feat(open-telemetry#5408): add otlplogfile exporter

This commit adds a new experimental exporter `otlplogfile`, that outputs log records to a JSON line file.
It is based on the following specification: https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/file-exporter.md

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

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

@@ -8,8 +8,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"os"
-	"path"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -18,9 +16,9 @@ import (
 const (
 	msg = "hello, world!"
 
-	SizeByte     = 1
-	SizeKiloByte = 1 << (10 * iota)
-	SizeMegaByte
+	sizeByte     = 1
+	sizeKiloByte = 1 << (10 * iota)
+	sizeMegaByte
 )
 
 type noopWriteCloser struct {
@@ -44,32 +42,21 @@ func TestBufferedWrites(t *testing.T) {
 
 var errBenchmark error
 
-func BenchmarkWriter(b *testing.B) {
-	tempfile := func(tb testing.TB) io.WriteCloser {
-		f, err := os.CreateTemp(tb.TempDir(), tb.Name())
-		assert.NoError(tb, err, "must not error when creating benchmark temp file")
-		tb.Cleanup(func() {
-			assert.NoError(tb, os.RemoveAll(path.Dir(f.Name())), "must clean up files after being written")
-		})
-		return f
-	}
-
+func BenchmarkBufferedWriter(b *testing.B) {
 	for _, payloadSize := range []int{
-		10 * SizeKiloByte,
-		100 * SizeKiloByte,
-		SizeMegaByte,
-		10 * SizeMegaByte,
+		10 * sizeKiloByte,
+		100 * sizeKiloByte,
+		sizeMegaByte,
+		10 * sizeMegaByte,
 	} {
 		payload := make([]byte, payloadSize)
 		for i := 0; i < payloadSize; i++ {
 			payload[i] = 'a'
 		}
 
 		for name, w := range map[string]io.WriteCloser{
-			"discard":          &noopWriteCloser{io.Discard},
-			"buffered-discard": newBufferedWriteCloser(&noopWriteCloser{io.Discard}),
-			"raw-file":         tempfile(b),
-			"buffered-file":    newBufferedWriteCloser(tempfile(b)),
+			"raw-file":      tempFile(b),
+			"buffered-file": newBufferedWriteCloser(tempFile(b)),
 		} {
 			w := w
 			b.Run(fmt.Sprintf("%s_%d_bytes", name, payloadSize), func(b *testing.B) {

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

@@ -4,69 +4,62 @@
 package writer
 
 import (
-	"fmt"
 	"os"
 	"path"
 	"testing"
-	"time"
 
 	"github.com/stretchr/testify/assert"
-)
-
-const (
-	jsonLine string = "{\"resourceLogs\":[{\"resource\":{\"attributes\":[{\"key\":\"resource-attr\",\"value\":{\"stringValue\":\"resource-attr-val-1\"}}]},\"scopeLogs\":[{\"scope\":{},\"logRecords\":[{\"timeUnixNano\":\"1581452773000000789\",\"severityNumber\":9,\"severityText\":\"Info\",\"body\":{\"stringValue\":\"This is a log message\"},\"attributes\":[{\"key\":\"app\",\"value\":{\"stringValue\":\"server\"}},{\"key\":\"instance_num\",\"value\":{\"intValue\":\"1\"}}],\"droppedAttributesCount\":1,\"traceId\":\"08040201000000000000000000000000\",\"spanId\":\"0102040800000000\"},{\"timeUnixNano\":\"1581452773000000789\",\"severityNumber\":9,\"severityText\":\"Info\",\"body\":{\"stringValue\":\"something happened\"},\"attributes\":[{\"key\":\"customer\",\"value\":{\"stringValue\":\"acme\"}},{\"key\":\"env\",\"value\":{\"stringValue\":\"dev\"}}],\"droppedAttributesCount\":1,\"traceId\":\"\",\"spanId\":\"\"}]}]}]}"
+	"github.com/stretchr/testify/require"
 )
 
 // 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")
+	require.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
+}
+
+func TestNewFileWriter(t *testing.T) {
+	f := tempFile(t)
+
+	writer, err := NewFileWriter(f.Name(), 0)
+	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())
+	assert.NoError(t, err, "must not error when trying to retrieve file stats")
 }
 
-func BenchmarkFileWriter(b *testing.B) {
-	for _, logLines := range []int{
-		10,
-		100,
-		1000,
-		5000,
-	} {
-		logs := make([]string, logLines)
-		for i := 0; i < logLines; i++ {
-			logs = append(logs, jsonLine)
-		}
+func TestFileWriterExport(t *testing.T) {
+	f := tempFile(t)
+
+	writer, err := NewFileWriter(f.Name(), 0)
+	defer writer.Shutdown()
+	require.NoError(t, err, "must not error when creating the file writer")
 
-		for name, interval := range map[string]time.Duration{
-			"no-flush":    0,
-			"flush-10ms":  10 * time.Millisecond,
-			"flush-100ms": 100 * time.Millisecond,
-			"flush-1s":    time.Second,
-			"flush-10s":   10 * time.Second,
-		} {
-			file := tempFile(b)
-			fw, err := NewFileWriter(file, interval)
-			assert.NoError(b, err, "must not error when creating FileWriter")
+	data := []byte("helloworld")
+	assert.NoError(t, writer.Export(data))
 
-			b.Run(fmt.Sprintf("%s_%d_logs", name, logLines), func(b *testing.B) {
-				b.ReportAllocs()
-				b.ResetTimer()
+	// Force data to be written to disk.
+	writer.Flush()
+
+	// Read file and verify content
+	content, err := os.ReadFile(f.Name())
+	require.NoError(t, err, "must not error when reading file content")
+	assert.Equal(t, "helloworld\n", string(content))
+}
 
-				for i := 0; i < b.N; i++ {
-					for _, logLine := range logs {
-						if err := fw.Export([]byte(logLine)); err != nil {
-							b.Fatalf("failed to write data: %v", err)
-						}
-					}
-				}
-			})
+func TestFileWriterShutdown(t *testing.T) {
+	f := tempFile(t)
 
-			if err := fw.Shutdown(); err != nil {
-				b.Fatalf("failed to shutdown FileWriter: %v", err)
-			}
-		}
-	}
+	writer, err := NewFileWriter(f.Name(), 0)
+	require.NoError(t, err, "must not error when creating the file writer")
+	assert.NoError(t, writer.Shutdown(), "must not error when calling Shutdown()")
 }