Enhance charm's life-cycle

config.yaml

@@ -8,7 +8,7 @@ options:
     default: 10000
     description: |
       Start the prometheus exporter at "exporter-port". By default, it will
-      start at port 10000.
+      start at port 10000. Allowed values are between 1 and 65535 inclusively.
   exporter-log-level:
     type: string
     default: "INFO"

src/charm.py

@@ -8,14 +8,14 @@
 from typing import Any, Dict, Optional
 
 import ops
-from charms.grafana_agent.v0.cos_agent import COSAgentProvider
 from ops.framework import EventBase, StoredState
-from ops.model import ActiveStatus, BlockedStatus
+from ops.model import ActiveStatus, BlockedStatus, ErrorStatus, MaintenanceStatus
 
-from config import HWTool
+import cos_agent
+import service
+from config import EXPORTER_RELATION_NAME, HWTool
 from hardware import get_bmc_address
-from hw_tools import HWToolHelper, bmc_hw_verifier
-from service import Exporter
+from hw_tools import HWToolHelper
 
 logger = logging.getLogger(__name__)
 
@@ -29,144 +29,162 @@ def __init__(self, *args: Any) -> None:
         """Init."""
         super().__init__(*args)
         self.hw_tool_helper = HWToolHelper()
-
-        self.cos_agent_provider = COSAgentProvider(
+        self.exporter = service.Exporter(self.charm_dir)
+        self.cos_agent_relation_handler = cos_agent.Handler(
             self,
+            exporter=self.exporter,
+            relation_name=EXPORTER_RELATION_NAME,
             metrics_endpoints=[
-                {"path": "/metrics", "port": int(self.model.config["exporter-port"])}
+                {
+                    "path": "/metrics",
+                    "port": int(
+                        self.model.config["exporter-port"],
+                    ),
+                }
             ],
         )
-        self.exporter = Exporter(self.charm_dir)
 
         self.framework.observe(self.on.config_changed, self._on_config_changed)
         self.framework.observe(self.on.install, self._on_install_or_upgrade)
         self.framework.observe(self.on.remove, self._on_remove)
         self.framework.observe(self.on.update_status, self._on_update_status)
         self.framework.observe(self.on.upgrade_charm, self._on_install_or_upgrade)
-        self.framework.observe(
-            self.on.cos_agent_relation_joined, self._on_cos_agent_relation_joined
-        )
-        self.framework.observe(
-            self.on.cos_agent_relation_departed, self._on_cos_agent_relation_departed
-        )
-
-        self._stored.set_default(installed=False, config={}, blocked_msg="")
-
-    def _on_install_or_upgrade(self, event: ops.InstallEvent) -> None:
-        """Install and upgrade."""
-        port = self.model.config.get("exporter-port", "10000")
-        level = self.model.config.get("exporter-log-level", "INFO")
 
-        redfish_creds = self._get_redfish_creds()
-
-        self.exporter.install(port, level, redfish_creds)
-        installed, msg = self.hw_tool_helper.install(self.model.resources)
-        self._stored.installed = installed
+        self._stored.set_default(
+            config={},
+            exporter_installed=False,
+            resource_install_result={},
+        )
 
-        if not installed:
-            logger.info(msg)
-            self._stored.blocked_msg = msg
-            self._on_update_status(event)
+    def _on_install_or_upgrade(self, _: ops.InstallEvent) -> None:
+        """Install or upgrade charm."""
+        self.model.unit.status = MaintenanceStatus("Installing resources...")
+        resource_white_list = self.hw_tool_helper.get_resource_white_list(self.model.resources)
+        resource_install_result = self.hw_tool_helper.install(
+            resource_white_list,
+            resource_black_list=self._stored.resource_install_result,  # type: ignore[arg-type]
+        )
+        self._stored.resource_install_result = resource_install_result
+        if not all(resource_install_result.values()):
+            failed_resources = [r for r, s in resource_install_result.items() if not s]
+            msg = f"Failed to install resources: {', '.join(failed_resources)}"
+            logger.error(msg)
+            self.model.unit.status = ErrorStatus(msg)
             return
 
