feat(open-telemetry#5408): use stdout as default output

Signed-off-by: thomasgouveia <[email protected]>

Author: thomasgouveia

exporters/otlp/otlplog/otlplogfile/config.go

@@ -3,52 +3,71 @@
 
 package otlplogfile // import "go.opentelemetry.io/otel/exporters/otlp/otlplog/otlplogfile"
 
-import "time"
+import (
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"time"
+)
 
-type fnOpt func(config) config
-
-func (f fnOpt) applyOption(c config) config { return f(c) }
-
-// Option sets the configuration value for an Exporter.
-type Option interface {
-	applyOption(config) config
-}
+// Option configures a field of the configuration or return an error if needed.
+type Option func(*config) (*config, error)
 
 // config contains options for the OTLP Log file exporter.
 type config struct {
-	// Path to a file on disk where records must be appended.
-	// This file is preferably a json line file as stated in the specification.
-	// See: https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/file-exporter.md#json-lines-file
-	// See: https://jsonlines.org
-	path string
+	// Out is the output where the records should be written.
+	out io.WriteCloser
 	// Duration represents the interval when the buffer should be flushed.
 	flushInterval time.Duration
 }
 
-func newConfig(options []Option) config {
-	c := config{
-		path:          "/var/log/opentelemetry/logs.jsonl",
+func newConfig(options []Option) (*config, error) {
+	c := &config{
+		out:           os.Stdout,
 		flushInterval: 5 * time.Second,
 	}
+
+	var configErr error
 	for _, opt := range options {
-		c = opt.applyOption(c)
+		if _, err := opt(c); err != nil {
+			configErr = errors.Join(configErr, err)
+		}
 	}
-	return c
+
+	if configErr != nil {
+		return nil, configErr
+	}
+
+	return c, nil
 }
 
-// WithFlushInterval configures the duration after which the buffer is periodically flushed to the disk.
-func WithFlushInterval(flushInterval time.Duration) Option {
-	return fnOpt(func(c config) config {
-		c.flushInterval = flushInterval
-		return c
-	})
+// WithFile configures a file where the records will be exported.
+// An error is returned if the file could not be created or opened.
+func WithFile(path string) Option {
+	return func(c *config) (*config, error) {
+		file, err := os.OpenFile(path, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0o644)
+		if err != nil {
+			return nil, fmt.Errorf("failed to open file: %w", err)
+		}
+
+		return WithWriter(file)(c)
+	}
+}
+
+// WithWriter configures the destination where the exporter should output
+// the records. By default, if not specified, stdout is used.
+func WithWriter(w io.WriteCloser) Option {
+	return func(c *config) (*config, error) {
+		c.out = w
+		return c, nil
+	}
 }
 
-// WithPath defines a path to a file where the log records will be written.
-// If not set, will default to /var/log/opentelemetry/logs.jsonl.
-func WithPath(path string) Option {
-	return fnOpt(func(c config) config {
-		c.path = path
-		return c
-	})
+// WithFlushInterval configures the duration after which the buffer is periodically flushed to the output.
+func WithFlushInterval(flushInterval time.Duration) Option {
+	return func(c *config) (*config, error) {
+		c.flushInterval = flushInterval
+		return c, nil
+	}
 }

exporters/otlp/otlplog/otlplogfile/example_test.go

@@ -15,7 +15,7 @@ import (
 func Example() {
 	ctx := context.Background()
 	exp, err := otlplogfile.New(
-		otlplogfile.WithPath("/tmp/otlp-logs.jsonl"),
+		otlplogfile.WithFile("/tmp/otlp-logs.jsonl"),
 		otlplogfile.WithFlushInterval(time.Second),
 	)
 	if err != nil {

exporters/otlp/otlplog/otlplogfile/exporter.go

@@ -20,7 +20,7 @@ import (
 // defined here: https://github.com/open-telemetry/opentelemetry-specification/blob/v1.36.0/specification/protocol/file-exporter.md
 type Exporter struct {
 	mu      sync.Mutex
-	fw      *writer.FileWriter
+	w       *writer.Writer
 	stopped bool
 }
 
