[receiver/k8sobjects] Support running in kubernetes leader election mode.

.chloggen/support-kubernetes-leader-election.yaml

@@ -0,0 +1,21 @@
+# Use this changelog template to create an entry for release notes.
+# If your change doesn't affect end users, such as a test fix or a tooling change,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+
+# 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: Support running in kubernetes leader election mode.
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [17369]
+
+# (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:
+  Support running in kubernetes leader election mode.

internal/k8sconfig/go.mod

@@ -3,6 +3,7 @@ module github.com/open-telemetry/opentelemetry-collector-contrib/internal/k8scon
 go 1.19
 
 require (
+	github.com/google/uuid v1.3.0
 	github.com/openshift/client-go v0.0.0-20210521082421-73d9475a9142
 	k8s.io/apimachinery v0.27.4
 	k8s.io/client-go v0.27.4
@@ -20,7 +21,6 @@ require (
 	github.com/google/gnostic v0.5.7-v3refs // indirect
 	github.com/google/go-cmp v0.5.9 // indirect
 	github.com/google/gofuzz v1.2.0 // indirect
-	github.com/google/uuid v1.3.0 // indirect
 	github.com/imdario/mergo v0.3.11 // indirect
 	github.com/josharian/intern v1.0.0 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect

internal/k8sconfig/leaderelection.go

@@ -0,0 +1,98 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package k8sconfig // import "github.com/open-telemetry/opentelemetry-collector-contrib/internal/k8sconfig"
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"time"
+
+	"github.com/google/uuid"
+	"k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/tools/leaderelection"
+	"k8s.io/client-go/tools/leaderelection/resourcelock"
+)
+
+// LeaderElectionConfig is used to enable leader election
+type LeaderElectionConfig struct {
+	Enabled          bool   `mapstructure:"enabled"`
+	LeaderElectionID string `mapstructure:"leader_election_id"`
+}
+
+const (
+	inClusterNamespacePath  = "/var/run/secrets/kubernetes.io/serviceaccount/namespace"
+	defaultLeaderElectionID = "opentelemetry-collector"
+	defaultNamespace        = "default"
+	defaultLeaseDuration    = 15 * time.Second
+	defaultRenewDeadline    = 10 * time.Second
+	defaultRetryPeriod      = 2 * time.Second
+)
+
+// NewResourceLock creates a new config map resource lock for use in a leader election loop
+func newResourceLock(client kubernetes.Interface, leaderElectionID string) (resourcelock.Interface, error) {
+	if leaderElectionID == "" {
+		leaderElectionID = defaultLeaderElectionID
+	}
+
+	leaderElectionNamespace, err := getInClusterNamespace()
+	if err != nil {
+		leaderElectionNamespace = defaultNamespace
+	}
+
+	// Leader id, needs to be unique
+	id, err := os.Hostname()
+	if err != nil {
+		return nil, err
+	}
+	id = id + "_" + uuid.New().String()
+
+	return resourcelock.New(resourcelock.ConfigMapsLeasesResourceLock,
+		leaderElectionNamespace,
+		leaderElectionID,
+		client.CoreV1(),
+		client.CoordinationV1(),
+		resourcelock.ResourceLockConfig{
+			Identity: id,
+		})
+}
+
+func getInClusterNamespace() (string, error) {
+	// Check whether the namespace file exists.
+	// If not, we are not running in cluster so can't guess the namespace.
+	_, err := os.Stat(inClusterNamespacePath)
+	if os.IsNotExist(err) {
+		return "", fmt.Errorf("not running in-cluster, please specify leaderElectionIDspace")
+	} else if err != nil {
+		return "", fmt.Errorf("error checking namespace file: %w", err)
+	}
+
+	// Load the namespace file and return its content
+	namespace, err := os.ReadFile(inClusterNamespacePath)
+	if err != nil {
+		return "", fmt.Errorf("error reading namespace file: %w", err)
+	}
+	return string(namespace), nil
+}
+
+// NewLeaderElector return  a leader elector object using client-go
+func NewLeaderElector(leaderElectionID string, client kubernetes.Interface, startFunc func(context.Context), stopFunc func()) (*leaderelection.LeaderElector, error) {
+	resourceLock, err := newResourceLock(client, leaderElectionID)
+	if err != nil {
+		return &leaderelection.LeaderElector{}, err
+	}
+
+	// TODO: make those configurable.
+	l, err := leaderelection.NewLeaderElector(leaderelection.LeaderElectionConfig{
+		Lock:          resourceLock,
+		LeaseDuration: defaultLeaseDuration,
+		RenewDeadline: defaultRenewDeadline,
+		RetryPeriod:   defaultRetryPeriod,
+		Callbacks: leaderelection.LeaderCallbacks{
+			OnStartedLeading: startFunc,
+			OnStoppedLeading: stopFunc,
+		},
+	})
+	return l, err
+}

receiver/k8sobjectsreceiver/README.md

@@ -25,6 +25,9 @@ The following is example configuration
 
 ```yaml
   k8sobjects:
+    leader_election:
+      enabled: true
+      leader_election_id: "my-opentelemetry-collector"
     auth_type: serviceAccount
     objects:
       - name: pods
@@ -39,6 +42,9 @@ The following is example configuration
 ```
 
