[otelcol] Allow confmap to write logs using configured logger

otelcol/collector.go

@@ -15,6 +15,7 @@ import (
 
 	"go.uber.org/multierr"
 	"go.uber.org/zap"
+	"go.uber.org/zap/zaptest/observer"
 
 	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/confmap"
@@ -109,14 +110,17 @@ type Collector struct {
 	signalsChannel chan os.Signal
 	// asyncErrorChannel is used to signal a fatal error from any component.
 	asyncErrorChannel chan error
+
+	ol *observer.ObservedLogs
 }
 
 // NewCollector creates and returns a new instance of Collector.
 func NewCollector(set CollectorSettings) (*Collector, error) {
 	var err error
 	configProvider := set.ConfigProvider
 
-	set.ConfigProviderSettings.ResolverSettings.ProviderSettings = confmap.ProviderSettings{Logger: zap.NewNop()}
+	core, ol := observer.New(zap.DebugLevel)
+	set.ConfigProviderSettings.ResolverSettings.ProviderSettings = confmap.ProviderSettings{Logger: zap.New(core)}
 	set.ConfigProviderSettings.ResolverSettings.ConverterSettings = confmap.ConverterSettings{}
 
 	if configProvider == nil {
@@ -137,6 +141,7 @@ func NewCollector(set CollectorSettings) (*Collector, error) {
 		signalsChannel:    make(chan os.Signal, 3),
 		asyncErrorChannel: make(chan error),
 		configProvider:    configProvider,
+		ol:                ol,
 	}, nil
 }
 
@@ -202,6 +207,12 @@ func (col *Collector) setupConfigurationComponents(ctx context.Context) error {
 		return err
 	}
 
+	if col.ol != nil {
+		for _, log := range col.ol.All() {
+			col.service.Logger().Log(log.Level, log.Message)
+		}
+	}
+
 	if !col.set.SkipSettingGRPCLogger {
 		grpclog.SetLogger(col.service.Logger(), cfg.Service.Telemetry.Logs.Level)
 	}

otelcol/collector_test.go

@@ -15,6 +15,7 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"go.uber.org/zap"
 
 	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/confmap"
@@ -476,6 +477,61 @@ func TestPassConfmapToServiceFailure(t *testing.T) {
 	require.Error(t, err)
 }
 
+type provider struct {
+	logger *zap.Logger
+}
+
+func newWithSettings(ps confmap.ProviderSettings) confmap.Provider {
+	return &provider{
+		logger: ps.Logger,
+	}
+}
+
+func newFactory() confmap.ProviderFactory {
+	return confmap.NewProviderFactory(newWithSettings)
+}
+
+func (p *provider) Retrieve(_ context.Context, uri string, _ confmap.WatcherFunc) (*confmap.Retrieved, error) {
+	p.logger.Info("this is a test log")
+	return confmap.NewRetrieved("test")
+}
+
+func (*provider) Scheme() string {
+	return "test"
+}
+
+func (*provider) Shutdown(context.Context) error {
+	return nil
+}
+
+func TestCollectorConfmapLogs(t *testing.T) {
+	configProviderSettings := newDefaultConfigProviderSettings([]string{filepath.Join("testdata", "otelcol-confmap-logging.yaml")})
+	configProviderSettings.ResolverSettings.ProviderFactories = append(configProviderSettings.ResolverSettings.ProviderFactories, newFactory())
+
+	set := CollectorSettings{
+		BuildInfo:              component.NewDefaultBuildInfo(),
+		Factories:              nopFactories,
+		ConfigProviderSettings: configProviderSettings,
+	}
+	col, err := NewCollector(set)
+	require.NoError(t, err)
+
+	wg := startCollector(context.Background(), t, col)
+
+	col.Shutdown()
+	wg.Wait()
+	assert.Equal(t, StateClosed, col.GetState())
+
+	require.NotNil(t, col.ol)
+	require.Greater(t, col.ol.Len(), 0)
+
+	messages := make([]string, 0, col.ol.Len())
+	for _, l := range col.ol.All() {
+		messages = append(messages, l.Message)
+	}
+	assert.Contains(t, messages, "this is a test log")
+}
+
 func startCollector(ctx context.Context, t *testing.T, col *Collector) *sync.WaitGroup {
 	wg := &sync.WaitGroup{}
 	wg.Add(1)

otelcol/testdata/otelcol-confmap-logging.yaml

@@ -0,0 +1,34 @@
+receivers:
+  nop:
+
+processors:
+  nop:
+
+exporters:
+  nop:
+
+extensions:
+  nop:
+
+connectors:
+  nop/con:
+
+service:
+  telemetry:
+    logs:
+      initial_fields:
+        "test": ${test:ANYTHING}
+  extensions: [nop]
+  pipelines:
+    traces:
+      receivers: [nop]
+      processors: [nop]
+      exporters: [nop, nop/con]
+    metrics:
+      receivers: [nop]
+      processors: [nop]
+      exporters: [nop]
+    logs:
+      receivers: [nop, nop/con]
+      processors: [nop]
+      exporters: [nop]