Currently all nodes are created with Node.Mode.EXCLUSIVE flag. It would be very useful if this can be driven by a new property attribute for each node.

There are 4 different use-cases:

• node has defined labels and EXCLUSIVE flag isn't set
  • either a job asking for any of these labels or if a job is non restricted it can be scheduled on such a node
• node has defined labels and EXCLUSIVE flag
  • only a job asking for any of these labels can be scheduled on such a node
• node hasn't defined labels and EXCLUSIVE flag isn't set
  • any job can be schedules on such a node
  • this is partially subject of JENKINS-38366
• node hasn't defined labels and EXCLUSIVE flags is set
  • doesn't make sense because Jenkins is unable to schedule a job on such a node even it asks for its provision
  • such a node should be reported with WARNING message

Possible implementation:

• a new EXCLUSIVE_MODE attribute supported on Foreman side
  • treats value 'true' as Node.Mode.EXCLUSIVE, otherwise Node.Mode.NORMAL
• if a node has an EXCLUSIVE_MODE attribute defined, use its value
  • if a node hasn't defined any label and yet has EXCLUSIVE_MODE set to 'true', report it with a warning message to the LOG
• if a node hasn't an EXCLUSIVE_MODE attribute defined treats it like
  • node has defined label(s) -> Node.Mode.EXCLUSIVE
  • node hasn't defined any label -> Node.Mode.NORMAL