[exporter/file] add encoding extension support

.chloggen/encoding_fileexporter.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: fileexporter
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Adopt the encoding extension with the file exporter.
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [31774]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

exporter/fileexporter/README.md

@@ -47,6 +47,7 @@ The following settings are optional:
   - localtime : [default: false (use UTC)] whether or not the timestamps in backup files is formatted according to the host's local time.
 
 - `format`[default: json]: define the data format of encoded telemetry data. The setting can be overridden with `proto`.
+- `encoding`[default: none]: if specified, uses an encoding extension to encode telemetry data. Overrides `format`.
 - `append`[default: `false`] defines whether append to the file (`true`) or truncate (`false`). If `append: true` is set then setting `rotation` or `compression` is currently not supported.
 - `compression`[no default]: the compression algorithm used when exporting telemetry data to file. Supported compression algorithms:`zstd`
 - `flush_interval`[default: 1s]: `time.Duration` interval between flushes. See [time.ParseDuration](https://pkg.go.dev/time#ParseDuration) for valid formats. 

exporter/fileexporter/config.go

@@ -40,6 +40,10 @@ type Config struct {
 	// - proto:  OTLP binary protobuf bytes.
 	FormatType string `mapstructure:"format"`
 
+	// Encoding defines the encoding of the telemetry data.
+	// If specified, it overrides `FormatType` and applies an encoding extension.
+	Encoding *component.ID `mapstructure:"encoding"`
+
 	// Compression Codec used to export telemetry data
 	// Supported compression algorithms:`zstd`
 	Compression string `mapstructure:"compression"`

exporter/fileexporter/encoding_test.go

@@ -0,0 +1,120 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package fileexporter
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+	"go.opentelemetry.io/collector/component"
+	"go.opentelemetry.io/collector/component/componenttest"
+	"go.opentelemetry.io/collector/exporter/exportertest"
+	"go.opentelemetry.io/collector/extension/extensiontest"
+	"go.opentelemetry.io/collector/pdata/pcommon"
+	"go.opentelemetry.io/collector/pdata/plog"
+	"go.opentelemetry.io/collector/pdata/pmetric"
+	"go.opentelemetry.io/collector/pdata/ptrace"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/extension/encoding/otlpencodingextension"
+)
+
+type hostWithEncoding struct {
+	encodings map[component.ID]component.Component
+}
+
+func (h hostWithEncoding) GetFactory(kind component.Kind, componentType component.Type) component.Factory {
+	panic("unsupported")
+}
+
+func (h hostWithEncoding) GetExtensions() map[component.ID]component.Component {
+	return h.encodings
+}
+
+func (h hostWithEncoding) GetExporters() map[component.DataType]map[component.ID]component.Component {
+	panic("unsupported")
+}
+
+func TestEncoding(t *testing.T) {
+	f := NewFactory()
+	cfg := f.CreateDefaultConfig().(*Config)
+	cfg.Path = filepath.Join(t.TempDir(), "encoding.txt")
+	id := component.MustNewID("otlpjson")
+	cfg.Encoding = &id
+
+	ef := otlpencodingextension.NewFactory()
+	efCfg := ef.CreateDefaultConfig().(*otlpencodingextension.Config)
+	efCfg.Protocol = "otlp_json"
+	ext, err := ef.CreateExtension(context.Background(), extensiontest.NewNopCreateSettings(), efCfg)
+	require.NoError(t, err)
+	require.NoError(t, ext.Start(context.Background(), componenttest.NewNopHost()))
+
+	me, err := f.CreateMetricsExporter(context.Background(), exportertest.NewNopCreateSettings(), cfg)
+	require.NoError(t, err)
+	te, err := f.CreateTracesExporter(context.Background(), exportertest.NewNopCreateSettings(), cfg)
+	require.NoError(t, err)
+	le, err := f.CreateLogsExporter(context.Background(), exportertest.NewNopCreateSettings(), cfg)
+	require.NoError(t, err)
+	host := hostWithEncoding{
+		map[component.ID]component.Component{id: ext},
+	}
+	require.NoError(t, me.Start(context.Background(), host))
+	require.NoError(t, te.Start(context.Background(), host))
+	require.NoError(t, le.Start(context.Background(), host))
+	t.Cleanup(func() {
+
+	})
+
+	require.NoError(t, me.ConsumeMetrics(context.Background(), generateMetrics()))
+	require.NoError(t, te.ConsumeTraces(context.Background(), generateTraces()))
+	require.NoError(t, le.ConsumeLogs(context.Background(), generateLogs()))
+
+	require.NoError(t, me.Shutdown(context.Background()))
+	require.NoError(t, te.Shutdown(context.Background()))
+	require.NoError(t, le.Shutdown(context.Background()))
+
+	b, err := os.ReadFile(cfg.Path)
+	require.NoError(t, err)
+	require.Contains(t, string(b), `{"resourceMetrics":`)
+	require.Contains(t, string(b), `{"resourceSpans":`)
+	require.Contains(t, string(b), `{"resourceLogs":`)
+}
+
+func generateLogs() plog.Logs {
+	logs := plog.NewLogs()
+	rl := logs.ResourceLogs().AppendEmpty()
+	rl.Resource().Attributes().PutStr("resource", "R1")
+	l := rl.ScopeLogs().AppendEmpty().LogRecords().AppendEmpty()
+	l.Body().SetStr("test log message")
+	l.SetTimestamp(pcommon.NewTimestampFromTime(time.Now()))
+	return logs
+}
+
+func generateMetrics() pmetric.Metrics {
+	metrics := pmetric.NewMetrics()
+	rm := metrics.ResourceMetrics().AppendEmpty()
+	rm.Resource().Attributes().PutStr("resource", "R1")
+	m := rm.ScopeMetrics().AppendEmpty().Metrics().AppendEmpty()
+	m.SetName("test_metric")
+	dp := m.SetEmptyGauge().DataPoints().AppendEmpty()
+	dp.Attributes().PutStr("test_attr", "value_1")
+	dp.SetIntValue(123)
+	dp.SetTimestamp(pcommon.NewTimestampFromTime(time.Now()))
+	return metrics
+}
+
+func generateTraces() ptrace.Traces {
+	traces := ptrace.NewTraces()
+	rs := traces.ResourceSpans().AppendEmpty()
+	rs.Resource().Attributes().PutStr("resource", "R1")
+	span := rs.ScopeSpans().AppendEmpty().Spans().AppendEmpty()
+	span.Attributes().PutStr("test_attr", "value_1")
+	span.SetName("test_span")
+	span.SetStartTimestamp(pcommon.NewTimestampFromTime(time.Now().Add(-1 * time.Second)))
+	span.SetEndTimestamp(pcommon.NewTimestampFromTime(time.Now()))
+	return traces
+}

