fix: consider no match as a read error

internal/exporter.go

@@ -3,6 +3,7 @@ package internal
 import (
 	"context"
 	"crypto/x509/pkix"
+	"errors"
 	"fmt"
 	"io/fs"
 	"net"
@@ -259,15 +260,15 @@ func (exporter *Exporter) getAllMatchingCertificates(pattern string) ([]*certifi
 		walk,
 		doublestar.WithFilesOnly(),
 		doublestar.WithFailOnIOErrors(),
+		doublestar.WithFailOnPatternNotExist(),
 		// doublestar.WithNoFollow(),
-		// doublestar.WithFailOnPatternNotExist(),
 	)
 	if err != nil {
-		return nil, err
-	}
+		if errors.Is(err, doublestar.ErrPatternNotExist) {
+			return nil, errors.New("no files match \"" + pattern + "\"")
+		}
 
-	if len(output) == 0 {
-		log.Warnln("no files match pattern \"" + pattern + "\"")
+		return nil, err
 	}
 
 	return output, nil

internal/exporter_test.go

@@ -672,6 +672,20 @@ func TestExposeLabels(t *testing.T) {
 }
 
 func TestGlobbing(t *testing.T) {
+	// no pattern at all
+	testRequest(t, &Exporter{
+		Files: []string{"does-not-exist/toto"},
+	}, func(metrics []model.MetricFamily) {
+		foundMetrics := getMetricsForName(metrics, "x509_cert_expired")
+		assert.Len(t, foundMetrics, 0)
+		foundNbMetrics := getMetricsForName(metrics, "x509_cert_not_before")
+		assert.Len(t, foundNbMetrics, 0)
+		foundNaMetrics := getMetricsForName(metrics, "x509_cert_not_after")
+		assert.Len(t, foundNaMetrics, 0)
+		errMetric := getMetricsForName(metrics, "x509_read_errors")
+		assert.Equal(t, 1., errMetric[0].GetGauge().GetValue())
+	})
+
 	// no matches
 	testRequest(t, &Exporter{
 		Files: []string{"does-not-exist/**"},
@@ -683,7 +697,7 @@ func TestGlobbing(t *testing.T) {
 		foundNaMetrics := getMetricsForName(metrics, "x509_cert_not_after")
 		assert.Len(t, foundNaMetrics, 0)
 		errMetric := getMetricsForName(metrics, "x509_read_errors")
-		assert.Equal(t, 0., errMetric[0].GetGauge().GetValue())
+		assert.Equal(t, 1., errMetric[0].GetGauge().GetValue())
 	})
 
 	// single star match