-        self._stored.installed = True
-        self._stored.blocked_msg = ""
-        self.model.unit.status = ActiveStatus("Install complete")
-        logger.info("Install complete")
+        if self._stored.exporter_installed is not True:
+            self.model.unit.status = MaintenanceStatus("Installing exporter...")
+            success = self.cos_agent_relation_handler.install_exporter()
+            self._stored.exporter_installed = success
+            if not success:
+                msg = "Failed to install exporter, please refer to `juju debug-log`"
+                logger.error(msg)
+                self.model.unit.status = ErrorStatus(msg)
+                return
+
+        self.update_status()
 
     def _on_remove(self, _: EventBase) -> None:
         """Remove everything when charm is being removed."""
         logger.info("Start to remove.")
-        # Remove binary tool
         self.hw_tool_helper.remove(self.model.resources)
-        self.exporter.uninstall()
+        self._stored.resource_install_result = {}
+        success = self.cos_agent_relation_handler.uninstall_exporter()
+        if not success:
+            msg = "Failed to uninstall exporter, please refer to `juju debug-log`"
+            logger.warning(msg)
+        self._stored.exporter_installed = not success
         logger.info("Remove complete")
 
     def _on_update_status(self, _: EventBase) -> None:
         """Update the charm's status."""
-        if self._stored.installed is not True and self._stored.blocked_msg != "":
-            self.model.unit.status = BlockedStatus(self._stored.blocked_msg)  # type: ignore
+        self.update_status()
+
+    def _on_config_changed(self, _: EventBase) -> None:
+        """Reconfigure charm."""
+        change_set = self.update_config_store()
+
+        if self.cos_agent_relation_handler.exporter_enabled:
+            options = self.get_exporter_configs()
+            success, message = self.cos_agent_relation_handler.validate_exporter_configs(options)
+            if not success:
+                self.model.unit.status = BlockedStatus(message)
+                return
+
+            success = self.cos_agent_relation_handler.configure_exporter(options, change_set)
+            if not success:
+                message = "Failed to configure exporter, please check if the server is healthy."
+                self.model.unit.status = BlockedStatus(message)
+                return
+
+        self.update_status()
+
+    def update_status(self) -> None:
+        """Update the charm's status."""
+        if not self.cos_agent_relation_handler.exporter_enabled:
+            self.model.unit.status = BlockedStatus(f"Missing relation: [{EXPORTER_RELATION_NAME}]")
             return
-        if not self.model.get_relation("cos-agent"):
-            self.model.unit.status = BlockedStatus("Missing relation: [cos-agent]")
+
+        if self.cos_agent_relation_handler.too_many_relations:
+            self.model.unit.status = BlockedStatus("Cannot relate to more than one grafana-agent")
             return
-        if not self.exporter.check_health():
-            self.model.unit.status = BlockedStatus("Exporter is unhealthy")
+
+        if (
+            self.cos_agent_relation_handler.exporter_enabled
+            and not self.cos_agent_relation_handler.exporter_online
+        ):
+            error_msg = "Exporter crashed unexpectedly, please refer to systemd logs..."
+            self.model.unit.status = ErrorStatus(error_msg)
             return
-        if not self.exporter.check_active():
-            self.model.unit.status = BlockedStatus("Exporter is not running")
+
+        hw_tool_ok, error_msg = self.hw_tool_helper.check_status()
+        if not hw_tool_ok:
+            self.model.unit.status = ErrorStatus(error_msg)
             return
+
         self.model.unit.status = ActiveStatus("Unit is ready")
 
-    def _on_config_changed(self, event: EventBase) -> None:
-        """Reconfigure charm."""
-        # Keep track of what model config options + some extra config related
-        # information are changed. This can be helpful when we want to respond
-        # to the change of a specific config option.
+    def update_config_store(self) -> set:
+        """Update the config store, and return a set of config options that are changed."""
         change_set = set()
         model_config: Dict[str, Optional[str]] = dict(self.model.config.items())
         for key, value in model_config.items():
             if key not in self._stored.config or self._stored.config[key] != value:  # type: ignore
                 logger.info("Setting %s to: %s", key, value)
                 self._stored.config[key] = value  # type: ignore
                 change_set.add(key)
+        return change_set
+
+    def get_redfish_options(self) -> Dict[str, Any]:
+        """Get redfish config options."""
+        redfish_options = {
+            "enable": False,
+            "host": "",
+            "username": self.model.config.get("redfish-username", ""),
+            "password": self.model.config.get("redfish-password", ""),
+        }
 
-        if not self._stored.installed:  # type: ignore
-            logging.info(  # type: ignore
-                "Config changed called before install complete, deferring event: %s",
-                event.handle,
-            )
-            event.defer()
-            return
+        bmc_address = get_bmc_address()
+        if bmc_address:
+            redfish_options["enable"] = True
+            redfish_options["host"] = f"https://{bmc_address}"
 
