patch.py

# Copyright 2021-2022 NetCracker Technology Corporation
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import enum
from abc import ABC, abstractmethod
from functools import total_ordering

from kubemarine.core.action import Action


@total_ordering
class _Priority(enum.Enum):
    INVENTORY_ONLY = 0
    """
    The patch may change the inventory.
    The patch can run only LIGHT enrichment, and connect to nodes for read-only aims.
    """

    SOFTWARE_UPGRADE = 1
    "This is a service patch that should be instantiated only automatically by migrate_kubemarine.py"

    REGULAR = 2
    """
    The patch can access and make some operations on the cluster.
    Changes in the inventory are possible, but they should not affect the software upgrade procedure.
    """

    def __lt__(self, other: '_Priority') -> bool:
        return self.value < other.value


class Patch(ABC):
    def __init__(self, identifier: str):
        self.identifier = identifier

    @abstractmethod
    def priority(self) -> _Priority:
        pass

    @property
    @abstractmethod
    def action(self) -> Action:
        pass

    @property
    @abstractmethod
    def description(self) -> str:
        pass


class InventoryOnlyPatch(Patch, ABC):
    """
    The patch may change the inventory.
    Calling DynamicResources.cluster(EnrichmentStage.LIGHT) is allowed to connect to nodes for read-only aims.

    Patches if this type are executed first.
    """

    def priority(self) -> _Priority:
        return _Priority.INVENTORY_ONLY


class _SoftwareUpgradePatch(Patch, ABC):
    """This is a service patch that should be extended only by predefined set of classes inside migrate_kubemarine.py"""

    def priority(self) -> _Priority:
        return _Priority.SOFTWARE_UPGRADE


class RegularPatch(Patch, ABC):
    """
    The patch can access and make some operations on the cluster.

    Changes in the inventory are possible,
    but the cluster should be `DynamicResources.reset_cluster()` for the changes to take effect.
    The changes in the inventory should also not affect the software upgrade procedure.

    Patches if this type are executed last.
    """

    def priority(self) -> _Priority:
        return _Priority.REGULAR