[exporter/debug] format spans as one-liners in normal verbosity (op…

…en-telemetry#10280)

#### Description

This is an initial barebones implementation that only outputs the span's
name, trace ID and span ID. Other useful fields like duration etc. can
be added in follow-up enhancements.

This pull request is part of
open-telemetry#7806;
it implements the change for traces. The changes for
[logs](open-telemetry#10225)
and metrics will be proposed in separate pull requests.

This change applies to the Debug exporter only. The behavior of the
Logging exporter remains unchanged. To use this behavior, switch from
the deprecated Logging exporter to Debug exporter.

#### Link to tracking issue

- open-telemetry#7806

#### Testing

Added unit tests for the formatter.

#### Documentation

Described the formatting in the Debug exporter's README.

---------

Co-authored-by: Pablo Baeyens <pbaeyens31+github@gmail.com>

.chloggen/debug-exporter-normal-verbosity-traces.yaml

@@ -0,0 +1,25 @@
+# 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. otlpreceiver)
+component: exporter/debug
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: In `normal` verbosity, display one line of text for each span
+
+# One or more tracking issues or pull requests related to the change
+issues: [7806]
+
+# (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:
+
+# 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/debugexporter/README.md

@@ -63,21 +63,22 @@ Here's an example output:
 
 ### Normal verbosity
 
-With `verbosity: normal`, the exporter outputs about one line for each telemetry record, including its body and attributes.
+With `verbosity: normal`, the exporter outputs about one line for each telemetry record.
 The "one line per telemetry record" is not a strict rule.
 For example, logs with multiline body will be output as multiple lines.
 
 > [!IMPORTANT]
-> Currently the `normal` verbosity is only implemented for logs.
-> Metrics and traces are going to be implemented in the future.
-> The current behavior for metrics and traces is the same as in `basic` verbosity.
+> Currently the `normal` verbosity is only implemented for logs and traces.
+> Metrics are going to be implemented in the future.
+> The current behavior for metrics is the same as in `basic` verbosity.
 
 Here's an example output:
 
 ```console
-2024-05-27T12:46:22.423+0200    info    LogsExporter    {"kind": "exporter", "data_type": "logs", "name": "debug", "resource logs": 1, "log records": 1}
-2024-05-27T12:46:22.423+0200    info    the message app=server
-        {"kind": "exporter", "data_type": "logs", "name": "debug"}
+2024-05-31T13:26:37.531+0200    info    TracesExporter  {"kind": "exporter", "data_type": "traces", "name": "debug", "resource spans": 1, "spans": 2}
+2024-05-31T13:26:37.531+0200    info    okey-dokey-0 082bc2f70f519e32a39fd26ae69b43c0 51201084f4d65159
+lets-go 082bc2f70f519e32a39fd26ae69b43c0 cd321682f3514378
+        {"kind": "exporter", "data_type": "traces", "name": "debug"}
 ```
 
 ### Detailed verbosity

exporter/debugexporter/exporter.go

@@ -30,25 +30,28 @@ type debugExporter struct {
 
 func newDebugExporter(logger *zap.Logger, verbosity configtelemetry.Level) *debugExporter {
 	var logsMarshaler plog.Marshaler
+	var tracesMarshaler ptrace.Marshaler
 	if verbosity == configtelemetry.LevelDetailed {
 		logsMarshaler = otlptext.NewTextLogsMarshaler()
+		tracesMarshaler = otlptext.NewTextTracesMarshaler()
 	} else {
 		logsMarshaler = normal.NewNormalLogsMarshaler()
+		tracesMarshaler = normal.NewNormalTracesMarshaler()
 	}
 	return &debugExporter{
 		verbosity:        verbosity,
 		logger:           logger,
 		logsMarshaler:    logsMarshaler,
 		metricsMarshaler: otlptext.NewTextMetricsMarshaler(),
-		tracesMarshaler:  otlptext.NewTextTracesMarshaler(),
+		tracesMarshaler:  tracesMarshaler,
 	}
 }
 
 func (s *debugExporter) pushTraces(_ context.Context, td ptrace.Traces) error {
 	s.logger.Info("TracesExporter",
 		zap.Int("resource spans", td.ResourceSpans().Len()),
 		zap.Int("spans", td.SpanCount()))
-	if s.verbosity != configtelemetry.LevelDetailed {
+	if s.verbosity == configtelemetry.LevelBasic {
 		return nil
 	}
 

exporter/debugexporter/internal/normal/common.go

@@ -0,0 +1,20 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package normal // import "go.opentelemetry.io/collector/exporter/debugexporter/internal/normal"
+
+import (
+	"fmt"
+
+	"go.opentelemetry.io/collector/pdata/pcommon"
+)
+
+// writeAttributes returns a slice of strings in the form "attrKey=attrValue"
+func writeAttributes(attributes pcommon.Map) (attributeStrings []string) {
+	attributes.Range(func(k string, v pcommon.Value) bool {
+		attribute := fmt.Sprintf("%s=%s", k, v.AsString())
+		attributeStrings = append(attributeStrings, attribute)
+		return true
+	})
+	return attributeStrings
+}

exporter/debugexporter/internal/normal/logs.go

@@ -8,7 +8,6 @@ import (
 	"fmt"
 	"strings"
 