-        exporter_configs = {
-            "exporter-port",
-            "exporter-log-level",
-            "redfish-host",
-            "redfish-username",
-            "redfish-password",
+        return redfish_options
+
+    def get_exporter_configs(self) -> Dict[str, Any]:
+        """Get the exporter related config options."""
+        port = self.model.config.get("exporter-port", "10000")
+        level = self.model.config.get("exporter-log-level", "INFO")
+        collectors = self.hw_tool_helper.hw_collector_white_list
+        redfish_options = {"enable": False}
+        if HWTool.REDFISH in collectors:
+            redfish_options = self.get_redfish_options()
+        return {
+            "port": port,
+            "level": level,
+            "collectors": collectors,
+            "redfish_options": redfish_options,
         }
-        if exporter_configs.intersection(change_set):
-            logger.info("Detected changes in exporter config.")
-            port = self.model.config.get("exporter-port", "10000")
-            level = self.model.config.get("exporter-log-level", "INFO")
-
-            redfish_creds = self._get_redfish_creds()
-            success = self.exporter.template.render_config(
-                port=port, level=level, redfish_creds=redfish_creds
-            )
-            # First condition prevent the exporter from starting at when the
-            # charm just installed; the second condition tries to recover the
-            # exporter from failed status.
-            if success and self.exporter.check_active() or not self.exporter.check_health():
-                self.exporter.restart()
-
-        self._on_update_status(event)
-
-    def _on_cos_agent_relation_joined(self, event: EventBase) -> None:
-        """Start the exporter when relation joined."""
-        self.exporter.start()
-        self._on_update_status(event)
-
-    def _on_cos_agent_relation_departed(self, event: EventBase) -> None:
-        """Remove the exporter when relation departed."""
-        self.exporter.stop()
-        self._on_update_status(event)
-
-    def _get_redfish_creds(self) -> Dict[str, str]:
-        """Provide redfish config if redfish is available, else empty dict."""
-        bmc_tools = bmc_hw_verifier()
-        if HWTool.REDFISH in bmc_tools:
-            bmc_address = get_bmc_address()
-            redfish_creds = {
-                # Force to use https as default protocol
-                "host": f"https://{bmc_address}",
-                "username": self.model.config.get("redfish-username", ""),
-                "password": self.model.config.get("redfish-password", ""),
-            }
-        else:
-            redfish_creds = {}
-        return redfish_creds
 
 
 if __name__ == "__main__":  # pragma: nocover

src/checksum.py

@@ -14,21 +14,15 @@
 #
 # For further info, check https://github.com/canonical/charmcraft
 """Checksum definition, check functions and related utils."""
-import hashlib
 import logging
 import typing as t
 from dataclasses import dataclass, field
-from pathlib import Path
 
-from os_platform import Architecture, UbuntuSeries, get_os_platform
+from os_platform import Architecture, UbuntuSeries
 
 logger = logging.getLogger(__name__)
 
 
-class ResourceChecksumError(Exception):
-    """Raise if checksum does not match."""
-
-
 @dataclass
 class ToolVersionInfo:
     """Tool version information for checksum comparison."""
@@ -209,27 +203,3 @@ class ToolVersionInfo:
         sha256_checksum="458d51b030468901fc8a207088070e6ce82db34b181d9190c8f849605f1b9b6d",
     ),
 ]
-
-
-def validate_checksum(support_version_infos: t.List[ToolVersionInfo], path: Path) -> bool:
-    """Validate checksum of resource file by checking with supported versions.
-
-    Returns True if resource is supported by the charm, architecture, and
-    checksum validation is successful.
-    """
-    os_platform = get_os_platform()
-
-    supported_checksums = []
-    for info in support_version_infos:
-        if os_platform.machine in info.supported_architectures and (
-            info.support_all_series or os_platform.series in info.supported_series
-        ):
-            supported_checksums.append(info.sha256_checksum)
-
-    with open(path, "rb") as f:
-        sha256_hash = hashlib.sha256(f.read()).hexdigest()
-
-    if sha256_hash in supported_checksums:
-        return True
-    logger.warning("Checksum validation fail, path: %s hash: %s", path, sha256_hash)
-    return False

src/config.py

@@ -9,6 +9,7 @@
 EXPORTER_SERVICE_PATH = Path(f"/etc/systemd/system/{EXPORTER_NAME}.service")
 EXPORTER_CONFIG_TEMPLATE = f"{EXPORTER_NAME}-config.yaml.j2"
 EXPORTER_SERVICE_TEMPLATE = f"{EXPORTER_NAME}.service.j2"
+EXPORTER_RELATION_NAME = "cos-agent"
 
 # Redfish
 REDFISH_TIMEOUT = 3