[translator/loki] Convert dots to underscores in labels names

.chloggen/lokiexporter-dots-to-underscores-label-name-normalization.yaml

@@ -0,0 +1,19 @@
+# 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: translator/loki
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Normalize label names so they follow the Prometheus label names standard
+
+# One or more tracking issues related to the change
+issues: [14113]
+
+# (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: |
+  Loki doesn't support label names containing dots. |
+  Users had to convert dot-separated attributes into underscore-separated attributes before promoting them to Loki labels. |
+  From now on users can drop relabeling from their configuration. All dots in label names will be replaced with underscores automatically before sending request to Loki.

exporter/lokiexporter/README.md

@@ -33,26 +33,20 @@ attribute as label and the `resource` processor to give a hint to the Loki expor
 processors:
   attributes:
     actions:
-      - action: insert
-        key: event_domain
-        from_attribute: event.domain
       - action: insert
         key: loki.attribute.labels
-        value: event_domain
+        value: event.domain
 
   resource:
     attributes:
-      - action: insert
-        key: service_name
-        from_attribute: service.name
       - action: insert
         key: loki.resource.labels
-        value: service_name
+        value: service.name
 ```
 
-Currently, Loki does not support labels with dots.
-That’s why to add Loki label based on `event.domain` OTLP attribute we need to specify two actions. The first one inserts a new attribute `event_domain` from the OTLP attribute `event.domain`. The second one is a hint for Loki, specifying that the `event_domain` attribute should be placed as a Loki label.
-The same approach is applicable to placing Loki labels from resource attribute `service.name`.
+Currently, Loki does not support label names with dots. 
+That's why lokiexporter normalizes label names to follow Prometheus label names standard before sending requests to Loki.
+More information on label normalization could be found [here](../../pkg/translator/prometheus/README.md#Labels)
 
 Default labels:
 - `job=service.namespace/service.name`
@@ -98,10 +92,7 @@ processors:
     attributes:
     - action: insert
       key: loki.tenant
-      value: host_name
-    - action: insert
-      key: host_name
-      from_attribute: host.name
+      value: host.name
 ```
 
 In this case the value of the `host.name` resource attribute is used to group logs

exporter/lokiexporter/go.mod

@@ -39,6 +39,7 @@ require (
 	github.com/mitchellh/reflectwalk v1.0.2 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.2 // indirect
+	github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheus v0.74.0 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/rs/cors v1.8.3 // indirect
 	go.opencensus.io v0.24.0 // indirect
@@ -65,4 +66,6 @@ replace github.com/open-telemetry/opentelemetry-collector-contrib/internal/corei
 
 replace github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/loki => ../../pkg/translator/loki
 
+replace github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheus => ../../pkg/translator/prometheus
+
 retract v0.65.0

exporter/lokiexporter/next_exporter_test.go

@@ -51,7 +51,7 @@ func TestPushLogData(t *testing.T) {
 			hints: map[string]interface{}{
 				"loki.attribute.labels": "host.name",
 			},
-			expectedLabel: `{exporter="OTLP", host.name="guarana"}`,
+			expectedLabel: `{exporter="OTLP", host_name="guarana"}`,
 			expectedLine:  `{"traceid":"01020304000000000000000000000000","attributes":{"http.status":200}}`,
 		},
 		{
@@ -63,7 +63,7 @@ func TestPushLogData(t *testing.T) {
 			hints: map[string]interface{}{
 				"loki.resource.labels": "host.name",
 			},
-			expectedLabel: `{exporter="OTLP", host.name="guarana"}`,
+			expectedLabel: `{exporter="OTLP", host_name="guarana"}`,
 			expectedLine:  `{"traceid":"01020304000000000000000000000000","resources":{"region.az":"eu-west-1a"}}`,
 		},
 	}
@@ -169,11 +169,11 @@ func TestLogsToLokiRequestWithGroupingByTenant(t *testing.T) {
 				label string
 			}{
 				"1": {
-					label: `{exporter="OTLP", tenant.id="1"}`,
+					label: `{exporter="OTLP", tenant_id="1"}`,
 					line:  `{"attributes":{"http.status":200}}`,
 				},
 				"2": {
-					label: `{exporter="OTLP", tenant.id="2"}`,
+					label: `{exporter="OTLP", tenant_id="2"}`,
 					line:  `{"attributes":{"http.status":200}}`,
 				},
 			},
@@ -233,11 +233,11 @@ func TestLogsToLokiRequestWithGroupingByTenant(t *testing.T) {
 				label string
 			}{
 				"1": {
-					label: `{exporter="OTLP", tenant.id="1"}`,
+					label: `{exporter="OTLP", tenant_id="1"}`,
 					line:  `{"attributes":{"http.status":200}}`,
 				},
 				"2": {
-					label: `{exporter="OTLP", tenant.id="2"}`,
+					label: `{exporter="OTLP", tenant_id="2"}`,
 					line:  `{"attributes":{"http.status":200}}`,
 				},
 			},

