--- /dev/null
+#!/usr/bin/env python3
+# Copyright 2021 Canonical Ltd.
+#
+# 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.
+#
+# For those usages not covered by the Apache License, Version 2.0 please
+# contact: legal@canonical.com
+#
+# To get in touch with the maintainers, please contact:
+# osm-charmers@lists.launchpad.net
+##
+
+import logging
+from typing import Dict, List, NoReturn
+
+from ops.charm import CharmBase
+from ops.framework import EventBase, StoredState
+from ops.main import main
+from ops.model import ActiveStatus, Application, BlockedStatus, MaintenanceStatus, Unit
+from oci_image import OCIImageResource, OCIImageResourceError
+
+from pod_spec import make_pod_spec
+
+logger = logging.getLogger(__name__)
+
+PROMETHEUS_PORT = 9090
+
+
+class RelationsMissing(Exception):
+ def __init__(self, missing_relations: List):
+ self.message = ""
+ if missing_relations and isinstance(missing_relations, list):
+ self.message += f'Waiting for {", ".join(missing_relations)} relation'
+ if "," in self.message:
+ self.message += "s"
+
+
+class RelationDefinition:
+ def __init__(self, relation_name: str, keys: List, source_type):
+ if source_type != Application and source_type != Unit:
+ raise TypeError(
+ "source_type should be ops.model.Application or ops.model.Unit"
+ )
+ self.relation_name = relation_name
+ self.keys = keys
+ self.source_type = source_type
+
+
+def check_missing_relation_data(
+ data: Dict,
+ expected_relations_data: List[RelationDefinition],
+):
+ missing_relations = []
+ for relation_data in expected_relations_data:
+ if not all(
+ f"{relation_data.relation_name}_{k}" in data for k in relation_data.keys
+ ):
+ missing_relations.append(relation_data.relation_name)
+ if missing_relations:
+ raise RelationsMissing(missing_relations)
+
+
+def get_relation_data(
+ charm: CharmBase,
+ relation_data: RelationDefinition,
+) -> Dict:
+ data = {}
+ relation = charm.model.get_relation(relation_data.relation_name)
+ if relation:
+ self_app_unit = (
+ charm.app if relation_data.source_type == Application else charm.unit
+ )
+ expected_type = relation_data.source_type
+ for app_unit in relation.data:
+ if app_unit != self_app_unit and isinstance(app_unit, expected_type):
+ if all(k in relation.data[app_unit] for k in relation_data.keys):
+ for k in relation_data.keys:
+ data[f"{relation_data.relation_name}_{k}"] = relation.data[
+ app_unit
+ ].get(k)
+ break
+ return data
+
+
+class PrometheusCharm(CharmBase):
+ """Prometheus Charm."""
+
+ state = StoredState()
+
+ def __init__(self, *args) -> NoReturn:
+ """Prometheus Charm constructor."""
+ super().__init__(*args)
+
+ # Internal state initialization
+ self.state.set_default(pod_spec=None)
+
+ self.port = PROMETHEUS_PORT
+ self.image = OCIImageResource(self, "image")
+
+ # Registering regular events
+ self.framework.observe(self.on.start, self.configure_pod)
+ self.framework.observe(self.on.config_changed, self.configure_pod)
+
+ # Registering provided relation events
+ self.framework.observe(
+ self.on.prometheus_relation_joined, self._publish_prometheus_info
+ )
+
+ def _publish_prometheus_info(self, event: EventBase) -> NoReturn:
+ """Publishes Prometheus information.
+
+ Args:
+ event (EventBase): Prometheus relation event.
+ """
+ if self.unit.is_leader():
+ rel_data = {
+ "host": self.model.app.name,
+ "port": str(PROMETHEUS_PORT),
+ }
+ for k, v in rel_data.items():
+ event.relation.data[self.app][k] = v
+
+ @property
+ def relations_requirements(self):
+ return []
+
+ def get_relation_state(self):
+ relation_state = {}
+ for relation_requirements in self.relations_requirements:
+ data = get_relation_data(self, relation_requirements)
+ relation_state = {**relation_state, **data}
+ check_missing_relation_data(relation_state, self.relations_requirements)
+ return relation_state
+
+ def configure_pod(self, _=None) -> NoReturn:
+ """Assemble the pod spec and apply it, if possible.
+
+ Args:
+ event (EventBase): Hook or Relation event that started the
+ function.
+ """
+ if not self.unit.is_leader():
+ self.unit.status = ActiveStatus("ready")
+ return
+
+ relation_state = None
+ try:
+ relation_state = self.get_relation_state()
+ except RelationsMissing as exc:
+ logger.exception("Relation missing error")
+ self.unit.status = BlockedStatus(exc.message)
+ return
+
+ self.unit.status = MaintenanceStatus("Assembling pod spec")
+
+ # Fetch image information
+ try:
+ self.unit.status = MaintenanceStatus("Fetching image information")
+ image_info = self.image.fetch()
+ except OCIImageResourceError:
+ self.unit.status = BlockedStatus("Error fetching image information")
+ return
+
+ try:
+ pod_spec = make_pod_spec(
+ image_info,
+ self.model.config,
+ relation_state,
+ self.model.app.name,
+ self.port,
+ )
+ except ValueError as exc:
+ logger.exception("Config/Relation data validation error")
+ self.unit.status = BlockedStatus(str(exc))
+ return
+
+ if self.state.pod_spec != pod_spec:
+ self.model.pod.set_spec(pod_spec)
+ self.state.pod_spec = pod_spec
+
+ self.unit.status = ActiveStatus("ready")
+
+
+if __name__ == "__main__":
+ main(PrometheusCharm)
projects / osm / devops.git / blobdiff