which only cuts the connection to this slave. This triggers Jenkins to re-initiate the connection.
An alternative option is the "temporarily remove" a slave. This does what I had in mind. Jenkins ignores this slave and does not bring it back online.

Problem solved

This was actually not a bug.

This is still an issue, at least as of Jenkins 1.522.

I note that there are two actions you can take for a node:

1. "mark temporarily offline" which keeps the slave.jar running, but doesn’t send any new jobs to the slave
2. "disconnect" which means kill the slave.jar process (however, the slave process will be restarted in a few minutes)

There is no option to actually kill the slave process, and stop it restarting.

Also, there is confusion in the Jenkins code about what these options mean. If I "mark temporarily offline", then on the node staus page, it says "disconnected by ...", which is just mixing up two things that are supposed to be distinct.

A rethink of what the options are is needed.