Add configuration validation

Makefile

@@ -72,4 +72,4 @@ fmt:
 .PHONY: tidy
 tidy:
 	rm -fr go.sum
-	$(GOCMD) mod tidy -compat=1.22.0
+	$(GOCMD) mod tidy -compat=1.24.0

go.mod

@@ -10,6 +10,7 @@ require (
 	go.opentelemetry.io/collector/component v1.49.0
 	go.opentelemetry.io/collector/component/componenttest v0.143.0
 	go.opentelemetry.io/collector/confmap v1.49.0
+	go.opentelemetry.io/collector/confmap/xconfmap v0.143.0
 	go.opentelemetry.io/collector/consumer v1.49.0
 	go.opentelemetry.io/collector/consumer/xconsumer v0.143.0
 	go.opentelemetry.io/collector/pdata v1.49.0

internal/config.go

@@ -26,6 +26,7 @@ import (
 	"github.com/go-viper/mapstructure/v2"
 	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/confmap"
+	"go.opentelemetry.io/collector/confmap/xconfmap"
 	"gopkg.in/yaml.v3"
 )
 
@@ -63,13 +64,8 @@ func parseConfig[C any](id component.ID, yamlConfig string, createDefaultConfig
 		return parseMultipleConfigs[C](yamlConfig, deserializedConf, createDefaultConfig)
 	}
 
-	configMap := make(map[string]any)
-	for k, v := range deserializedConf.ToStringMap() {
-		configMap[k] = escapeDollarSigns(v)
-	}
-
 	defaultConfig := createDefaultConfig()
-	err = confmap.NewFromStringMap(configMap).Unmarshal(&defaultConfig)
+	err = unmarshalValidConfig(deserializedConf, defaultConfig)
 	if err != nil {
 		return nil, err
 	}
@@ -89,13 +85,8 @@ func parseMultipleConfigs[C any](yamlConfig string, deserializedConf *confmap.Co
 			return nil, err
 		}
 
-		subConfigMap := map[string]any{}
-		for k, v := range sub.ToStringMap() {
-			subConfigMap[k] = escapeDollarSigns(v)
-		}
-
 		defaultConfig := createDefaultConfig()
-		err = confmap.NewFromStringMap(subConfigMap).Unmarshal(&defaultConfig)
+		err = unmarshalValidConfig(sub, defaultConfig)
 		if err != nil {
 			return nil, err
 		}
@@ -106,6 +97,25 @@ func parseMultipleConfigs[C any](yamlConfig string, deserializedConf *confmap.Co
 	return configs, nil
 }
 
+func unmarshalValidConfig[C any](cfg *confmap.Conf, defaultConfig C) error {
+	subConfigMap := map[string]any{}
+	for k, v := range cfg.ToStringMap() {
+		subConfigMap[k] = escapeDollarSigns(v)
+	}
+
+	err := confmap.NewFromStringMap(subConfigMap).Unmarshal(&defaultConfig)
+	if err != nil {
+		return err
+	}
+
+	validator, ok := any(defaultConfig).(xconfmap.Validator)
+	if ok {
+		return validator.Validate()
+	}
+
+	return nil
+}
+
 func sortedConfigKeys(yamlData string) ([]string, error) {
 	var root yaml.Node
 	if err := yaml.Unmarshal([]byte(yamlData), &root); err != nil {

internal/config_test.go

@@ -20,6 +20,7 @@
 package internal
 
 import (
+	"errors"
 	"testing"
 
 	"github.com/open-telemetry/opentelemetry-collector-contrib/processor/transformprocessor"
@@ -52,6 +53,54 @@ func Test_parseConfig_singleConfig(t *testing.T) {
 	require.NotEmpty(t, pc.MetricStatements)
 }
 
+func Test_parseConfig_configValidator(t *testing.T) {
+	id := component.MustNewID("test")
+	tests := []struct {
+		name      string
+		config    string
+		expectErr bool
+	}{
+		{
+			name:      "valid single config",
+			config:    "valid: true",
+			expectErr: false,
+		},
+		{
+			name:      "invalid single config",
+			config:    "valid: false",
+			expectErr: true,
+		},
+		{
+			name:      "valid multiple config",
+			config:    "test:\n valid: true\ntest/b:\n valid: true",
+			expectErr: false,
+		},
+		{
+			name:      "invalid multiple config",
+			config:    "test:\n valid: true\ntest/b:\n valid: false",
+			expectErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			_, err := parseConfig[mockConfig](
+				id,
+				tt.config,
+				func() *mockConfig {
+					return &mockConfig{Valid: !tt.expectErr}
+				},
+			)
+
+			if tt.expectErr {
+				require.ErrorIs(t, err, errInvalidMockConfig)
+			} else {
+				require.NoError(t, err)
+			}
+		})
+	}
+}
+
 func Test_parseConfig_multipleConfig(t *testing.T) {
 	config := readTestData(t, configMultiple)
 	allConfigs, err := parseConfig[transformprocessor.Config](
@@ -87,3 +136,18 @@ func Test_parseConfig_invalidConfig(t *testing.T) {
 	)
 	require.ErrorContains(t, err, "cannot be used as a Conf")
 }
+
+var (
+	errInvalidMockConfig = errors.New("config validation failed")
+)
+
+type mockConfig struct {
+	Valid bool `mapstructure:"valid"`
+}
+
+func (m *mockConfig) Validate() error {
+	if m.Valid {
+		return nil
+	}
+	return errInvalidMockConfig
+}