ceph/src/pybind/mgr/mds_autoscaler/module.py

   1 """
   2 Automatically scale MDSs based on status of the file-system using the FSMap
   3 """
   4
   5 import logging
   6 from typing import Any, Optional
   7 from mgr_module import MgrModule, NotifyType
   8 from ceph.deployment.service_spec import ServiceSpec
   9 import orchestrator
  10 import copy
  11
  12 log = logging.getLogger(__name__)
  13
  14
  15 class MDSAutoscaler(orchestrator.OrchestratorClientMixin, MgrModule):
  16     """
  17     MDS autoscaler.
  18     """
  19     NOTIFY_TYPES = [NotifyType.fs_map]
  20
  21     def __init__(self, *args: Any, **kwargs: Any) -> None:
  22         MgrModule.__init__(self, *args, **kwargs)
  23         self.set_mgr(self)
  24
  25     def get_service(self, fs_name: str) -> Optional[orchestrator.ServiceDescription]:
  26         service = f"mds.{fs_name}"
  27         completion = self.describe_service(service_type='mds',
  28                                            service_name=service,
  29                                            refresh=True)
  30         orchestrator.raise_if_exception(completion)
  31         if completion.result:
  32             return completion.result[0]
  33         return None
  34
  35     def update_daemon_count(self, spec: ServiceSpec, fs_name: str, abscount: int) -> ServiceSpec:
  36         ps = copy.deepcopy(spec.placement)
  37         ps.count = abscount
  38         newspec = ServiceSpec(service_type=spec.service_type,
  39                               service_id=spec.service_id,
  40                               placement=ps)
  41         return newspec
  42
  43     def get_required_standby_count(self, fs_map: dict, fs_name: str) -> int:
  44         assert fs_map is not None
  45         for fs in fs_map['filesystems']:
  46             if fs['mdsmap']['fs_name'] == fs_name:
  47                 return fs['mdsmap']['standby_count_wanted']
  48         assert False
  49
  50     def get_required_max_mds(self, fs_map: dict, fs_name: str) -> int:
  51         assert fs_map is not None
  52         for fs in fs_map['filesystems']:
  53             if fs['mdsmap']['fs_name'] == fs_name:
  54                 return fs['mdsmap']['max_mds']
  55         assert False
  56
  57     def verify_and_manage_mds_instance(self, fs_map: dict, fs_name: str) -> None:
  58         assert fs_map is not None
  59
  60         try:
  61             svc = self.get_service(fs_name)
  62             if not svc:
  63                 self.log.info(f"fs {fs_name}: no service defined; skipping")
  64                 return
  65             if not svc.spec.placement.count:
  66                 self.log.info(f"fs {fs_name}: service does not specify a count; skipping")
  67                 return
  68
  69             standbys_required = self.get_required_standby_count(fs_map, fs_name)
  70             max_mds = self.get_required_max_mds(fs_map, fs_name)
  71             want = max_mds + standbys_required
  72
  73             self.log.info(f"fs {fs_name}: "
  74                           f"max_mds={max_mds} "
  75                           f"standbys_required={standbys_required}, "
  76                           f"count={svc.spec.placement.count}")
  77
  78             if want == svc.spec.placement.count:
  79                 return
  80
  81             self.log.info(f"fs {fs_name}: adjusting daemon count from {svc.spec.placement.count} to {want}")
  82             newspec = self.update_daemon_count(svc.spec, fs_name, want)
  83             completion = self.apply_mds(newspec)
  84             orchestrator.raise_if_exception(completion)
  85         except orchestrator.OrchestratorError as e:
  86             self.log.exception(f"fs {fs_name}: exception while updating service: {e}")
  87             pass
  88
  89     def notify(self, notify_type: NotifyType, notify_id: str) -> None:
  90         if notify_type != NotifyType.fs_map:
  91             return
  92         fs_map = self.get('fs_map')
  93         if not fs_map:
  94             return
  95
  96         # we don't know for which fs config has been changed
  97         for fs in fs_map['filesystems']:
  98             fs_name = fs['mdsmap']['fs_name']
  99             self.verify_and_manage_mds_instance(fs_map, fs_name)