fix: fallback to gauge for protofmt-based negotiations

Fallback to `gauge` metric type when the negotiated content-type is `protofmt`-based, since Prometheus' protobuf machinery does not recognize all OpenMetrics types (`info` and `statesets` in this context). Signed-off-by: Pranshu Srivastava <rexagod@gmail.com>
kubernetes · Dec 13, 2023 · d4a0dfb · d4a0dfb
1 parent 14e935a
commit d4a0dfb
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Showing 2 changed files with 19 additions and 4 deletions.
diff --git a/pkg/metrics_store/metrics_writer.go b/pkg/metrics_store/metrics_writer.go
@@ -19,6 +19,11 @@ package metricsstore
 import (
 	"fmt"
 	"io"
+	"strings"
+
+	"github.com/prometheus/common/expfmt"
+
+	"k8s.io/kube-state-metrics/v2/pkg/metric"
 )
 
 // MetricsWriterList represent a list of MetricsWriter
@@ -82,13 +87,22 @@ func (m MetricsWriter) WriteAll(w io.Writer) error {
 	return nil
 }
 
-// SanitizeHeaders removes duplicate headers from the given MetricsWriterList for the same family (generated through CRS).
-// These are expected to be consecutive since G** resolution generates groups of similar metrics with same headers before moving onto the next G** spec in the CRS configuration.
-func SanitizeHeaders(writers MetricsWriterList) MetricsWriterList {
+// SanitizeHeaders sanitizes the headers of the given MetricsWriterList.
+func SanitizeHeaders(contentType string, writers MetricsWriterList) MetricsWriterList {
 	var lastHeader string
 	for _, writer := range writers {
 		if len(writer.stores) > 0 {
 			for i, header := range writer.stores[0].headers {
+				// If the requested content type was proto-based, replace the type with "gauge", as "info" and "statesets" are not recognized by Prometheus' protobuf machinery.
+				if strings.HasPrefix(contentType, expfmt.ProtoFmt) &&
+					strings.HasPrefix(header, "# HELP") &&
+					(strings.HasSuffix(header, " "+string(metric.Info)) || strings.HasSuffix(header, " "+string(metric.StateSet))) {
+					typeStringWithoutTypePaddedIndex := strings.LastIndex(header, " ")
+					typeStringWithoutType := header[:typeStringWithoutTypePaddedIndex]
+					writer.stores[0].headers[i] = typeStringWithoutType + " " + string(metric.Gauge)
+				}
+				// Removes duplicate headers from the given MetricsWriterList for the same family (generated through CRS).
+				// These are expected to be consecutive since G** resolution generates groups of similar metrics with same headers before moving onto the next G** spec in the CRS configuration.
 				if header == lastHeader {
 					writer.stores[0].headers[i] = ""
 				} else {

diff --git a/pkg/metricshandler/metrics_handler.go b/pkg/metricshandler/metrics_handler.go
@@ -187,6 +187,7 @@ func (m *MetricsHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	var writer io.Writer = w
 
 	contentType := expfmt.NegotiateIncludingOpenMetrics(r.Header)
+	gotContentType := contentType
 
 	// We do not support protobuf at the moment. Fall back to FmtText if the negotiated exposition format is not FmtOpenMetrics See: https://github.com/kubernetes/kube-state-metrics/issues/2022
 	if contentType != expfmt.FmtOpenMetrics_1_0_0 && contentType != expfmt.FmtOpenMetrics_0_0_1 {
@@ -208,7 +209,7 @@ func (m *MetricsHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
-	m.metricsWriters = metricsstore.SanitizeHeaders(m.metricsWriters)
+	m.metricsWriters = metricsstore.SanitizeHeaders(string(gotContentType), m.metricsWriters)
 	for _, w := range m.metricsWriters {
 		err := w.WriteAll(writer)
 		if err != nil {