Merge pull request #352 from Icinga:feature/summarize_performance_counter_errors

Feature: Adds support to summarize perf counter errors for all failed instances

Adds feature to `Invoke-IcingaCheckPerfCounter` to summarize an entire performance counter category, in case all instances of the check fail to prevent large outputs being written into the database

```powershell
Invoke-IcingaCheckPerfCounter -PerfCounter '\processor(*)\% processor time';

[UNKNOWN] Performance Counter [UNKNOWN] \processor(*)\% processor time
\_ [UNKNOWN] \processor(*)\% processor time
   \_ [UNKNOWN] Internal Counter Error: Failed to fetch all instances and objects for this performance counter. First error message: Example error message
```

Author: LordHepipud

doc/31-Changelog.md

@@ -18,6 +18,10 @@ Released closed milestones can be found on [GitHub](https://github.com/Icinga/ic
 
 * [#332](https://github.com/Icinga/icinga-powershell-plugins/issues/332) Adds support to provide different credentials for the `Invoke-IcingaCheckUNCPath` plugin, to run the check for a different user account
 
+### Enhancements
+
+* [#348](https://github.com/Icinga/icinga-powershell-plugins/issues/348) Adds feature to `Invoke-IcingaCheckPerfCounter` to summarize an entire performance counter category, in case all instances of the check fail to prevent large outputs being written into the database
+
 ## 1.10.1 (2022-12-20)
 
 ### Bugfixes

plugins/Invoke-IcingaCheckPerfcounter.psm1

@@ -80,11 +80,15 @@ function Invoke-IcingaCheckPerfCounter()
             $CheckPackage.AddCheck(
                 (
                     New-IcingaCheck -Name $counter -NoPerfData
-                ).SetUnknown($Counters[$counter].error, $TRUE)
-            )
+                ).SetUnknown([string]::Format('Internal Counter Error: Failed to fetch performance counter. Error message: {1}', $counter, $Counters[$counter].error), $TRUE)
+            );
             continue;
         }
 
+        # Set this to true, which means that by default we always fail
+        [bool]$CounterFailed = $TRUE;
+        [string]$FirstError  = '';
+
         foreach ($instanceName in $Counters[$counter].Keys) {
             if ((Test-IcingaArrayFilter -InputObject $instanceName -Include $IncludeCounter -Exclude $ExcludeCounter) -eq $FALSE) {
                 continue;
@@ -93,14 +97,15 @@ function Invoke-IcingaCheckPerfCounter()
             $instance = $Counters[$counter][$instanceName];
 
             if ([string]::IsNullOrEmpty($instance.error) -eq $FALSE) {
-                $CounterPackage.AddCheck(
-                    (
-                        New-IcingaCheck -Name $instanceName -NoPerfData
-                    ).SetUnknown($instance.error, $TRUE)
-                )
+                if ([string]::IsNullOrEmpty($FirstError)) {
+                    $FirstError = [string]($instance.error);
+                }
                 continue;
             }
 
+            # If we found atleast one working counter in this category, proceed
+            $CounterFailed = $FALSE;
+
             if ($instance -IsNot [hashtable]) {
                 $CounterInfo = Get-IcingaPerformanceCounterDetails -Counter $counter;
                 $IcingaCheck = New-IcingaCheck -Name $counter -Value $Counters[$counter].Value -MetricIndex $CounterInfo.Category -MetricName $CounterInfo.Counter;
@@ -114,6 +119,19 @@ function Invoke-IcingaCheckPerfCounter()
             $IcingaCheck.WarnOutOfRange($Warning).CritOutOfRange($Critical) | Out-Null;
             $CounterPackage.AddCheck($IcingaCheck);
         }
+
+        # If all of over counters failed for some reason, only print one combined error message.
+        if ($CounterFailed) {
+            if ([string]::IsNullOrEmpty($FirstError)) {
+                $FirstError = 'No counter instances could be found';
+            }
+            $CounterPackage.AddCheck(
+                (
+                    New-IcingaCheck -Name 'Internal Counter Error' -NoPerfData
+                ).SetUnknown([string]::Format('Failed to fetch all instances and objects for this performance counter. First error message: {0}', $FirstError), $TRUE)
+            );
+        }
+
         $CheckPackage.AddCheck($CounterPackage);
     }