pkg/translator/loki/go.mod

@@ -6,6 +6,7 @@ require (
 	github.com/go-logfmt/logfmt v0.5.1
 	github.com/grafana/loki/pkg/push v0.0.0-20230127072203-4e8cc8d71928
 	github.com/open-telemetry/opentelemetry-collector-contrib/internal/coreinternal v0.74.0
+	github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheus v0.74.0
 	github.com/prometheus/common v0.42.0
 	github.com/stretchr/testify v1.8.2
 	go.opentelemetry.io/collector/pdata v1.0.0-rc8
@@ -21,6 +22,7 @@ require (
 	github.com/modern-go/reflect2 v1.0.2 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/rogpeppe/go-internal v1.9.0 // indirect
+	go.opentelemetry.io/collector/featuregate v0.74.0 // indirect
 	go.uber.org/multierr v1.10.0 // indirect
 	golang.org/x/net v0.8.0 // indirect
 	golang.org/x/sys v0.6.0 // indirect
@@ -31,6 +33,10 @@ require (
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
 
+replace github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheus => ../../../pkg/translator/prometheus
+
 replace github.com/open-telemetry/opentelemetry-collector-contrib/internal/coreinternal => ../../../internal/coreinternal
 
+replace github.com/open-telemetry/opentelemetry-collector-contrib/internal/common => ../../../internal/common
+
 retract v0.65.0

pkg/translator/loki/logs_to_loki.go

@@ -22,6 +22,8 @@ import (
 	"github.com/prometheus/common/model"
 	"go.opentelemetry.io/collector/pdata/pcommon"
 	"go.opentelemetry.io/collector/pdata/plog"
+
+	prometheustranslator "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheus"
 )
 
 type PushRequest struct {
@@ -90,8 +92,16 @@ func LogsToLokiRequests(ld plog.Logs) map[string]PushRequest {
 
 				group.report.NumSubmitted++
 
+				processed := model.LabelSet{}
+				for label := range entry.Labels {
+					// Loki doesn't support dots in label names
+					// labelName is normalized label name to follow Prometheus label names standard
+					labelName := prometheustranslator.NormalizeLabel(string(label))
+					processed[model.LabelName(labelName)] = entry.Labels[label]
+				}
+
 				// create the stream name based on the labels
-				labels := entry.Labels.String()
+				labels := processed.String()
 				if stream, ok := group.streams[labels]; ok {
 					stream.Entries = append(stream.Entries, *entry.Entry)
 					continue

