n2vc/juju_watcher.py

   1 # Copyright 2020 Canonical Ltd.
   2 #
   3 # Licensed under the Apache License, Version 2.0 (the "License");
   4 # you may not use this file except in compliance with the License.
   5 # You may obtain a copy of the License at
   6 #
   7 #     http://www.apache.org/licenses/LICENSE-2.0
   8 #
   9 #     Unless required by applicable law or agreed to in writing, software
  10 #     distributed under the License is distributed on an "AS IS" BASIS,
  11 #     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 #     See the License for the specific language governing permissions and
  13 #     limitations under the License.
  14
  15 import asyncio
  16 import time
  17 from juju.client import client
  18 from n2vc.exceptions import EntityInvalidException
  19 from n2vc.n2vc_conn import N2VCConnector
  20 from juju.model import ModelEntity, Model
  21 from juju.client.overrides import Delta
  22 from juju.status import derive_status
  23 from juju.application import Application
  24 from websockets.exceptions import ConnectionClosed
  25 import logging
  26
  27 logger = logging.getLogger("__main__")
  28
  29
  30 def status(application: Application) -> str:
  31     unit_status = []
  32     for unit in application.units:
  33         unit_status.append(unit.workload_status)
  34     return derive_status(unit_status)
  35
  36
  37 def entity_ready(entity: ModelEntity) -> bool:
  38     """
  39     Check if the entity is ready
  40
  41     :param: entity: Model entity. It can be a machine, action, or application.
  42
  43     :returns: boolean saying if the entity is ready or not
  44     """
  45     entity_type = entity.entity_type
  46     if entity_type == "machine":
  47         return entity.agent_status in ["started"]
  48     elif entity_type == "action":
  49         return entity.status in ["completed", "failed", "cancelled"]
  50     elif entity_type == "application":
  51         # Workaround for bug: https://github.com/juju/python-libjuju/issues/441
  52         return entity.status in ["active", "blocked"]
  53     else:
  54         raise EntityInvalidException("Unknown entity type: {}".format(entity_type))
  55
  56
  57 def application_ready(application: Application) -> bool:
  58     """
  59     Check if an application has a leader
  60
  61     :param: application: Application entity.
  62
  63     :returns: boolean saying if the application has a unit that is a leader.
  64     """
  65     ready_status_list = ["active", "blocked"]
  66     application_ready = application.status in ready_status_list
  67     units_ready = all(
  68         unit.workload_status in ready_status_list for unit in application.units
  69     )
  70     return application_ready and units_ready
  71
  72
  73 class JujuModelWatcher:
  74     @staticmethod
  75     async def wait_for_model(model: Model, timeout: float = 3600):
  76         """
  77         Wait for all entities in model to reach its final state.
  78
  79         :param: model:              Model to observe
  80         :param: timeout:            Timeout for the model applications to be active
  81
  82         :raises: asyncio.TimeoutError when timeout reaches
  83         """
  84
  85         if timeout is None:
  86             timeout = 3600.0
  87
  88         # Coroutine to wait until the entity reaches the final state
  89         async def wait_until_model_ready():
  90             wait_for_entity = asyncio.ensure_future(
  91                 asyncio.wait_for(
  92                     model.block_until(
  93                         lambda: all(
  94                             application_ready(application)
  95                             for application in model.applications.values()
  96                         ),
  97                     ),
  98                     timeout=timeout,
  99                 )
 100             )
 101
 102             tasks = [wait_for_entity]
 103             try:
 104                 await asyncio.wait(tasks, return_when=asyncio.FIRST_COMPLETED)
 105             finally:
 106                 # Cancel tasks
 107                 for task in tasks:
 108                     task.cancel()
 109
 110         await wait_until_model_ready()
 111         # Check model is still ready after 10 seconds
 112
 113         await asyncio.sleep(10)
 114         await wait_until_model_ready()
 115
 116     @staticmethod
 117     async def wait_for(
 118         model: Model,
 119         entity: ModelEntity,
 120         progress_timeout: float = 3600,
 121         total_timeout: float = 3600,
 122         db_dict: dict = None,
 123         n2vc: N2VCConnector = None,
 124     ):
 125         """
