Fix logs cluster (#1716)

* fix clustering for logs

* Simplify code.

* Add changelog.

CHANGELOG.md

@@ -48,6 +48,9 @@ Main (unreleased)
 - Fixed an issue with `loki.process` where configuration could be reloaded even if there
   were no changes. (@ptodev, @thampiotr)
 
+- Fix issue where `loki.source.kubernetes` took into account all labels, instead of specific logs labels. Resulting in duplication. (@mattdurham)
+
+
 ### Other changes
 
 - Small fix in UI stylesheet to fit more content into visible table area. (@defanator)

docs/sources/reference/components/loki/loki.source.kubernetes.md

@@ -145,6 +145,20 @@ If {{< param "PRODUCT_NAME" >}} is _not_ running in clustered mode, then the blo
 `loki.source.kubernetes` collects logs from every target it receives in its
 arguments.
 
+Clustering only looks at the following labels for determining the shard key:
+* `__pod_namespace__`
+* `__pod_name__`
+* `__pod_container_name__`
+* `__pod_uid__`
+* `__meta_kubernetes_namespace`
+* `__meta_kubernetes_pod_name`
+* `__meta_kubernetes_pod_container_name`
+* `__meta_kubernetes_pod_uid`
+* `container`
+* `pod`
+* `job`
+* `namespace`
+
 [using clustering]: ../../../../get-started/clustering/
 
 ## Exported fields

internal/component/discovery/discovery.go

@@ -2,6 +2,7 @@ package discovery
 
 import (
 	"context"
+	"slices"
 	"sort"
 	"strings"
 	"sync"
@@ -41,6 +42,17 @@ func (t Target) NonMetaLabels() labels.Labels {
 	return lset
 }
 
+func (t Target) SpecificLabels(lbls []string) labels.Labels {
+	var lset labels.Labels
+	for k, v := range t {
+		if slices.Contains(lbls, k) {
+			lset = append(lset, labels.Label{Name: k, Value: v})
+		}
+	}
+	sort.Sort(lset)
+	return lset
+}
+
 // Exports holds values which are exported by all discovery components.
 type Exports struct {
 	Targets []Target `alloy:"targets,attr"`

internal/component/discovery/distributed_targets.go

@@ -19,6 +19,13 @@ type DistributedTargets struct {
 // NewDistributedTargets creates the abstraction that allows components to
 // dynamically shard targets between components.
 func NewDistributedTargets(clusteringEnabled bool, cluster cluster.Cluster, allTargets []Target) *DistributedTargets {
+	return NewDistributedTargetsWithCustomLabels(clusteringEnabled, cluster, allTargets, nil)
+}
+
+// NewDistributedTargetsWithCustomLabels creates the abstraction that allows components to
+// dynamically shard targets between components. Passing in labels will limit the sharding to only use those labels for computing the hash key.
+// Passing in nil or empty array means look at all labels.
+func NewDistributedTargetsWithCustomLabels(clusteringEnabled bool, cluster cluster.Cluster, allTargets []Target, labels []string) *DistributedTargets {
 	if !clusteringEnabled || cluster == nil {
 		cluster = disabledCluster{}
 	}
@@ -32,8 +39,20 @@ func NewDistributedTargets(clusteringEnabled bool, cluster cluster.Cluster, allT
 	localTargetKeys := make([]shard.Key, 0, localCap)
 	remoteTargetKeys := make(map[shard.Key]struct{}, len(allTargets)-localCap)
 
+	// Need to handle duplicate entries.
+	singlular := make(map[shard.Key]struct{})
 	for _, tgt := range allTargets {
-		targetKey := keyFor(tgt)
+		var targetKey shard.Key
+		// If we have no custom labels check all non-meta labels.
+		if len(labels) == 0 {
+			targetKey = keyFor(tgt)
+		} else {
+			targetKey = keyForLabels(tgt, labels)
+		}
+		if _, ok := singlular[targetKey]; ok {
+			continue
+		}
+		singlular[targetKey] = struct{}{}
 		peers, err := cluster.Lookup(targetKey, 1, shard.OpReadWrite)
 		belongsToLocal := err != nil || len(peers) == 0 || peers[0].Self
 
