refactor: Replace redfish discover method. (#38)

* refactor: Replace redfish discover method.

redfish.discover_ssdp method is replaced with a simple login call to the
redfish service. If the RetriesExhaustedError exception is raised, we can
infer that the redfish service isn't present on the system.

Caching functionality of redfish discover result is maintained.

Imports redfish_client method directly instead of importing entire
redfish module.

Modifies unit tests for the new method.

Related: canonical/hardware-observer-operator#61

prometheus_hardware_exporter/collector.py

@@ -863,7 +863,7 @@ def __init__(self, config: Config) -> None:
         super().__init__(config)
         self.config = config
         self.discover_redfish_services = RedfishHelper.get_cached_discover_method(
-            self.config.redfish_discover_cache_ttl
+            self.config.redfish_discover_cache_ttl,
         )
 
     @property
@@ -946,7 +946,7 @@ def fetch(self) -> List[Payload]:
         """Load redfish data."""
         payloads: List[Payload] = []
 
-        service_status = self.discover_redfish_services()
+        service_status = self.discover_redfish_services(self.config.redfish_host)
         payloads.append(Payload(name="redfish_service_available", value=float(service_status)))
         if not service_status:
             return payloads

prometheus_hardware_exporter/collectors/redfish.py

@@ -2,10 +2,16 @@
 from logging import getLogger
 from typing import Any, Callable, Dict, List, Optional, Tuple
 
-import redfish
 import redfish_utilities
 from cachetools.func import ttl_cache
-from redfish.rest.v1 import HttpClient, RestResponse
+from redfish import redfish_client
+from redfish.rest.v1 import (
+    HttpClient,
+    InvalidCredentialsError,
+    RestResponse,
+    RetriesExhaustedError,
+    SessionCreationError,
+)
 from typing_extensions import Self
 
 from prometheus_hardware_exporter.config import Config
@@ -26,15 +32,27 @@ def get_cached_discover_method(ttl: int) -> Callable:
         """
 
         @ttl_cache(ttl=ttl)
-        def _discover() -> bool:
-            """Return true if redfish services have been discovered."""
-            logger.info("Discovering redfish services...")
-            services = redfish.discover_ssdp()
-            if len(services) == 0:
-                logger.info("No redfish services discovered")
-                return False
-            logger.debug("Discovered redfish services: %s", services)
-            return True
+        def _discover(host: str) -> bool:
+            """Return True if redfish service has been discovered."""
+            try:
+                redfish_obj = redfish_client(base_url=host, username="", password="")
+                redfish_obj.login(auth="session")
+            except RetriesExhaustedError:
+                # redfish not available
+                result = False
+            except (SessionCreationError, InvalidCredentialsError):
+                # redfish available, wrong credentials or unable to create a session
+                result = True
+            else:
+                # redfish available, login succeeded
+                result = True
+                redfish_obj.logout()
+
+            if result:
+                logger.debug("Redfish service available.")
+            else:
+                logger.debug("Redfish service not available.")
+            return result
 
         return _discover
 
@@ -49,7 +67,7 @@ def __init__(self, config: Config) -> None:
 
     def __enter__(self) -> Self:
         """Login to redfish while entering context manager."""
-        self.redfish_obj = redfish.redfish_client(
+        self.redfish_obj = redfish_client(
             base_url=self.host,
             username=self.username,
             password=self.password,

tests/unit/test_collector.py

@@ -552,7 +552,7 @@ def test_105_perccli_physical_device_command_success(self):
         ]:
             assert name in get_payloads
 
-    @patch("prometheus_hardware_exporter.collectors.redfish.redfish.redfish_client")
+    @patch("prometheus_hardware_exporter.collectors.redfish.redfish_client")
     @patch(
         "prometheus_hardware_exporter.collectors.redfish.RedfishHelper.get_cached_discover_method"
     )
@@ -578,7 +578,7 @@ def _discover(*args, **kwargs):
         mock_redfish_client.assert_not_called()
 
     @patch("prometheus_hardware_exporter.collector.logger")
-    @patch("prometheus_hardware_exporter.collectors.redfish.redfish.redfish_client")
+    @patch("prometheus_hardware_exporter.collectors.redfish.redfish_client")
     @patch(
         "prometheus_hardware_exporter.collectors.redfish.RedfishHelper.get_cached_discover_method"
     )
@@ -618,7 +618,7 @@ def _discover(*args, **kwargs):
     @patch("prometheus_hardware_exporter.collector.logger")
     @patch("prometheus_hardware_exporter.collectors.redfish.RedfishHelper.__exit__")
     @patch("prometheus_hardware_exporter.collectors.redfish.RedfishHelper.__enter__")
-    @patch("prometheus_hardware_exporter.collectors.redfish.redfish.redfish_client")
+    @patch("prometheus_hardware_exporter.collectors.redfish.redfish_client")
     @patch(
         "prometheus_hardware_exporter.collectors.redfish.RedfishHelper.get_cached_discover_method"
     )