 126         Wait for entity to reach its final state.
 127
 128         :param: model:              Model to observe
 129         :param: entity:             Entity object
 130         :param: progress_timeout:   Maximum time between two updates in the model
 131         :param: total_timeout:      Timeout for the entity to be active
 132         :param: db_dict:            Dictionary with data of the DB to write the updates
 133         :param: n2vc:               N2VC Connector objector
 134
 135         :raises: asyncio.TimeoutError when timeout reaches
 136         """
 137
 138         if progress_timeout is None:
 139             progress_timeout = 3600.0
 140         if total_timeout is None:
 141             total_timeout = 3600.0
 142
 143         entity_type = entity.entity_type
 144         if entity_type not in ["application", "action", "machine"]:
 145             raise EntityInvalidException("Unknown entity type: {}".format(entity_type))
 146
 147         # Coroutine to wait until the entity reaches the final state
 148         wait_for_entity = asyncio.ensure_future(
 149             asyncio.wait_for(
 150                 model.block_until(lambda: entity_ready(entity)),
 151                 timeout=total_timeout,
 152             )
 153         )
 154
 155         # Coroutine to watch the model for changes (and write them to DB)
 156         watcher = asyncio.ensure_future(
 157             JujuModelWatcher.model_watcher(
 158                 model,
 159                 entity_id=entity.entity_id,
 160                 entity_type=entity_type,
 161                 timeout=progress_timeout,
 162                 db_dict=db_dict,
 163                 n2vc=n2vc,
 164             )
 165         )
 166
 167         tasks = [wait_for_entity, watcher]
 168         try:
 169             # Execute tasks, and stop when the first is finished
 170             # The watcher task won't never finish (unless it timeouts)
 171             await asyncio.wait(tasks, return_when=asyncio.FIRST_COMPLETED)
 172         finally:
 173             # Cancel tasks
 174             for task in tasks:
 175                 task.cancel()
 176
 177     @staticmethod
 178     async def model_watcher(
 179         model: Model,
 180         entity_id: str,
 181         entity_type: str,
 182         timeout: float,
 183         db_dict: dict = None,
 184         n2vc: N2VCConnector = None,
 185     ):
 186         """
 187         Observes the changes related to an specific entity in a model
 188
 189         :param: model:          Model to observe
 190         :param: entity_id:      ID of the entity to be observed
 191         :param: entity_type:    Entity Type (p.e. "application", "machine, and "action")
 192         :param: timeout:        Maximum time between two updates in the model
 193         :param: db_dict:        Dictionary with data of the DB to write the updates
 194         :param: n2vc:           N2VC Connector objector
 195
 196         :raises: asyncio.TimeoutError when timeout reaches
 197         """
 198
 199         allwatcher = client.AllWatcherFacade.from_connection(model.connection())
 200
 201         # Genenerate array with entity types to listen
 202         entity_types = (
 203             [entity_type, "unit"]
 204             if entity_type == "application"  # TODO: Add "action" too
 205             else [entity_type]
 206         )
 207
 208         # Get time when it should timeout
 209         timeout_end = time.time() + timeout
 210
 211         try:
 212             while True:
 213                 change = await allwatcher.Next()
 214                 for delta in change.deltas:
 215                     write = False
 216                     delta_entity = None
 217
 218                     # Get delta EntityType
 219                     delta_entity = delta.entity
 220
 221                     if delta_entity in entity_types:
 222                         # Get entity id
 223                         if entity_type == "application":
 224                             id = (
 225                                 delta.data["application"]
 226                                 if delta_entity == "unit"
 227                                 else delta.data["name"]
 228                             )
 229                         else:
 230                             id = delta.data["id"]
 231
 232                         # Write if the entity id match
 233                         write = True if id == entity_id else False
 234
 235                         # Update timeout
 236                         timeout_end = time.time() + timeout
 237                         (
 238                             status,
 239                             status_message,
 240                             vca_status,
 241                         ) = JujuModelWatcher.get_status(delta)
 242
 243                         if write and n2vc is not None and db_dict:
 244                             # Write status to DB
 245                             status = n2vc.osm_status(delta_entity, status)
 246                             await n2vc.write_app_status_to_db(
 247                                 db_dict=db_dict,
 248                                 status=status,
 249                                 detailed_status=status_message,
 250                                 vca_status=vca_status,
 251                                 entity_type=delta_entity,
 252                             )
 253                 # Check if timeout
 254                 if time.time() > timeout_end:
 255                     raise asyncio.TimeoutError()
 256         except ConnectionClosed:
 257             pass
 258             # This is expected to happen when the
 259             # entity reaches its final state, because
 260             # the model connection is closed afterwards
 261
 262     @staticmethod
 263     def get_status(delta: Delta) -> (str, str, str):
 264         """
 265         Get status from delta
 266
 267         :param: delta:          Delta generated by the allwatcher
 268         :param: entity_type:    Entity Type (p.e. "application", "machine, and "action")
 269
 270         :return (status, message, vca_status)
 271         """
 272         if delta.entity == "machine":
 273             return (
 274                 delta.data["agent-status"]["current"],
 275                 delta.data["instance-status"]["message"],
 276                 delta.data["instance-status"]["current"],
 277             )
 278         elif delta.entity == "action":
 279             return (
 280                 delta.data["status"],
 281                 delta.data["status"],
 282                 delta.data["status"],
 283             )
 284         elif delta.entity == "application":
 285             return (
 286                 delta.data["status"]["current"],
 287                 delta.data["status"]["message"],
 288                 delta.data["status"]["current"],
 289             )
 290         elif delta.entity == "unit":
 291             return (
 292                 delta.data["workload-status"]["current"],
 293                 delta.data["workload-status"]["message"],
 294                 delta.data["workload-status"]["current"],
 295             )