Refactoring POL Charm to use Operator Framework
This refactoring work includes tests.
Note 1: old charm is in pol-k8s folder.
Note 2: relation-departed is currently not tested because there is
no function to remove a relation in the Testing Harness.
There is currently one issue open and the Charmcraft team
should provide feedback soon.
Change-Id: Ib21779c5fc781cbb5901351ccf02ca5f9b36b181
Signed-off-by: sousaedu <eduardo.sousa@canonical.com>
diff --git a/installers/charm/pol/src/charm.py b/installers/charm/pol/src/charm.py
new file mode 100755
index 0000000..649e15b
--- /dev/null
+++ b/installers/charm/pol/src/charm.py
@@ -0,0 +1,231 @@
+#!/usr/bin/env python3
+# Copyright 2020 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 pydantic import ValidationError
+from typing import Any, Dict, NoReturn
+
+from ops.charm import CharmBase, CharmEvents
+from ops.framework import EventBase, EventSource, StoredState
+from ops.main import main
+from ops.model import ActiveStatus, BlockedStatus, MaintenanceStatus
+from oci_image import OCIImageResource, OCIImageResourceError
+
+from pod_spec import make_pod_spec
+
+logger = logging.getLogger(__name__)
+
+
+class ConfigurePodEvent(EventBase):
+ """Configure Pod event"""
+
+ pass
+
+
+class PolEvents(CharmEvents):
+ """POL Events"""
+
+ configure_pod = EventSource(ConfigurePodEvent)
+
+
+class PolCharm(CharmBase):
+ """POL Charm."""
+
+ state = StoredState()
+ on = PolEvents()
+
+ def __init__(self, *args) -> NoReturn:
+ """POL Charm constructor."""
+ super().__init__(*args)
+
+ # Internal state initialization
+ self.state.set_default(pod_spec=None)
+
+ # Message bus data initialization
+ self.state.set_default(message_host=None)
+ self.state.set_default(message_port=None)
+
+ # Database data initialization
+ self.state.set_default(database_uri=None)
+
+ 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)
+ self.framework.observe(self.on.upgrade_charm, self.configure_pod)
+
+ # Registering custom internal events
+ self.framework.observe(self.on.configure_pod, self.configure_pod)
+
+ # Registering required relation events
+ self.framework.observe(
+ self.on.kafka_relation_changed, self._on_kafka_relation_changed
+ )
+ self.framework.observe(
+ self.on.mongodb_relation_changed, self._on_mongodb_relation_changed
+ )
+
+ # Registering required relation departed events
+ self.framework.observe(
+ self.on.kafka_relation_departed, self._on_kafka_relation_departed
+ )
+ self.framework.observe(
+ self.on.mongodb_relation_departed, self._on_mongodb_relation_departed
+ )
+
+ def _on_kafka_relation_changed(self, event: EventBase) -> NoReturn:
+ """Reads information about the kafka relation.
+
+ Args:
+ event (EventBase): Kafka relation event.
+ """
+ data_loc = event.unit if event.unit else event.app
+
+ message_host = event.relation.data[data_loc].get("host")
+ message_port = event.relation.data[data_loc].get("port")
+
+ if (
+ message_host
+ and message_port
+ and (
+ self.state.message_host != message_host
+ or self.state.message_port != message_port
+ )
+ ):
+ self.state.message_host = message_host
+ self.state.message_port = message_port
+ self.on.configure_pod.emit()
+
+ def _on_kafka_relation_departed(self, event: EventBase) -> NoReturn:
+ """Clear kafka relation data.
+
+ Args:
+ event (EventBase): Kafka relation event.
+ """
+ self.state.message_host = None
+ self.state.message_port = None
+ self.on.configure_pod.emit()
+
+ def _on_mongodb_relation_changed(self, event: EventBase) -> NoReturn:
+ """Reads information about the DB relation.
+
+ Args:
+ event (EventBase): DB relation event.
+ """
+ data_loc = event.unit if event.unit else event.app
+
+ database_uri = event.relation.data[data_loc].get("connection_string")
+
+ if database_uri and self.state.database_uri != database_uri:
+ self.state.database_uri = database_uri
+ self.on.configure_pod.emit()
+
+ def _on_mongodb_relation_departed(self, event: EventBase) -> NoReturn:
+ """Clear mongodb relation data.
+
+ Args:
+ event (EventBase): DB relation event.
+ """
+ self.state.database_uri = None
+ self.on.configure_pod.emit()
+
+ def _missing_relations(self) -> str:
+ """Checks if there missing relations.
+
+ Returns:
+ str: string with missing relations
+ """
+ data_status = {
+ "kafka": self.state.message_host,
+ "mongodb": self.state.database_uri,
+ }
+
+ missing_relations = [k for k, v in data_status.items() if not v]
+
+ return ", ".join(missing_relations)
+
+ @property
+ def relation_state(self) -> Dict[str, Any]:
+ """Collects relation state configuration for pod spec assembly.
+
+ Returns:
+ Dict[str, Any]: relation state information.
+ """
+ relation_state = {
+ "message_host": self.state.message_host,
+ "message_port": self.state.message_port,
+ "database_uri": self.state.database_uri,
+ }
+
+ return relation_state
+
+ def configure_pod(self, event: EventBase) -> NoReturn:
+ """Assemble the pod spec and apply it, if possible.