@@ -29,15 +29,18 @@ var _ log.Exporter = &Exporter{}
 
 // New returns a new [Exporter].
 func New(options ...Option) (*Exporter, error) {
-	cfg := newConfig(options)
+	cfg, err := newConfig(options)
+	if err != nil {
+		return nil, err
+	}
 
-	fw, err := writer.NewFileWriter(cfg.path, cfg.flushInterval)
+	w, err := writer.New(cfg.out, cfg.flushInterval)
 	if err != nil {
 		return nil, err
 	}
 
 	return &Exporter{
-		fw:      fw,
+		w:       w,
 		stopped: false,
 	}, nil
 }
@@ -65,7 +68,7 @@ func (e *Exporter) Export(ctx context.Context, records []log.Record) error {
 		return err
 	}
 
-	return e.fw.Export(by)
+	return e.w.Export(by)
 }
 
 // ForceFlush flushes data to the file.
@@ -77,7 +80,7 @@ func (e *Exporter) ForceFlush(_ context.Context) error {
 		return nil
 	}
 
-	return e.fw.Flush()
+	return e.w.Flush()
 }
 
 // Shutdown shuts down the exporter. Buffered data is written to disk,
@@ -91,5 +94,5 @@ func (e *Exporter) Shutdown(_ context.Context) error {
 	}
 
 	e.stopped = true
-	return e.fw.Shutdown()
+	return e.w.Shutdown()
 }

exporters/otlp/otlplog/otlplogfile/exporter_test.go

@@ -23,13 +23,13 @@ import (
 
 // tempFile creates a temporary file for the given test case and returns its path on disk.
 // The file is automatically cleaned up when the test ends.
-func tempFile(tb testing.TB) string {
+func tempFile(tb testing.TB) *os.File {
 	f, err := os.CreateTemp(tb.TempDir(), tb.Name())
 	assert.NoError(tb, err, "must not error when creating temporary file")
 	tb.Cleanup(func() {
 		assert.NoError(tb, os.RemoveAll(path.Dir(f.Name())), "must clean up files after being written")
 	})
-	return f.Name()
+	return f
 }
 
 // makeRecords is a helper function to generate an array of log record with the desired size.
@@ -48,10 +48,10 @@ func makeRecords(count int, message string) []sdklog.Record {
 }
 
 func TestExporter(t *testing.T) {
-	filepath := tempFile(t)
+	file := tempFile(t)
 	records := makeRecords(1, "hello, world!")
 
-	exporter, err := New(WithPath(filepath))
+	exporter, err := New(WithWriter(file))
 	assert.NoError(t, err)
 	t.Cleanup(func() {
 		assert.NoError(t, exporter.Shutdown(context.TODO()))
@@ -64,8 +64,8 @@ func TestExporter(t *testing.T) {
 }
 
 func TestExporterConcurrentSafe(t *testing.T) {
-	filepath := tempFile(t)
-	exporter, err := New(WithPath(filepath))
+	file := tempFile(t)
+	exporter, err := New(WithWriter(file))
 	require.NoError(t, err, "New()")
 
 	const goroutines = 10

exporters/otlp/otlplog/otlplogfile/internal/writer/writer.go

@@ -4,38 +4,29 @@
 package writer // import "go.opentelemetry.io/otel/exporters/otlp/otlplog/otlplogfile/internal/writer"
 
 import (
-	"fmt"
 	"io"
-	"os"
 	"sync"
 	"time"
 )
 
-// FileWriter writes data to a configured file.
+// Writer writes data to the configured io.WriteCloser.
 // It is buffered to reduce I/O operations to improve performance.
-type FileWriter struct {
-	path string
-	file io.WriteCloser
-	mu   sync.Mutex
+type Writer struct {
+	out io.WriteCloser
+	mu  sync.Mutex
 
 	flushInterval time.Duration
 	flushTicker   *time.Ticker
 	stopTicker    chan struct{}
 }
 
-var _ flusher = (*FileWriter)(nil)
+var _ flusher = (*Writer)(nil)
 