exporter/fileexporter/file_exporter.go

@@ -44,11 +44,14 @@ func (e *fileExporter) consumeLogs(_ context.Context, ld plog.Logs) error {
 }
 
 // Start starts the flush timer if set.
-func (e *fileExporter) Start(_ context.Context, _ component.Host) error {
-	e.marshaller = newMarshaller(e.conf)
+func (e *fileExporter) Start(_ context.Context, host component.Host) error {
+	var err error
+	e.marshaller, err = newMarshaller(e.conf, host)
+	if err != nil {
+		return err
+	}
 	export := buildExportFunc(e.conf)
 
-	var err error
 	e.writer, err = newFileWriter(e.conf.Path, e.conf.Append, e.conf.Rotation, e.conf.FlushInterval, export)
 	if err != nil {
 		return err

exporter/fileexporter/go.mod

@@ -5,6 +5,7 @@ go 1.21
 require (
 	github.com/hashicorp/golang-lru/v2 v2.0.7
 	github.com/klauspost/compress v1.17.7
+	github.com/open-telemetry/opentelemetry-collector-contrib/extension/encoding/otlpencodingextension v0.96.0
 	github.com/open-telemetry/opentelemetry-collector-contrib/internal/coreinternal v0.96.0
 	github.com/open-telemetry/opentelemetry-collector-contrib/internal/sharedcomponent v0.96.0
 	github.com/stretchr/testify v1.9.0
@@ -24,7 +25,7 @@ require (
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/cenkalti/backoff/v4 v4.2.1 // indirect
 	github.com/cespare/xxhash/v2 v2.2.0 // indirect
-	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
 	github.com/go-logr/logr v1.4.1 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/go-viper/mapstructure/v2 v2.0.0-alpha.1 // indirect
@@ -38,7 +39,8 @@ require (
 	github.com/mitchellh/reflectwalk v1.0.2 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.2 // indirect
-	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/open-telemetry/opentelemetry-collector-contrib/extension/encoding v0.96.0 // indirect
+	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/prometheus/client_golang v1.19.0 // indirect
 	github.com/prometheus/client_model v0.6.0 // indirect
 	github.com/prometheus/common v0.48.0 // indirect
@@ -77,3 +79,5 @@ replace github.com/open-telemetry/opentelemetry-collector-contrib/pkg/pdatautil
 replace github.com/open-telemetry/opentelemetry-collector-contrib/pkg/pdatatest => ../../pkg/pdatatest
 
