[receiver/k8sobjectsreceiver] k8sobject receiver support leader election (open-telemetry#39054)

#### Description

As
open-telemetry#38426
move the k8sleaderelector from development to alpha, we can use it in
k8sobjectsreceiver.

---------

Co-authored-by: Antoine Toulme <[email protected]>
Co-authored-by: Christos Markou <[email protected]>

Author: 3 people

.chloggen/k8s0bject-leader-election.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: enhancement
+
+# 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: k8sobject receiver support leader election
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [39054]
+
+# (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: [user]

receiver/k8sobjectsreceiver/README.md

@@ -26,6 +26,7 @@ The following is example configuration
 ```yaml
   k8sobjects:
     auth_type: serviceAccount
+    k8s_leader_elector: k8s_leader_elector
     objects:
       - name: pods
         mode: pull
@@ -61,6 +62,7 @@ the K8s API server. This can be one of `none` (for no auth), `serviceAccount`
 use this config to specify the group to select. By default, it will select the first group.
 For example, `events` resource is available in both `v1` and `events.k8s.io/v1` APIGroup. In 
 this case, it will select `v1` by default.
+- `k8s_leader_elector` (default: none): if specified, will enable Leader Election by using `k8sleaderelector` extension
 
 
 The full list of settings exposed for this receiver are documented in [config.go](./config.go)

receiver/k8sobjectsreceiver/config.go

@@ -9,6 +9,7 @@ import (
 	"strings"
 	"time"
 
+	"go.opentelemetry.io/collector/component"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	apiWatch "k8s.io/apimachinery/pkg/watch"
 	"k8s.io/client-go/discovery"
@@ -61,6 +62,8 @@ type Config struct {
 	Objects   []*K8sObjectsConfig `mapstructure:"objects"`
 	ErrorMode ErrorMode           `mapstructure:"error_mode"`
 
+	K8sLeaderElector *component.ID `mapstructure:"k8s_leader_elector"`
+
 	// For mocking purposes only.
 	makeDiscoveryClient func() (discovery.ServerResourcesInterface, error)
 	makeDynamicClient   func() (dynamic.Interface, error)

receiver/k8sobjectsreceiver/go.mod

@@ -4,6 +4,7 @@ go 1.23.0
 
 require (
 	github.com/google/uuid v1.6.0
+	github.com/open-telemetry/opentelemetry-collector-contrib/extension/k8sleaderelector v0.125.0
 	github.com/open-telemetry/opentelemetry-collector-contrib/internal/k8sconfig v0.125.0
 	github.com/open-telemetry/opentelemetry-collector-contrib/pkg/golden v0.125.0
 	github.com/open-telemetry/opentelemetry-collector-contrib/pkg/pdatatest v0.125.0
@@ -95,6 +96,7 @@ require (
 	go.opentelemetry.io/collector/config/configtls v1.31.1-0.20250509190408-4ca0f1829e0a // indirect
 	go.opentelemetry.io/collector/consumer/consumererror v0.125.1-0.20250509190408-4ca0f1829e0a // indirect
 	go.opentelemetry.io/collector/consumer/xconsumer v0.125.1-0.20250509190408-4ca0f1829e0a // indirect
+	go.opentelemetry.io/collector/extension v1.31.1-0.20250509190408-4ca0f1829e0a // indirect
 	go.opentelemetry.io/collector/extension/extensionauth v1.31.1-0.20250509190408-4ca0f1829e0a // indirect
 	go.opentelemetry.io/collector/extension/extensionmiddleware v0.125.1-0.20250509190408-4ca0f1829e0a // indirect
 	go.opentelemetry.io/collector/featuregate v1.31.1-0.20250509190408-4ca0f1829e0a // indirect
@@ -136,7 +138,7 @@ require (
 	k8s.io/kube-openapi v0.0.0-20241105132330-32ad38e42d3f // indirect
 	k8s.io/utils v0.0.0-20241104100929-3ea5e8cea738 // indirect
 	sigs.k8s.io/json v0.0.0-20241010143419-9aa6b5e7a4b3 // indirect
-	sigs.k8s.io/structured-merge-diff/v4 v4.4.2 // indirect
+	sigs.k8s.io/structured-merge-diff/v4 v4.4.3 // indirect
 	sigs.k8s.io/yaml v1.4.0 // indirect
 )
 
@@ -158,3 +160,5 @@ replace github.com/open-telemetry/opentelemetry-collector-contrib/pkg/pdatatest
 replace github.com/open-telemetry/opentelemetry-collector-contrib/pkg/pdatautil => ../../pkg/pdatautil
 
 replace github.com/open-telemetry/opentelemetry-collector-contrib/pkg/golden => ../../pkg/golden
+
+replace github.com/open-telemetry/opentelemetry-collector-contrib/extension/k8sleaderelector => ../../extension/k8sleaderelector

receiver/k8sobjectsreceiver/go.sum

@@ -24,6 +24,7 @@ import (
 	"k8s.io/client-go/tools/cache"
 	"k8s.io/client-go/tools/watch"
 
+	"github.com/open-telemetry/opentelemetry-collector-contrib/extension/k8sleaderelector"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/k8sobjectsreceiver/internal/metadata"
 )
 
@@ -75,7 +76,7 @@ func newReceiver(params receiver.Settings, config *Config, consumer consumer.Log
 	}, nil
 }
 
-func (kr *k8sobjectsreceiver) Start(ctx context.Context, _ component.Host) error {
+func (kr *k8sobjectsreceiver) Start(ctx context.Context, host component.Host) error {
 	client, err := kr.config.getDynamicClient()