+
+ Args:
+ event (EventBase): Hook or Relation event that started the
+ function.
+ """
+ if missing := self._missing_relations():
+ self.unit.status = BlockedStatus(
+ "Waiting for {0} relation{1}".format(
+ missing, "s" if "," in missing else ""
+ )
+ )
+ return
+
+ if not self.unit.is_leader():
+ self.unit.status = ActiveStatus("ready")
+ 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,
+ self.relation_state,
+ self.model.app.name,
+ )
+ except ValidationError 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(PolCharm)
diff --git a/installers/charm/pol/src/pod_spec.py b/installers/charm/pol/src/pod_spec.py
new file mode 100644
index 0000000..2caafbd
--- /dev/null
+++ b/installers/charm/pol/src/pod_spec.py
@@ -0,0 +1,175 @@
+#!/usr/bin/env python3
+# Copyright 2020 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 pydantic import BaseModel, constr, PositiveInt
+from typing import Any, Dict, List
+
+logger = logging.getLogger(__name__)
+
+
+class ConfigData(BaseModel):
+ """Configuration data model."""
+
+ log_level: constr(regex=r"^(INFO|DEBUG)$")
+
+
+class RelationData(BaseModel):
+ """Relation data model."""
+
+ message_host: constr(min_length=1)
+ message_port: PositiveInt
+ database_uri: constr(regex=r"^(mongodb://)")
+
+
+def _make_pod_ports(port: int) -> List[Dict[str, Any]]:
+ """Generate pod ports details.
+
+ Args:
+ port (int): port to expose.
+
+ Returns:
+ List[Dict[str, Any]]: pod port details.
+ """
+ return [{"name": "pol", "containerPort": port, "protocol": "TCP"}]
+
+
+def _make_pod_envconfig(
+ config: Dict[str, Any], relation_state: Dict[str, Any]
+) -> Dict[str, Any]:
+ """Generate pod environment configuration.
+
+ Args:
+ config (Dict[str, Any]): configuration information.
+ relation_state (Dict[str, Any]): relation state information.
+
+ Returns:
+ Dict[str, Any]: pod environment configuration.
+ """
+ envconfig = {
+ # General configuration
+ "ALLOW_ANONYMOUS_LOGIN": "yes",
+ "OSMPOL_GLOBAL_LOGLEVEL": config["log_level"],
+ # Kafka configuration
+ "OSMPOL_MESSAGE_HOST": relation_state["message_host"],
+ "OSMPOL_MESSAGE_DRIVER": "kafka",
+ "OSMPOL_MESSAGE_PORT": relation_state["message_port"],
+ # Database configuration
+ "OSMPOL_DATABASE_DRIVER": "mongo",
+ "OSMPOL_DATABASE_URI": relation_state["database_uri"],
+ }
+
+ return envconfig
+
+
+def _make_startup_probe() -> Dict[str, Any]:
+ """Generate startup probe.
+
+ Returns:
+ Dict[str, Any]: startup probe.
+ """
+ return {
+ "exec": {"command": ["/usr/bin/pgrep", "python3"]},
+ "initialDelaySeconds": 60,
+ "timeoutSeconds": 5,
+ }
+
+
+def _make_readiness_probe() -> Dict[str, Any]:
+ """Generate readiness probe.
+
+ Returns:
+ Dict[str, Any]: readiness probe.
+ """
+ return {
+ "exec": {
+ "command": ["sh", "-c", "osm-pol-healthcheck || exit 1"],
+ },
+ "periodSeconds": 10,
+ "timeoutSeconds": 5,
+ "successThreshold": 1,
+ "failureThreshold": 3,
+ }
+
+
+def _make_liveness_probe() -> Dict[str, Any]:
+ """Generate liveness probe.
+
+ Returns:
+ Dict[str, Any]: liveness probe.
+ """
+ return {
+ "exec": {
+ "command": ["sh", "-c", "osm-pol-healthcheck || exit 1"],
+ },
+ "initialDelaySeconds": 45,
+ "periodSeconds": 10,
+ "timeoutSeconds": 5,
+ "successThreshold": 1,
+ "failureThreshold": 3,
+ }
+
+
+def make_pod_spec(
+ image_info: Dict[str, str],
+ config: Dict[str, Any],
+ relation_state: Dict[str, Any],
+ app_name: str = "pol",
+ port: int = 80,
+) -> Dict[str, Any]:
+ """Generate the pod spec information.
+
+ Args:
+ image_info (Dict[str, str]): Object provided by
+ OCIImageResource("image").fetch().
+ config (Dict[str, Any]): Configuration information.
+ relation_state (Dict[str, Any]): Relation state information.
+ app_name (str, optional): Application name. Defaults to "pol".
+ port (int, optional): Port for the container. Defaults to 80.
+
+ Returns:
+ Dict[str, Any]: Pod spec dictionary for the charm.
+ """
+ if not image_info:
+ return None
+
+ ConfigData(**(config))
+ RelationData(**(relation_state))
+
+ ports = _make_pod_ports(port)
+ env_config = _make_pod_envconfig(config, relation_state)
+
+ return {
+ "version": 3,
+ "containers": [
+ {
+ "name": app_name,
+ "imageDetails": image_info,
+ "imagePullPolicy": "Always",
+ "ports": ports,
+ "envConfig": env_config,
+ }
+ ],
+ "kubernetesResources": {
+ "ingressResources": [],
+ },
+ }