pkg/metrics_store: add error handling to WriteAll

Signed-off-by: Damien Grisonnet <[email protected]>

Author: dgrisonnet

pkg/metrics_store/metrics_store_test.go

@@ -82,7 +82,10 @@ func TestObjectsSameNameDifferentNamespaces(t *testing.T) {
 
 	w := strings.Builder{}
 	mw := NewMetricsWriter(ms)
-	mw.WriteAll(&w)
+	err := mw.WriteAll(&w)
+	if err != nil {
+		t.Fatalf("failed to write metrics: %v", err)
+	}
 	m := w.String()
 
 	for _, id := range serviceIDS {

pkg/metrics_store/metrics_writer.go

@@ -16,7 +16,10 @@ limitations under the License.
 
 package metricsstore
 
-import "io"
+import (
+	"fmt"
+	"io"
+)
 
 // MetricsWriterList represent a list of MetricsWriter
 type MetricsWriterList []*MetricsWriter
@@ -43,9 +46,9 @@ func NewMetricsWriter(stores ...*MetricsStore) *MetricsWriter {
 //
 // WriteAll writes metrics so that the ones with the same name
 // are grouped together when written out.
-func (m MetricsWriter) WriteAll(w io.Writer) {
+func (m MetricsWriter) WriteAll(w io.Writer) error {
 	if len(m.stores) == 0 {
-		return
+		return nil
 	}
 
 	for _, s := range m.stores {
@@ -56,12 +59,19 @@ func (m MetricsWriter) WriteAll(w io.Writer) {
 	}
 
 	for i, help := range m.stores[0].headers {
-		w.Write([]byte(help))
-		w.Write([]byte{'\n'})
+		_, err := w.Write([]byte(help + "\n"))
+		if err != nil {
+			return fmt.Errorf("failed to write help text: %v", err)
+		}
+
 		for _, s := range m.stores {
 			for _, metricFamilies := range s.metrics {
-				w.Write(metricFamilies[i])
+				_, err := w.Write(metricFamilies[i])
+				if err != nil {
+					return fmt.Errorf("failed to write metrics family: %v", err)
+				}
 			}
 		}
 	}
+	return nil
 }

pkg/metrics_store/metrics_writer_test.go

@@ -85,7 +85,10 @@ func TestWriteAllWithSingleStore(t *testing.T) {
 
 	multiNsWriter := metricsstore.NewMetricsWriter(store)
 	w := strings.Builder{}
-	multiNsWriter.WriteAll(&w)
+	err := multiNsWriter.WriteAll(&w)
+	if err != nil {
+		t.Fatalf("failed to write metrics: %v", err)
+	}
 	result := w.String()
 
 	resultLines := strings.Split(strings.TrimRight(result, "\n"), "\n")
@@ -194,7 +197,10 @@ func TestWriteAllWithMultipleStores(t *testing.T) {
 
 	multiNsWriter := metricsstore.NewMetricsWriter(s1, s2)
 	w := strings.Builder{}
-	multiNsWriter.WriteAll(&w)
+	err := multiNsWriter.WriteAll(&w)
+	if err != nil {
+		t.Fatalf("failed to write metrics: %v", err)
+	}
 	result := w.String()
 
 	resultLines := strings.Split(strings.TrimRight(result, "\n"), "\n")

pkg/metricshandler/metrics_handler.go

@@ -200,7 +200,10 @@ func (m *MetricsHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 
 	for _, w := range m.metricsWriters {
-		w.WriteAll(writer)
+		err := w.WriteAll(writer)
+		if err != nil {
+			klog.ErrorS(err, "Failed to write metrics")
+		}
 	}
 
 	// In case we gzipped the response, we have to close the writer.

tests/lib/lib_test.go

@@ -56,7 +56,10 @@ func TestAsLibrary(t *testing.T) {
 
 	w := strings.Builder{}
 	mw := metricsstore.NewMetricsWriter(c)
-	mw.WriteAll(&w)
+	err = mw.WriteAll(&w)
+	if err != nil {
+		t.Fatalf("failed to write metrics: %v", err)
+	}
 	m := w.String()
 
 	if !strings.Contains(m, service.ObjectMeta.Name) {