promtail: Support set tenant id from labels

clients/pkg/logentry/stages/tenant.go

@@ -14,8 +14,8 @@ import (
 )
 
 const (
-	ErrTenantStageEmptySourceOrValue        = "source or value config are required"
-	ErrTenantStageConflictingSourceAndValue = "source and value are mutually exclusive: you should set source or value but not both"
+	ErrTenantStageEmptyLabelSourceOrValue        = "label, source or value config are required"
+	ErrTenantStageConflictingLabelSourceAndValue = "label, source and value are mutually exclusive: you should set source, value or label but not all"
 )
 
 type tenantStage struct {
@@ -24,18 +24,19 @@ type tenantStage struct {
 }
 
 type TenantConfig struct {
+	Label  string `mapstructure:"label"`
 	Source string `mapstructure:"source"`
 	Value  string `mapstructure:"value"`
 }
 
 // validateTenantConfig validates the tenant stage configuration
 func validateTenantConfig(c TenantConfig) error {
-	if c.Source == "" && c.Value == "" {
-		return errors.New(ErrTenantStageEmptySourceOrValue)
+	if c.Source == "" && c.Value == "" && c.Label == "" {
+		return errors.New(ErrTenantStageEmptyLabelSourceOrValue)
 	}
 
-	if c.Source != "" && c.Value != "" {
-		return errors.New(ErrTenantStageConflictingSourceAndValue)
+	if c.Source != "" && c.Value != "" || c.Label != "" && c.Value != "" || c.Source != "" && c.Label != "" {
+		return errors.New(ErrTenantStageConflictingLabelSourceAndValue)
 	}
 
 	return nil
@@ -67,6 +68,8 @@ func (s *tenantStage) Process(labels model.LabelSet, extracted map[string]interf
 	// Get tenant ID from source or configured value
 	if s.cfg.Source != "" {
 		tenantID = s.getTenantFromSourceField(extracted)
+	} else if s.cfg.Label != "" {
+		tenantID = s.getTenantFromLabel(labels)
 	} else {
 		tenantID = s.cfg.Value
 	}
@@ -105,3 +108,17 @@ func (s *tenantStage) getTenantFromSourceField(extracted map[string]interface{})
 
 	return tenantID
 }
+
+func (s *tenantStage) getTenantFromLabel(labels model.LabelSet) string {
+	// Get the tenant ID from the label map
+	tenantID, ok := labels[model.LabelName(s.cfg.Label)]
+
+	if !ok {
+		if Debug {
+			level.Debug(s.logger).Log("msg", "the tenant source does not exist in the labels", "source", s.cfg.Source)
+		}
+		return ""
+	}
+
+	return string(tenantID)
+}

clients/pkg/logentry/stages/tenant_test.go

@@ -18,7 +18,7 @@ import (
 	util_log "github.com/grafana/loki/pkg/util/log"
 )
 
