installers/charm/ng-ui/src/charm.py

   1 #!/usr/bin/env python3
   2 # Copyright 2020 Canonical Ltd.
   3 #
   4 # Licensed under the Apache License, Version 2.0 (the "License"); you may
   5 # not use this file except in compliance with the License. You may obtain
   6 # a copy of the License at
   7 #
   8 #         http://www.apache.org/licenses/LICENSE-2.0
   9 #
  10 # Unless required by applicable law or agreed to in writing, software
  11 # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  12 # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  13 # License for the specific language governing permissions and limitations
  14 # under the License.
  15 #
  16 # For those usages not covered by the Apache License, Version 2.0 please
  17 # contact: legal@canonical.com
  18 #
  19 # To get in touch with the maintainers, please contact:
  20 # osm-charmers@lists.launchpad.net
  21 ##
  22
  23 import logging
  24 from typing import Any, Dict, NoReturn
  25 from pydantic import ValidationError
  26
  27 from ops.charm import CharmBase, CharmEvents
  28 from ops.framework import EventBase, EventSource, StoredState
  29 from ops.main import main
  30 from ops.model import ActiveStatus, BlockedStatus, MaintenanceStatus
  31 from oci_image import OCIImageResource, OCIImageResourceError
  32
  33 from pod_spec import make_pod_spec
  34
  35 logger = logging.getLogger(__name__)
  36
  37 NGUI_PORT = 80
  38
  39
  40 class ConfigurePodEvent(EventBase):
  41     """Configure Pod event"""
  42
  43     pass
  44
  45
  46 class NgUiEvents(CharmEvents):
  47     """NGUI Events"""
  48
  49     configure_pod = EventSource(ConfigurePodEvent)
  50
  51
  52 class NgUiCharm(CharmBase):
  53     """NGUI Charm."""
  54
  55     state = StoredState()
  56     on = NgUiEvents()
  57
  58     def __init__(self, *args) -> NoReturn:
  59         """NGUI Charm constructor."""
  60         super().__init__(*args)
  61
  62         # Internal state initialization
  63         self.state.set_default(pod_spec=None)
  64
  65         # North bound interface initialization
  66         self.state.set_default(nbi_host=None)
  67         self.state.set_default(nbi_port=None)
  68
  69         self.http_port = NGUI_PORT
  70         self.image = OCIImageResource(self, "image")
  71
  72         # Registering regular events
  73         self.framework.observe(self.on.start, self.configure_pod)
  74         self.framework.observe(self.on.config_changed, self.configure_pod)
  75         # self.framework.observe(self.on.upgrade_charm, self.configure_pod)
  76
  77         # Registering custom internal events
  78         self.framework.observe(self.on.configure_pod, self.configure_pod)
  79
  80         # Registering required relation changed events
  81         self.framework.observe(
  82             self.on.nbi_relation_changed, self._on_nbi_relation_changed
  83         )
  84
  85         # Registering required relation departed events
  86         self.framework.observe(
  87             self.on.nbi_relation_departed, self._on_nbi_relation_departed
  88         )
  89
  90     def _on_nbi_relation_changed(self, event: EventBase) -> NoReturn:
  91         """Reads information about the nbi relation.
  92
  93         Args:
  94             event (EventBase): NBI relation event.
  95         """
  96         if event.unit not in event.relation.data:
  97             return
  98         relation_data = event.relation.data[event.unit]
  99         nbi_host = relation_data.get("host")
 100         nbi_port = relation_data.get("port")
 101
 102         if (
 103             nbi_host
 104             and nbi_port
 105             and (self.state.nbi_host != nbi_host or self.state.nbi_port != nbi_port)
 106         ):
 107             self.state.nbi_host = nbi_host
 108             self.state.nbi_port = nbi_port
 109             self.on.configure_pod.emit()
 110
 111     def _on_nbi_relation_departed(self, event: EventBase) -> NoReturn:
 112         """Clears data from nbi relation.
 113
 114         Args:
 115             event (EventBase): NBI relation event.
 116         """
 117         self.state.nbi_host = None
 118         self.state.nbi_port = None
 119         self.on.configure_pod.emit()
 120
 121     def _missing_relations(self) -> str:
 122         """Checks if there missing relations.
 123
 124         Returns:
 125             str: string with missing relations
 126         """
 127         data_status = {
 128             "nbi": self.state.nbi_host,
 129         }
 130
 131         missing_relations = [k for k, v in data_status.items() if not v]
 132
 133         return ", ".join(missing_relations)
 134
 135     @property
 136     def relation_state(self) -> Dict[str, Any]:
 137         """Collects relation state configuration for pod spec assembly.
 138
 139         Returns:
 140             Dict[str, Any]: relation state information.
 141         """
 142         relation_state = {
 143             "nbi_host": self.state.nbi_host,
 144             "nbi_port": self.state.nbi_port,
 145         }
 146         return relation_state
 147
 148     def configure_pod(self, event: EventBase) -> NoReturn:
 149         """Assemble the pod spec and apply it, if possible.
 150
 151         Args:
 152             event (EventBase): Hook or Relation event that started the
 153                                function.
 154         """
 155         if missing := self._missing_relations():
 156             self.unit.status = BlockedStatus(
 157                 f"Waiting for {missing} relation{'s' if ',' in missing else ''}"
 158             )
 159             return
 160
 161         if not self.unit.is_leader():
 162             self.unit.status = ActiveStatus("ready")
 163             return
 164
 165         self.unit.status = MaintenanceStatus("Assembling pod spec")
 166
 167         # Fetch image information
 168         try:
 169             self.unit.status = MaintenanceStatus("Fetching image information")
 170             image_info = self.image.fetch()
 171         except OCIImageResourceError:
 172             self.unit.status = BlockedStatus("Error fetching image information")
 173             return
 174
 175         try:
 176             pod_spec = make_pod_spec(
 177                 image_info,
 178                 self.config,
 179                 self.relation_state,
 180                 self.model.app.name,
 181             )
 182         except ValidationError as exc:
 183             logger.exception("Config/Relation data validation error")
 184             self.unit.status = BlockedStatus(str(exc))
 185             return
 186
 187         if self.state.pod_spec != pod_spec:
 188             self.model.pod.set_spec(pod_spec)
 189             self.state.pod_spec = pod_spec
 190
 191         self.unit.status = ActiveStatus("ready")
 192
 193
 194 if __name__ == "__main__":
 195     main(NgUiCharm)