 Brief description of configuration properties:
+- `leader_election`: running in Kubernetes with leader election mode, this means that multiple instances are running, but only one is active at a time, and if it fails, another one is elected as leader and takes its place.
+  - `enabled` (default = `false`): whether run in leader election mode.
+  - `leader_election_id` (default = `e3385b9a.leader-election.opentelemetry-collector`): the identity name of holder. 
 - `auth_type` (default = `serviceAccount`): Determines how to authenticate to
 the K8s API server. This can be one of `none` (for no auth), `serviceAccount`
 (to use the standard service account token provided to the agent pod), or

receiver/k8sobjectsreceiver/config.go

@@ -11,6 +11,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/client-go/discovery"
 	"k8s.io/client-go/dynamic"
+	"k8s.io/client-go/kubernetes"
 
 	"github.com/open-telemetry/opentelemetry-collector-contrib/internal/k8sconfig"
 )
@@ -46,11 +47,13 @@ type K8sObjectsConfig struct {
 type Config struct {
 	k8sconfig.APIConfig `mapstructure:",squash"`
 
-	Objects []*K8sObjectsConfig `mapstructure:"objects"`
+	Objects        []*K8sObjectsConfig            `mapstructure:"objects"`
+	LeaderElection k8sconfig.LeaderElectionConfig `mapstructure:"leader_election"`
 
 	// For mocking purposes only.
 	makeDiscoveryClient func() (discovery.ServerResourcesInterface, error)
 	makeDynamicClient   func() (dynamic.Interface, error)
+	makeClient          func() (kubernetes.Interface, error)
 }
 
 func (c *Config) Validate() error {
@@ -96,6 +99,18 @@ func (c *Config) Validate() error {
 	return nil
 }
 
+func (c *Config) getClient() (kubernetes.Interface, error) {
+	if c.makeClient != nil {
+		return c.makeClient()
+	}
+	client, err := k8sconfig.MakeClient(c.APIConfig)
+	if err != nil {
+		return nil, err
+	}
+
+	return client, nil
+}
+
 func (c *Config) getDiscoveryClient() (discovery.ServerResourcesInterface, error) {
 	if c.makeDiscoveryClient != nil {
 		return c.makeDiscoveryClient()

receiver/k8sobjectsreceiver/config_test.go

@@ -13,6 +13,8 @@ import (
 	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/confmap/confmaptest"
 	"k8s.io/apimachinery/pkg/runtime/schema"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/internal/k8sconfig"
 )
 
 func TestLoadConfig(t *testing.T) {
@@ -37,7 +39,7 @@ func TestLoadConfig(t *testing.T) {
 	err = component.ValidateConfig(cfg)
 	require.NoError(t, err)
 
-	expected := []*K8sObjectsConfig{
+	expectedObjects := []*K8sObjectsConfig{
 		{
 			Name:          "pods",
 			Mode:          PullMode,
@@ -63,7 +65,13 @@ func TestLoadConfig(t *testing.T) {
 			},
 		},
 	}
-	assert.EqualValues(t, expected, cfg.Objects)
+	expectedLleaerElection := k8sconfig.LeaderElectionConfig{
+		Enabled:          true,
+		LeaderElectionID: "e3385b9a.leader-election.opentelemetry-collector",
+	}
+
+	assert.EqualValues(t, expectedObjects, cfg.Objects)
+	assert.EqualValues(t, expectedLleaerElection, cfg.LeaderElection)
 
 }
 

receiver/k8sobjectsreceiver/factory.go

@@ -30,6 +30,10 @@ func createDefaultConfig() component.Config {
 		APIConfig: k8sconfig.APIConfig{
 			AuthType: k8sconfig.AuthTypeServiceAccount,
 		},
+		LeaderElection: k8sconfig.LeaderElectionConfig{
+			Enabled:          false,
+			LeaderElectionID: "e3385b9a.leader-election.opentelemetry-collector",
+		},
 	}
 }
 

receiver/k8sobjectsreceiver/factory_test.go

@@ -26,6 +26,10 @@ func TestDefaultConfig(t *testing.T) {
 		APIConfig: k8sconfig.APIConfig{
 			AuthType: k8sconfig.AuthTypeServiceAccount,
 		},
+		LeaderElection: k8sconfig.LeaderElectionConfig{
+			Enabled:          false,
+			LeaderElectionID: "e3385b9a.leader-election.opentelemetry-collector",
+		},
 	}, rCfg)
 }