-	"go.opentelemetry.io/collector/pdata/pcommon"
 	"go.opentelemetry.io/collector/pdata/plog"
 )
 
@@ -40,13 +39,3 @@ func (normalLogsMarshaler) MarshalLogs(ld plog.Logs) ([]byte, error) {
 	}
 	return buffer.Bytes(), nil
 }
-
-// writeAttributes returns a slice of strings in the form "attrKey=attrValue"
-func writeAttributes(attributes pcommon.Map) (attributeStrings []string) {
-	attributes.Range(func(k string, v pcommon.Value) bool {
-		attribute := fmt.Sprintf("%s=%s", k, v.AsString())
-		attributeStrings = append(attributeStrings, attribute)
-		return true
-	})
-	return attributeStrings
-}

exporter/debugexporter/internal/normal/traces.go

@@ -0,0 +1,51 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package normal // import "go.opentelemetry.io/collector/exporter/debugexporter/internal/normal"
+
+import (
+	"bytes"
+	"strings"
+
+	"go.opentelemetry.io/collector/pdata/ptrace"
+)
+
+type normalTracesMarshaler struct{}
+
+// Ensure normalTracesMarshaller implements interface ptrace.Marshaler
+var _ ptrace.Marshaler = normalTracesMarshaler{}
+
+// NewNormalTracesMarshaler returns a ptrace.Marshaler for normal verbosity. It writes one line of text per log record
+func NewNormalTracesMarshaler() ptrace.Marshaler {
+	return normalTracesMarshaler{}
+}
+
+func (normalTracesMarshaler) MarshalTraces(md ptrace.Traces) ([]byte, error) {
+	var buffer bytes.Buffer
+	for i := 0; i < md.ResourceSpans().Len(); i++ {
+		resourceTraces := md.ResourceSpans().At(i)
+		for j := 0; j < resourceTraces.ScopeSpans().Len(); j++ {
+			scopeTraces := resourceTraces.ScopeSpans().At(j)
+			for k := 0; k < scopeTraces.Spans().Len(); k++ {
+				span := scopeTraces.Spans().At(k)
+
+				buffer.WriteString(span.Name())
+
+				buffer.WriteString(" ")
+				buffer.WriteString(span.TraceID().String())
+
+				buffer.WriteString(" ")
+				buffer.WriteString(span.SpanID().String())
+
+				if span.Attributes().Len() > 0 {
+					spanAttributes := writeAttributes(span.Attributes())
+					buffer.WriteString(" ")
+					buffer.WriteString(strings.Join(spanAttributes, " "))
+				}
+
+				buffer.WriteString("\n")
+			}
+		}
+	}
+	return buffer.Bytes(), nil
+}

exporter/debugexporter/internal/normal/traces_test.go

@@ -0,0 +1,48 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package normal
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"go.opentelemetry.io/collector/pdata/ptrace"
+)
+
+func TestMarshalTraces(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    ptrace.Traces
+		expected string
+	}{
+		{
+			name:     "empty traces",
+			input:    ptrace.NewTraces(),
+			expected: "",
+		},
+		{
+			name: "one span",
+			input: func() ptrace.Traces {
+				traces := ptrace.NewTraces()
+				span := traces.ResourceSpans().AppendEmpty().ScopeSpans().AppendEmpty().Spans().AppendEmpty()
+				span.SetName("span-name")
+				span.SetTraceID([16]byte{0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x10})
+				span.SetSpanID([8]byte{0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18})
+				span.Attributes().PutStr("key1", "value1")
+				span.Attributes().PutStr("key2", "value2")
+				return traces
+			}(),
+			expected: `span-name 0102030405060708090a0b0c0d0e0f10 1112131415161718 key1=value1 key2=value2
+`,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			output, err := NewNormalTracesMarshaler().MarshalTraces(tt.input)
+			assert.NoError(t, err)
+			assert.Equal(t, tt.expected, string(output))
+		})
+	}
+}