Tal Levy 901aafb946
add APIs to Maintenance Mode in ILM (#31410)
- POST _xpack/index_lifecycle/_stop
   - issues a request to be placed into STOPPED mode (maintenance mode).
     This is not immediate, since we must first verify that
     it is safe to go from STOPPING -> STOPPED.
- POST _xpack/index_lifecycle/_start
   - issues a request to be placed back into RUNNING mode (immediately)
- GET _xpack/index_lifecycle/_status
   - get back the current mode our lifecycle management is in

- update task was hardened to support uninstalled metadata
- if no metadata is installed, the start/stop actions will install metadata
  and proceed to try and change it (default start mode is RUNNING)
- rename MAINTENANCE -> STOPPED, MAINTENANCE_REQUESTED -> STOPPING, NORMAL -> RUNNING

follow-up to #31164.
2018-06-21 09:56:02 -07:00
..