 replace github.com/open-telemetry/opentelemetry-collector-contrib/pkg/golden => ../../pkg/golden
+
+replace github.com/open-telemetry/opentelemetry-collector-contrib/extension/encoding/otlpencodingextension => ../../extension/encoding/otlpencodingextension

exporter/fileexporter/grouping_file_exporter.go

@@ -244,8 +244,12 @@ func group[T any](e *groupingFileExporter, groups map[string][]T, resource pcomm
 }
 
 // Start initializes and starts the exporter.
-func (e *groupingFileExporter) Start(context.Context, component.Host) error {
-	e.marshaller = newMarshaller(e.conf)
+func (e *groupingFileExporter) Start(_ context.Context, host component.Host) error {
+	var err error
+	e.marshaller, err = newMarshaller(e.conf, host)
+	if err != nil {
+		return err
+	}
 	export := buildExportFunc(e.conf)
 
 	pathParts := strings.Split(e.conf.Path, "*")

exporter/fileexporter/marshaller.go

@@ -4,6 +4,10 @@
 package fileexporter // import "github.com/open-telemetry/opentelemetry-collector-contrib/exporter/fileexporter"
 
 import (
+	"errors"
+	"fmt"
+
+	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/pdata/plog"
 	"go.opentelemetry.io/collector/pdata/pmetric"
 	"go.opentelemetry.io/collector/pdata/ptrace"
@@ -34,18 +38,38 @@ type marshaller struct {
 	formatType string
 }
 
-func newMarshaller(conf *Config) *marshaller {
+func newMarshaller(conf *Config, host component.Host) (*marshaller, error) {
+	if conf.Encoding != nil {
+		encoding := host.GetExtensions()[*conf.Encoding]
+		if encoding == nil {
+			return nil, fmt.Errorf("unknown encoding %q", conf.Encoding)
+		}
+		// cast with ok to avoid panics.
+		tm, _ := encoding.(ptrace.Marshaler)
+		pm, _ := encoding.(pmetric.Marshaler)
+		lm, _ := encoding.(plog.Marshaler)
+		return &marshaller{
+			tracesMarshaler:  tm,
+			metricsMarshaler: pm,
+			logsMarshaler:    lm,
+			compression:      conf.Compression,
+			compressor:       buildCompressor(conf.Compression),
+		}, nil
+	}
 	return &marshaller{
 		formatType:       conf.FormatType,
 		tracesMarshaler:  tracesMarshalers[conf.FormatType],
 		metricsMarshaler: metricsMarshalers[conf.FormatType],
 		logsMarshaler:    logsMarshalers[conf.FormatType],
 		compression:      conf.Compression,
 		compressor:       buildCompressor(conf.Compression),
-	}
+	}, nil
 }
 
 func (m *marshaller) marshalTraces(td ptrace.Traces) ([]byte, error) {
+	if m.metricsMarshaler == nil {
+		return nil, errors.New("traces are not supported by encoding")
+	}
 	buf, err := m.tracesMarshaler.MarshalTraces(td)
 	if err != nil {
 		return nil, err
@@ -55,6 +79,9 @@ func (m *marshaller) marshalTraces(td ptrace.Traces) ([]byte, error) {
 }
 
 func (m *marshaller) marshalMetrics(md pmetric.Metrics) ([]byte, error) {
+	if m.metricsMarshaler == nil {
+		return nil, errors.New("metrics are not supported by encoding")
+	}
 	buf, err := m.metricsMarshaler.MarshalMetrics(md)
 	if err != nil {
 		return nil, err
@@ -64,6 +91,9 @@ func (m *marshaller) marshalMetrics(md pmetric.Metrics) ([]byte, error) {
 }
 
 func (m *marshaller) marshalLogs(ld plog.Logs) ([]byte, error) {
+	if m.metricsMarshaler == nil {
+		return nil, errors.New("logs are not supported by encoding")
+	}
 	buf, err := m.logsMarshaler.MarshalLogs(ld)
 	if err != nil {
 		return nil, err