 	if err != nil {
 		return err
@@ -96,7 +97,7 @@ func (kr *k8sobjectsreceiver) Start(ctx context.Context, _ component.Host) error
 			for k := range validObjects {
 				availableResource = append(availableResource, k)
 			}
-			err := fmt.Errorf("resource not found: %s. Available resources in cluster: %v", object.Name, availableResource)
+			err = fmt.Errorf("resource not found: %s. Available resources in cluster: %v", object.Name, availableResource)
 			if handlerErr := kr.handleError(err, ""); handlerErr != nil {
 				return handlerErr
 			}
@@ -116,17 +117,46 @@ func (kr *k8sobjectsreceiver) Start(ctx context.Context, _ component.Host) error
 	}
 
 	if len(validConfigs) == 0 {
-		err := errors.New("no valid Kubernetes objects found to watch")
+		err = errors.New("no valid Kubernetes objects found to watch")
 		return err
 	}
 
-	kr.setting.Logger.Info("Object Receiver started")
-	cctx, cancel := context.WithCancel(ctx)
-	kr.cancel = cancel
+	if kr.config.K8sLeaderElector != nil {
+		k8sLeaderElector := host.GetExtensions()[*kr.config.K8sLeaderElector]
+		if k8sLeaderElector == nil {
+			return fmt.Errorf("unknown k8s leader elector %q", kr.config.K8sLeaderElector)
+		}
+
+		kr.setting.Logger.Info("registering the receiver in leader election")
+		elector, ok := k8sLeaderElector.(k8sleaderelector.LeaderElection)
+		if !ok {
+			return fmt.Errorf("the extension %T is not implement k8sleaderelector.LeaderElection", k8sLeaderElector)
+		}
 
-	for _, object := range validConfigs {
-		kr.start(cctx, object)
+		elector.SetCallBackFuncs(
+			func(ctx context.Context) {
+				cctx, cancel := context.WithCancel(ctx)
+				kr.cancel = cancel
+				for _, object := range validConfigs {
+					kr.start(cctx, object)
+				}
+				kr.setting.Logger.Info("Object Receiver started as leader")
+			},
+			func() {
+				kr.setting.Logger.Info("no longer leader, stopping")
+				err = kr.Shutdown(context.Background())
+				if err != nil {
+					kr.setting.Logger.Error("shutdown receiver error:", zap.Error(err))
+				}
+			})
+	} else {
+		cctx, cancel := context.WithCancel(ctx)
+		kr.cancel = cancel
+		for _, object := range validConfigs {
+			kr.start(cctx, object)
+		}
 	}
+
 	return nil
 }
 

receiver/k8sobjectsreceiver/receiver.go

@@ -10,11 +10,13 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/component/componenttest"
 	"go.opentelemetry.io/collector/consumer/consumertest"
 	"go.opentelemetry.io/collector/receiver/receivertest"
 	apiWatch "k8s.io/apimachinery/pkg/watch"
 
+	"github.com/open-telemetry/opentelemetry-collector-contrib/extension/k8sleaderelector/k8sleaderelectortest"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/k8sobjectsreceiver/internal/metadata"
 )
 
@@ -294,3 +296,79 @@ func TestExcludeDeletedTrue(t *testing.T) {
 
 	assert.NoError(t, r.Shutdown(ctx))
 }
+
+func TestReceiverWithLeaderElection(t *testing.T) {
+	fakeLeaderElection := &k8sleaderelectortest.FakeLeaderElection{}
+	fakeHost := &k8sleaderelectortest.FakeHost{
+		FakeLeaderElection: fakeLeaderElection,
+	}
+	leaderElectorID := component.MustNewID("k8s_leader_elector")
+
+	mockClient := newMockDynamicClient()
+	rCfg := createDefaultConfig().(*Config)
+	rCfg.makeDynamicClient = mockClient.getMockDynamicClient
+	rCfg.makeDiscoveryClient = getMockDiscoveryClient
+	rCfg.ErrorMode = PropagateError
+	rCfg.Objects = []*K8sObjectsConfig{
+		{
+			Name: "pods",
+			Mode: PullMode,
+		},
+	}
+	rCfg.K8sLeaderElector = &leaderElectorID
+
+	r, err := newReceiver(
+		receivertest.NewNopSettings(metadata.Type),
+		rCfg,
+		consumertest.NewNop(),
+	)
+	require.NoError(t, err)
+	kr := r.(*k8sobjectsreceiver)
+	sink := new(consumertest.LogsSink)
+	kr.consumer = sink
+
+	// Setup k8s resources.
+	mockClient.createPods(
+		generatePod("pod1", "default", map[string]any{
+			"environment": "production",
+		}, "1"),
+	)
+
+	err = kr.Start(context.Background(), fakeHost)
+	require.NoError(t, err)
+
+	// elected leader
+	fakeLeaderElection.InvokeOnLeading()
+
+	require.Eventually(t, func() bool {
+		// expect get 2 log records
+		return sink.LogRecordCount() == 1
+	}, 20*time.Second, 100*time.Millisecond,
+		"logs not collected")
+
+	// lost election
+	fakeLeaderElection.InvokeOnStopping()
+
+	// mock create pod again which not collected
+	mockClient.createPods(
+		generatePod("pod1", "default", map[string]any{
+			"environment": "production",
+		}, "1"),
+	)
+
+	// get back election
+	fakeLeaderElection.InvokeOnLeading()
+
+	// mock create pod finally
+	mockClient.createPods(
+		generatePod("pod1", "default", map[string]any{
+			"environment": "production",
+		}, "1"),
+	)
+
+	require.Eventually(t, func() bool {
+		// expect get 4 log records
+		return sink.LogRecordCount() == 2
+	}, 20*time.Second, 100*time.Millisecond,
+		"logs not collected")
+}