-var testTenantYaml = `
+var testTenantYamlExtractedData = `
 pipeline_stages:
 - json:
     expressions:
@@ -40,7 +40,7 @@ func TestPipelineWithMissingKey_Tenant(t *testing.T) {
 	var buf bytes.Buffer
 	w := log.NewSyncWriter(&buf)
 	logger := log.NewLogfmtLogger(w)
-	pl, err := NewPipeline(logger, loadConfig(testTenantYaml), nil, prometheus.DefaultRegisterer)
+	pl, err := NewPipeline(logger, loadConfig(testTenantYamlExtractedData), nil, prometheus.DefaultRegisterer)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -74,26 +74,54 @@ func TestTenantStage_Validation(t *testing.T) {
 		},
 		"should fail on missing source and value": {
 			config:      &TenantConfig{},
-			expectedErr: lokiutil.StringRef(ErrTenantStageEmptySourceOrValue),
+			expectedErr: lokiutil.StringRef(ErrTenantStageEmptyLabelSourceOrValue),
 		},
 		"should fail on empty source": {
 			config: &TenantConfig{
 				Source: "",
 			},
-			expectedErr: lokiutil.StringRef(ErrTenantStageEmptySourceOrValue),
+			expectedErr: lokiutil.StringRef(ErrTenantStageEmptyLabelSourceOrValue),
 		},
 		"should fail on empty value": {
 			config: &TenantConfig{
 				Value: "",
 			},
-			expectedErr: lokiutil.StringRef(ErrTenantStageEmptySourceOrValue),
+			expectedErr: lokiutil.StringRef(ErrTenantStageEmptyLabelSourceOrValue),
+		},
+		"should fail on empty label": {
+			config: &TenantConfig{
+				Label: "",
+			},
+			expectedErr: lokiutil.StringRef(ErrTenantStageEmptyLabelSourceOrValue),
 		},
 		"should fail on both source and value set": {
 			config: &TenantConfig{
 				Source: "tenant",
 				Value:  "team-a",
 			},
-			expectedErr: lokiutil.StringRef(ErrTenantStageConflictingSourceAndValue),
+			expectedErr: lokiutil.StringRef(ErrTenantStageConflictingLabelSourceAndValue),
+		},
+		"should fail on both source and label set": {
+			config: &TenantConfig{
+				Source: "tenant",
+				Label:  "team-a",
+			},
+			expectedErr: lokiutil.StringRef(ErrTenantStageConflictingLabelSourceAndValue),
+		},
+		"should fail on both label and value set": {
+			config: &TenantConfig{
+				Label: "tenant",
+				Value: "team-a",
+			},
+			expectedErr: lokiutil.StringRef(ErrTenantStageConflictingLabelSourceAndValue),
+		},
+		"should fail on all set": {
+			config: &TenantConfig{
+				Label:  "tenant",
+				Source: "tenant",
+				Value:  "team-a",
+			},
+			expectedErr: lokiutil.StringRef(ErrTenantStageConflictingLabelSourceAndValue),
 		},
 	}
 
@@ -141,6 +169,12 @@ func TestTenantStage_Process(t *testing.T) {
 			inputExtracted: map[string]interface{}{"tenant_id": "bar"},
 			expectedTenant: lokiutil.StringRef("bar"),
 		},
+		"should set the tenant if the label is defined in the label map": {
+			config:         &TenantConfig{Label: "tenant_id"},
+			inputLabels:    model.LabelSet{"tenant_id": "bar"},
+			inputExtracted: map[string]interface{}{},
+			expectedTenant: lokiutil.StringRef("bar"),
+		},
 		"should override the tenant if the source field is defined in the extracted map": {
 			config:         &TenantConfig{Source: "tenant_id"},
 			inputLabels:    model.LabelSet{client.ReservedLabelTenantID: "foo"},

docs/sources/clients/promtail/stages/tenant.md

@@ -13,9 +13,13 @@ be used.
 
 ```yaml
 tenant:
-  # Name from extracted data to whose value should be set as tenant ID.
-  # Either source or value config option is required, but not both (they
+  # Either label, source or value config option is required, but not all (they
   # are mutually exclusive).
+
+  # Name from labels to whose value should be set as tenant ID.
+  [ label: <string> ]
+
+  # Name from extracted data to whose value should be set as tenant ID.
   [ source: <string> ]
 
   # Value to use to set the tenant ID when this stage is executed. Useful
@@ -81,3 +85,28 @@ The pipeline would:
 1. Process the `match` stage checking if the `{app="api"}` selector matches
    and - whenever it matches - run the sub stages. The `tenant` sub stage
    would override the tenant with the value `"team-api"`.
+
+### Example: extract the tenant ID from kubernetes sd
+
+```yaml
+scrape_configs:
+  - job_name: kubernetes-pods-name
+
+    kubernetes_sd_configs:
+      - role: pod
+
+    relabel_configs:
+      - action: replace
+        source_labels:
+          - __meta_kubernetes_namespace
+        target_label: namespace
+
+    pipeline_stages:
+    - match:
+        selector: '{namespace=".+"}'
+        stages:
+          - tenant:
+              label: "namespace"
+    - output:
+         source: message
+```