Loki: Add dashboard and panel names as headers (#92096)

* feat(nameHeaders): add feature flag

* add safe parsing of headers

* use headers in loki datasource

* Loki: add option to pass headers to Loki

* Loki: add datasource tests for dashboard names

* cleanup

* DataSourceWithBackend: add test

* rename to `sanitizeHeader`

* Loki: add condition when to add headers

* Loki: add e2e tests

* Loki: change test name

pkg/tsdb/loki/loki.go

@@ -22,6 +22,7 @@ import (
 	"github.com/grafana/grafana-plugin-sdk-go/backend/httpclient"
 
 	"github.com/grafana/grafana/pkg/infra/tracing"
+	"github.com/grafana/grafana/pkg/services/contexthandler"
 	"github.com/grafana/grafana/pkg/services/featuremgmt"
 	ngalertmodels "github.com/grafana/grafana/pkg/services/ngalert/models"
 	"github.com/grafana/grafana/pkg/tsdb/loki/kinds/dataquery"
@@ -49,13 +50,13 @@ func ProvideService(httpClientProvider *httpclient.Provider, tracer tracing.Trac
 
 var (
 	legendFormat = regexp.MustCompile(`\{\{\s*(.+?)\s*\}\}`)
-)
 
-// Used in logging to mark a stage
-var (
 	stagePrepareRequest  = "prepareRequest"
 	stageDatabaseRequest = "databaseRequest"
 	stageParseResponse   = "parseResponse"
+
+	dashboardTitleHeader = "X-Dashboard-Title"
+	panelTitleHeader     = "X-Panel-Title"
 )
 
 type datasourceInfo struct {
@@ -163,9 +164,30 @@ func (s *Service) QueryData(ctx context.Context, req *backend.QueryDataRequest)
 		logsDataplane:   isFeatureEnabled(ctx, featuremgmt.FlagLokiLogsDataplane),
 	}
 
+	if isFeatureEnabled(ctx, featuremgmt.FlagLokiSendDashboardPanelNames) {
+		s.applyHeaders(ctx, req)
+	}
+
 	return queryData(ctx, req, dsInfo, responseOpts, s.tracer, logger, isFeatureEnabled(ctx, featuremgmt.FlagLokiRunQueriesInParallel), isFeatureEnabled(ctx, featuremgmt.FlagLokiStructuredMetadata))
 }
 
+func (s *Service) applyHeaders(ctx context.Context, req backend.ForwardHTTPHeaders) {
+	reqCtx := contexthandler.FromContext(ctx)
+	if req == nil || reqCtx == nil || reqCtx.Req == nil {
+		return
+	}
+
+	var hList = []string{dashboardTitleHeader, panelTitleHeader}
+
+	for _, hName := range hList {
+		hVal := reqCtx.Req.Header.Get(hName)
+		if hVal == "" {
+			continue
+		}
+		req.SetHTTPHeader(hName, hVal)
+	}
+}
+
 func queryData(ctx context.Context, req *backend.QueryDataRequest, dsInfo *datasourceInfo, responseOpts ResponseOpts, tracer tracing.Tracer, plog log.Logger, runInParallel bool, requestStructuredMetadata bool) (*backend.QueryDataResponse, error) {
 	result := backend.NewQueryDataResponse()