[processor/k8sattributes]: log error encountered during kube client i…

…nitialisation (open-telemetry#36385)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description

This PR adds more log output to the k8s attributes receiver to log any
errors that are encountered during the kube client initialisation, to
make troubleshooting and identifying this issue easier.

<!-- Issue number (e.g. open-telemetry#1234) or full URL to issue, if applicable. -->
#### Link to tracking issue
Fixes open-telemetry#35879

---------

Signed-off-by: Florian Bacher <[email protected]>

.chloggen/k8sattributes-k8s-client-init-log.yaml

@@ -0,0 +1,29 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: k8sattributesreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Log any errors encountered during kube client initialisation
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [35879]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: | 
+  This addresses an issue where the collector, due to an error encountered during the kubernetes client initialisation,
+  was reporting an 'unavailable' status via the health check extension without any further information to be found in the logs.
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

processor/k8sattributesprocessor/processor.go

@@ -62,6 +62,7 @@ func (kp *kubernetesprocessor) Start(_ context.Context, host component.Host) err
 
 	for _, opt := range allOptions {
 		if err := opt(kp); err != nil {
+			kp.logger.Error("Could not apply option", zap.Error(err))
 			componentstatus.ReportStatus(host, componentstatus.NewFatalErrorEvent(err))
 			return err
 		}
@@ -71,6 +72,7 @@ func (kp *kubernetesprocessor) Start(_ context.Context, host component.Host) err
 	if kp.kc == nil {
 		err := kp.initKubeClient(kp.telemetrySettings, kubeClientProvider)
 		if err != nil {
+			kp.logger.Error("Could not initialize kube client", zap.Error(err))
 			componentstatus.ReportStatus(host, componentstatus.NewFatalErrorEvent(err))
 			return err
 		}