-// NewFileWriter initializes a file writer for the file at the given path.
-func NewFileWriter(path string, flushInterval time.Duration) (*FileWriter, error) {
-	file, err := os.OpenFile(path, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0o644)
-	if err != nil {
-		return nil, fmt.Errorf("failed to open file: %w", err)
-	}
-
-	fw := &FileWriter{
-		path:          path,
+// New initializes a writer for the given io.WriteCloser.
+func New(w io.WriteCloser, flushInterval time.Duration) (*Writer, error) {
+	fw := &Writer{
 		flushInterval: flushInterval,
-		file:          newBufferedWriteCloser(file),
+		out:           newBufferedWriteCloser(w),
 	}
 
 	if fw.flushInterval > 0 {
@@ -46,37 +37,37 @@ func NewFileWriter(path string, flushInterval time.Duration) (*FileWriter, error
 }
 
 // Export writes the given data in the file.
-func (w *FileWriter) Export(data []byte) error {
+func (w *Writer) Export(data []byte) error {
 	w.mu.Lock()
 	defer w.mu.Unlock()
 
-	if _, err := w.file.Write(data); err != nil {
+	if _, err := w.out.Write(data); err != nil {
 		return err
 	}
 
 	// As stated in the specification, line separator is \n.
-	// https://github.com/open-telemetry/opentelemetry-specification/blob/v1.36.0/specification/protocol/file-exporter.md#json-lines-file
-	if _, err := io.WriteString(w.file, "\n"); err != nil {
+	// https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/file-exporter.md#json-lines-file
+	if _, err := io.WriteString(w.out, "\n"); err != nil {
 		return err
 	}
 
 	return nil
 }
 
 // Shutdown stops the flusher. It also stops the flush ticker if set.
-func (w *FileWriter) Shutdown() error {
+func (w *Writer) Shutdown() error {
 	w.mu.Lock()
 	defer w.mu.Unlock()
 
 	if w.flushTicker != nil {
 		close(w.stopTicker)
 	}
-	return w.file.Close()
+	return w.out.Close()
 }
 
 // Flush writes buffered data to disk.
-func (w *FileWriter) Flush() error {
-	ff, ok := w.file.(flusher)
+func (w *Writer) Flush() error {
+	ff, ok := w.out.(flusher)
 	if !ok {
 		return nil
 	}
@@ -88,11 +79,11 @@ func (w *FileWriter) Flush() error {
 }
 
 // startFlusher starts the flusher to periodically flush the buffer.
-func (w *FileWriter) startFlusher() {
+func (w *Writer) startFlusher() {
 	w.mu.Lock()
 	defer w.mu.Unlock()
 
-	ff, ok := w.file.(flusher)
+	ff, ok := w.out.(flusher)
 	if !ok {
 		return
 	}

exporters/otlp/otlplog/otlplogfile/internal/writer/writer_test.go

@@ -31,12 +31,11 @@ func tempFile(tb testing.TB) *os.File {
 func TestNewFileWriter(t *testing.T) {
 	f := tempFile(t)
 
-	writer, err := NewFileWriter(f.Name(), 0)
+	writer, err := New(f, 0)
 	// nolint: errcheck
 	defer writer.Shutdown()
 
 	assert.NoError(t, err, "must not error when creating the file writer")
-	assert.Equal(t, f.Name(), writer.path, "writer file path must be the same than the file path")
 
 	// Ensure file was created
 	_, err = os.Stat(f.Name())
@@ -46,7 +45,7 @@ func TestNewFileWriter(t *testing.T) {
 func TestFileWriterExport(t *testing.T) {
 	f := tempFile(t)
 
-	writer, err := NewFileWriter(f.Name(), 0)
+	writer, err := New(f, 0)
 	// nolint: errcheck
 	defer writer.Shutdown()
 	require.NoError(t, err, "must not error when creating the file writer")
@@ -66,15 +65,15 @@ func TestFileWriterExport(t *testing.T) {
 func TestFileWriterShutdown(t *testing.T) {
 	f := tempFile(t)
 
-	writer, err := NewFileWriter(f.Name(), 0)
+	writer, err := New(f, 0)
 	require.NoError(t, err, "must not error when creating the file writer")
 	assert.NoError(t, writer.Shutdown(), "must not error when calling Shutdown()")
 }
 
 func TestFileWriterConcurrentSafe(t *testing.T) {
 	f := tempFile(t)
 
-	writer, err := NewFileWriter(f.Name(), 0)
+	writer, err := New(f, 0)
 	require.NoError(t, err, "must not error when creating the file writer")
 
 	const goroutines = 10