@@ -57,6 +76,10 @@ func (dt *DistributedTargets) LocalTargets() []Target {
 	return dt.localTargets
 }
 
+func (dt *DistributedTargets) TargetCount() int {
+	return len(dt.localTargetKeys) + len(dt.remoteTargetKeys)
+}
+
 // MovedToRemoteInstance returns the set of local targets from prev
 // that are no longer local in dt, indicating an active target has moved.
 // Only targets which exist in both prev and dt are returned. If prev
@@ -79,6 +102,10 @@ func keyFor(tgt Target) shard.Key {
 	return shard.Key(tgt.NonMetaLabels().Hash())
 }
 
+func keyForLabels(tgt Target, lbls []string) shard.Key {
+	return shard.Key(tgt.SpecificLabels(lbls).Hash())
+}
+
 type disabledCluster struct{}
 
 var _ cluster.Cluster = disabledCluster{}

internal/component/loki/source/kubernetes/kubernetes.go

@@ -187,7 +187,7 @@ func (c *Component) Update(args component.Arguments) error {
 }
 
 func (c *Component) resyncTargets(targets []discovery.Target) {
-	distTargets := discovery.NewDistributedTargets(c.args.Clustering.Enabled, c.cluster, targets)
+	distTargets := discovery.NewDistributedTargetsWithCustomLabels(c.args.Clustering.Enabled, c.cluster, targets, kubetail.ClusteringLabels)
 	targets = distTargets.LocalTargets()
 
 	tailTargets := make([]*kubetail.Target, 0, len(targets))

internal/component/loki/source/kubernetes/kubernetes_test.go

@@ -1,6 +1,9 @@
 package kubernetes
 
 import (
+	"github.com/grafana/alloy/internal/component/discovery"
+	"github.com/grafana/alloy/internal/component/loki/source/kubernetes/kubetail"
+	"github.com/grafana/alloy/internal/service/cluster"
 	"testing"
 
 	"github.com/grafana/alloy/syntax"
@@ -43,3 +46,32 @@ func TestBadAlloyConfig(t *testing.T) {
 	err := syntax.Unmarshal([]byte(exampleAlloyConfig), &args)
 	require.ErrorContains(t, err, "at most one of basic_auth, authorization, oauth2, bearer_token & bearer_token_file must be configured")
 }
+
+func TestClusteringDuplicateAddress(t *testing.T) {
+	// Since loki.source.kubernetes looks up by pod name, if we dont use the special NewDistributedTargetsWithCustomLabels
+	// then we can pull logs multiple times if the address is reused for the port. This works fine for scraping since those are different
+	// endpoints, but from a log perspective they are the same logs.
+	distTargets := discovery.NewDistributedTargetsWithCustomLabels(
+		true,
+		cluster.Mock(),
+		[]discovery.Target{
+			{
+				"__address__": "localhost:9090",
+				"container":   "alloy",
+				"pod":         "grafana-k8s-monitoring-alloy-0",
+				"job":         "integrations/alloy",
+				"namespace":   "default",
+			},
+			{
+				"__address__": "localhost:8080",
+				"container":   "alloy",
+				"pod":         "grafana-k8s-monitoring-alloy-0",
+				"job":         "integrations/alloy",
+				"namespace":   "default",
+			},
+		},
+		kubetail.ClusteringLabels,
+	)
+	require.True(t, distTargets.TargetCount() == 1)
+
+}

internal/component/loki/source/kubernetes/kubetail/target.go

@@ -25,6 +25,21 @@ const (
 	kubePodUID           = "__meta_kubernetes_pod_uid"
 )
 
+var ClusteringLabels = []string{
+	LabelPodNamespace,
+	LabelPodName,
+	LabelPodContainerName,
+	LabelPodUID,
+	kubePodNamespace,
+	kubePodName,
+	kubePodContainerName,
+	kubePodUID,
+	"container",
+	"pod",
+	"job",
+	"namespace",
+}
+
 // Target represents an individual container being tailed for logs.
 type Target struct {
 	origLabels   labels.Labels // Original discovery labels