installers/charm/osm-temporal-ui/src/charm.py

#!/usr/bin/env python3
# Copyright 2022 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
#
#
# Learn more at: https://juju.is/docs/sdk

"""OSM Temporal charm.

See more: https://charmhub.io/osm
"""

import logging
import os
import socket

from log import log_event_handler
from typing import Any, Dict

from charms.nginx_ingress_integrator.v0.ingress import IngressRequires
from charms.observability_libs.v1.kubernetes_service_patch import KubernetesServicePatch
from charms.osm_libs.v0.utils import (
    CharmError,
    check_container_ready,
    check_service_active,
)
from charms.osm_temporal.v0.temporal import TemporalRequires
from lightkube.models.core_v1 import ServicePort
from ops.charm import CharmBase
from ops.framework import StoredState
from ops.main import main
from ops.model import ActiveStatus, Container

logger = logging.getLogger(__name__)
SERVICE_PORT = 8080


class OsmTemporalUICharm(CharmBase):
    """OSM Temporal Kubernetes sidecar charm."""

    _stored = StoredState()
    container_name = "temporal-ui"
    service_name = "temporal-ui"

    def __init__(self, *args):
        super().__init__(*args)

        self.ingress = IngressRequires(
            self,
            {
                "service-hostname": self.external_hostname,
                "service-name": self.app.name,
                "service-port": SERVICE_PORT,
            },
        )
        logger.info(f"Ingress = f{self.ingress}")
        self._observe_charm_events()
        self.container: Container = self.unit.get_container(self.container_name)
        self._stored.set_default(leader_ip="")
        self._stored.set_default(unit_ip="")
        self.temporal = TemporalRequires(self)
        self._patch_k8s_service()

    @property
    def external_hostname(self) -> str:
        """External hostname property.

        Returns:
            str: the external hostname from config.
                If not set, return the ClusterIP service name.
        """
        return self.config.get("external-hostname") or self.app.name

    # ---------------------------------------------------------------------------
    #   Handlers for Charm Events
    # ---------------------------------------------------------------------------

    @log_event_handler(logger)
    def _on_config_changed(self, event) -> None:
        """Handler for the config-changed event."""
        try:
            self._validate_config()
            self._check_relations()

            # Check if the container is ready.
            # Eventually it will become ready after the first pebble-ready event.
            check_container_ready(self.container)
            self._configure_service(self.container)
            self._update_ingress_config()
            # Update charm status
            self._on_update_status(event)
        except CharmError as e:
            logger.error(e.message)
            self.unit.status = e.status

    @log_event_handler(logger)
    def _on_update_status(self, _=None) -> None:
        """Handler for the update-status event."""
        try:
            self._validate_config()
            self._check_relations()
            check_service_active(self.container, self.service_name)
            self.unit.status = ActiveStatus()
        except CharmError as e:
            logger.error(e.message)
            self.unit.status = e.status

    @log_event_handler(logger)
    def _on_required_relation_broken(self, event) -> None:
        """Handler for the kafka-broken event."""
        # Check Pebble has started in the container
        try:
            check_container_ready(self.container)
            check_service_active(self.container, self.service_name)
            self.container.stop(self.container_name)
        except CharmError:
            pass
        self._on_update_status(event)

    # ---------------------------------------------------------------------------
    #   Validation and configuration and more
    # ---------------------------------------------------------------------------

    def _patch_k8s_service(self) -> None:
        port = ServicePort(SERVICE_PORT, name=f"{self.app.name}")
        self.service_patcher = KubernetesServicePatch(self, [port])

    def _observe_charm_events(self) -> None:
        event_handler_mapping = {
            # Core lifecycle events
            self.on.temporal_ui_pebble_ready: self._on_config_changed,
            self.on.config_changed: self._on_config_changed,
            self.on.update_status: self._on_update_status,
        }

        # Relation events
        for relation in [self.on[rel_name] for rel_name in ["temporal"]]:
            event_handler_mapping[relation.relation_changed] = self._on_config_changed
            event_handler_mapping[relation.relation_broken] = self._on_required_relation_broken

        for event, handler in event_handler_mapping.items():
            self.framework.observe(event, handler)

    def _validate_config(self) -> None:
        """Validate charm configuration.

        Raises:
            CharmError: if charm configuration is invalid.
        """
        logger.debug("validating charm config")

    def _check_relations(self) -> None:
        """Validate charm relations.

        Raises:
            CharmError: if charm configuration is invalid.
        """
        logger.debug("check for missing relations")
        missing_relations = []

        if not self.temporal.host or not self.temporal.port:
            missing_relations.append("temporal")

        if missing_relations:
            relations_str = ", ".join(missing_relations)
            one_relation_missing = len(missing_relations) == 1
            error_msg = f'need {relations_str} relation{"" if one_relation_missing else "s"}'
            logger.warning(error_msg)
            raise CharmError(error_msg)

    def _update_ingress_config(self) -> None:
        """Update ingress config in relation."""
        ingress_config = {
            "service-hostname": self.external_hostname,
        }
        if "tls-secret-name" in self.config:
            ingress_config["tls-secret-name"] = self.config["tls-secret-name"]
        logger.debug(f"updating ingress-config: {ingress_config}")
        self.ingress.update_config(ingress_config)

    def _configure_service(self, container: Container) -> None:
        """Add Pebble layer with the temporal service."""
        logger.debug(f"configuring {self.app.name} service")
        logger.info(f"{self._get_layer()}")
        container.add_layer("temporal-ui", self._get_layer(), combine=True)
        container.replan()

    def _get_layer(self) -> Dict[str, Any]:
        """Get layer for Pebble."""
        return {
            "summary": "Temporal layer",
            "description": "pebble config layer for Temporal",
            "services": {
                self.service_name: {
                    "override": "replace",
                    "summary": "temporal web ui service",
                    "command": "/home/ui-server/start-ui-server.sh",
                    "startup": "enabled",
                    "user": "temporal",
                    "group": "temporal",
                    "ports": [8080,],
                    "environment": {
                        "TEMPORAL_ADDRESS": self.temporal.host + ":" +
                            str(self.temporal.port),
                        "TEMPORAL_CORS_ORIGINS": "http://localhost:3000",
                    },
                },
            },
        }


if __name__ == "__main__":  # pragma: no cover
    main(OsmTemporalUICharm)