OTLPConfig.UnmarshalYAML: Return error on invalid input

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>

config/config.go

@@ -19,7 +19,6 @@ import (
 	"net/url"
 	"os"
 	"path/filepath"
-	"slices"
 	"sort"
 	"strconv"
 	"strings"
@@ -1324,17 +1323,20 @@ func (c *OTLPConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	}
 
 	seen := map[string]struct{}{}
-	i := 0
-	for i < len(c.PromoteResourceAttributes) {
-		s := strings.TrimSpace(c.PromoteResourceAttributes[i])
-		if _, exists := seen[s]; exists {
-			c.PromoteResourceAttributes = slices.Delete(c.PromoteResourceAttributes, i, i+1)
+	var err error
+	for i, attr := range c.PromoteResourceAttributes {
+		attr = strings.TrimSpace(attr)
+		if attr == "" {
+			err = errors.Join(err, fmt.Errorf("empty promoted OTel resource attribute"))
+			continue
+		}
+		if _, exists := seen[attr]; exists {
+			err = errors.Join(err, fmt.Errorf("duplicated promoted OTel resource attribute %q", attr))
 			continue
 		}
 
-		seen[s] = struct{}{}
-		c.PromoteResourceAttributes[i] = s
-		i++
+		seen[attr] = struct{}{}
+		c.PromoteResourceAttributes[i] = attr
 	}
-	return nil
+	return err
 }

config/config_test.go

@@ -1478,15 +1478,23 @@ func TestRemoteWriteRetryOnRateLimit(t *testing.T) {
 }
 
 func TestOTLPSanitizeResourceAttributes(t *testing.T) {
-	want, err := LoadFile(filepath.Join("testdata", "otlp_sanitize_resource_attributes.good.yml"), false, false, log.NewNopLogger())
-	require.NoError(t, err)
-
-	out, err := yaml.Marshal(want)
-	require.NoError(t, err)
-	var got Config
-	require.NoError(t, yaml.UnmarshalStrict(out, &got))
-
-	require.Equal(t, []string{"k8s.cluster.name", "k8s.job.name", "k8s.namespace.name"}, got.OTLPConfig.PromoteResourceAttributes)
+	t.Run("good config", func(t *testing.T) {
+		want, err := LoadFile(filepath.Join("testdata", "otlp_sanitize_resource_attributes.good.yml"), false, false, log.NewNopLogger())
+		require.NoError(t, err)
+
+		out, err := yaml.Marshal(want)
+		require.NoError(t, err)
+		var got Config
+		require.NoError(t, yaml.UnmarshalStrict(out, &got))
+
+		require.Equal(t, []string{"k8s.cluster.name", "k8s.job.name", "k8s.namespace.name"}, got.OTLPConfig.PromoteResourceAttributes)
+	})
+
+	t.Run("bad config", func(t *testing.T) {
+		_, err := LoadFile(filepath.Join("testdata", "otlp_sanitize_resource_attributes.bad.yml"), false, false, log.NewNopLogger())
+		require.ErrorContains(t, err, `duplicated promoted OTel resource attribute "k8s.job.name"`)
+		require.ErrorContains(t, err, `empty promoted OTel resource attribute`)
+	})
 }
 
 func TestLoadConfig(t *testing.T) {

config/testdata/otlp_sanitize_resource_attributes.bad.yml

@@ -0,0 +1,2 @@
+otlp:
+  promote_resource_attributes: ["k8s.cluster.name", " k8s.job.name ", "k8s.namespace.name", "k8s.job.name", ""]

config/testdata/otlp_sanitize_resource_attributes.good.yml

@@ -1,2 +1,2 @@
 otlp:
-  promote_resource_attributes: ["k8s.cluster.name", "k8s.job.name", "k8s.namespace.name", " k8s.job.name "]
+  promote_resource_attributes: ["k8s.cluster.name", " k8s.job.name ", "k8s.namespace.name"]