pkg/translator/loki/logs_to_loki_test.go

@@ -58,7 +58,7 @@ func TestLogsToLokiRequestWithGroupingByTenant(t *testing.T) {
 					PushRequest: &push.PushRequest{
 						Streams: []push.Stream{
 							{
-								Labels: `{exporter="OTLP", tenant.id="1"}`,
+								Labels: `{exporter="OTLP", tenant_id="1"}`,
 								Entries: []push.Entry{
 									{
 										Line: `{"attributes":{"http.status":200}}`,
@@ -71,7 +71,7 @@ func TestLogsToLokiRequestWithGroupingByTenant(t *testing.T) {
 					PushRequest: &push.PushRequest{
 						Streams: []push.Stream{
 							{
-								Labels: `{exporter="OTLP", tenant.id="2"}`,
+								Labels: `{exporter="OTLP", tenant_id="2"}`,
 								Entries: []push.Entry{
 									{
 										Line: `{"attributes":{"http.status":200}}`,
@@ -110,7 +110,7 @@ func TestLogsToLokiRequestWithGroupingByTenant(t *testing.T) {
 					PushRequest: &push.PushRequest{
 						Streams: []push.Stream{
 							{
-								Labels: `{exporter="OTLP", tenant.id="11"}`,
+								Labels: `{exporter="OTLP", tenant_id="11"}`,
 								Entries: []push.Entry{
 									{
 										Line: `{"attributes":{"http.status":200}}`,
@@ -123,7 +123,7 @@ func TestLogsToLokiRequestWithGroupingByTenant(t *testing.T) {
 					PushRequest: &push.PushRequest{
 						Streams: []push.Stream{
 							{
-								Labels: `{exporter="OTLP", tenant.id="12"}`,
+								Labels: `{exporter="OTLP", tenant_id="12"}`,
 								Entries: []push.Entry{
 									{
 										Line: `{"attributes":{"http.status":200}}`,
@@ -196,7 +196,7 @@ func TestLogsToLokiRequestWithGroupingByTenant(t *testing.T) {
 					PushRequest: &push.PushRequest{
 						Streams: []push.Stream{
 							{
-								Labels: `{exporter="OTLP", tenant.id="21"}`,
+								Labels: `{exporter="OTLP", tenant_id="21"}`,
 								Entries: []push.Entry{
 									{
 										Line: `{"attributes":{"http.status":200}}`,
@@ -209,7 +209,7 @@ func TestLogsToLokiRequestWithGroupingByTenant(t *testing.T) {
 					PushRequest: &push.PushRequest{
 						Streams: []push.Stream{
 							{
-								Labels: `{exporter="OTLP", tenant.id="22"}`,
+								Labels: `{exporter="OTLP", tenant_id="22"}`,
 								Entries: []push.Entry{
 									{
 										Line: `{"attributes":{"http.status":200}}`,
@@ -265,7 +265,7 @@ func TestLogsToLokiRequestWithoutTenant(t *testing.T) {
 			hints: map[string]interface{}{
 				hintAttributes: "host.name",
 			},
-			expectedLabel: `{exporter="OTLP", host.name="guarana"}`,
+			expectedLabel: `{exporter="OTLP", host_name="guarana"}`,
 			expectedLines: []string{
 				`{"traceid":"01000000000000000000000000000000","attributes":{"http.status":200}}`,
 				`{"traceid":"02000000000000000000000000000000","attributes":{"http.status":200}}`,
@@ -281,7 +281,7 @@ func TestLogsToLokiRequestWithoutTenant(t *testing.T) {
 			hints: map[string]interface{}{
 				hintResources: "host.name",
 			},
-			expectedLabel: `{exporter="OTLP", host.name="guarana"}`,
+			expectedLabel: `{exporter="OTLP", host_name="guarana"}`,
 			expectedLines: []string{
 				`{"traceid":"01000000000000000000000000000000","resources":{"region.az":"eu-west-1a"}}`,
 				`{"traceid":"02000000000000000000000000000000","resources":{"region.az":"eu-west-1a"}}`,
@@ -298,7 +298,7 @@ func TestLogsToLokiRequestWithoutTenant(t *testing.T) {
 				hintAttributes: "host.name",
 				hintFormat:     formatLogfmt,
 			},
-			expectedLabel: `{exporter="OTLP", host.name="guarana"}`,
+			expectedLabel: `{exporter="OTLP", host_name="guarana"}`,
 			expectedLines: []string{
 				`traceID=01000000000000000000000000000000 attribute_http.status=200`,
 				`traceID=02000000000000000000000000000000 attribute_http.status=200`,