[receiver/k8sobjects] Fix memory leak caused by pull mode's interval …

…ticker (#31919)

**Description:** <Describe what has changed.>
<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
The k8sobjects receiver was starting a ticker when in pull mode, that
would tick every set interval. This ticker needs to be stopped during
shutdown, so I added functionality to cancel the context during
shutdown, properly stopping the ticker.

The original intention here was to add `goleak`, but due to a bug in
`internal/k8stest` it's failing on the end to end test. This change
still fixes a bug, so I believe it's worth merging even without `goleak`
at this point. Note that this change does reduce the number and
frequency of goleak failures.

**Testing:** <Describe what testing was performed and which tests were
added.>
All existing tests are passing.

.chloggen/goleak_k8sobjectsreceiver.yaml

@@ -0,0 +1,27 @@
+# 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: k8sobjectsreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Fix memory leak caused by the pull mode's interval ticker
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [31919]
+
+# (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:
+
+# 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: []

receiver/k8sobjectsreceiver/receiver.go

@@ -34,6 +34,7 @@ type k8sobjectsreceiver struct {
 	consumer        consumer.Logs
 	obsrecv         *receiverhelper.ObsReport
 	mu              sync.Mutex
+	cancel          context.CancelFunc
 }
 
 func newReceiver(params receiver.CreateSettings, config *Config, consumer consumer.Logs) (receiver.Logs, error) {
@@ -72,14 +73,21 @@ func (kr *k8sobjectsreceiver) Start(ctx context.Context, _ component.Host) error
 	kr.client = client
 	kr.setting.Logger.Info("Object Receiver started")
 
+	cctx, cancel := context.WithCancel(ctx)
+	kr.cancel = cancel
+
 	for _, object := range kr.config.Objects {
-		kr.start(ctx, object)
+		kr.start(cctx, object)
 	}
 	return nil
 }
 
 func (kr *k8sobjectsreceiver) Shutdown(context.Context) error {
 	kr.setting.Logger.Info("Object Receiver stopped")
+	if kr.cancel != nil {
+		kr.cancel()
+	}
+
 	kr.mu.Lock()
 	for _, stopperChan := range kr.stopperChanList {
 		close(stopperChan)
@@ -118,7 +126,7 @@ func (kr *k8sobjectsreceiver) startPull(ctx context.Context, config *K8sObjectsC
 	kr.mu.Lock()
 	kr.stopperChanList = append(kr.stopperChanList, stopperChan)
 	kr.mu.Unlock()
-	ticker := newTicker(config.Interval)
+	ticker := newTicker(ctx, config.Interval)
 	listOption := metav1.ListOptions{
 		FieldSelector: config.FieldSelector,
 		LabelSelector: config.LabelSelector,
@@ -263,16 +271,22 @@ func getResourceVersion(ctx context.Context, config *K8sObjectsConfig, resource
 
 // Start ticking immediately.
 // Ref: https://stackoverflow.com/questions/32705582/how-to-get-time-tick-to-tick-immediately
-func newTicker(repeat time.Duration) *time.Ticker {
+func newTicker(ctx context.Context, repeat time.Duration) *time.Ticker {
 	ticker := time.NewTicker(repeat)
 	oc := ticker.C
 	nc := make(chan time.Time, 1)
 	go func() {
 		nc <- time.Now()
-		for tm := range oc {
-			nc <- tm
+		for {
+			select {
+			case tm := <-oc:
+				nc <- tm
+			case <-ctx.Done():
+				return
+			}
 		}
 	}()
+
 	ticker.C = nc
 	return ticker
 }