[cmd/telemetrygen] Add exemplars support for telemetrygen (open-telem…

…etry#33320)

This PR adds support for passing a traceID and spanID to be used as
exemplars on the generated data points. This was verified with an e2e
test using OTel Collector and the debug exporter in detailed verbosity,
resulting in this:

```
2024-05-31T11:41:51.378+0200    info    ResourceMetrics #0
Resource SchemaURL: https://opentelemetry.io/schemas/1.13.0
ScopeMetrics #0
ScopeMetrics SchemaURL: 
InstrumentationScope  
Metric #0
Descriptor:
     -> Name: gen
     -> Description: 
     -> Unit: 
     -> DataType: Gauge
NumberDataPoints #0
StartTimestamp: 1970-01-01 00:00:00 +0000 UTC
Timestamp: 2024-05-31 09:41:51.374564535 +0000 UTC
Value: 0
Exemplars:
Exemplar #0
     -> Trace ID: ae87dadd90e9935a4bc9660628efd569
     -> Span ID: 5828fa4960140870
     -> Timestamp: 2024-05-31 09:41:51.374432029 +0000 UTC
     -> Value: 1
```

Given that I needed to do the validation of the traceID/spanID on the
metrics config as well, I refactored the current validation done in the
logging part of the command so that it's now part of the common package.

Signed-off-by: Juraci Paixão Kröhling <[email protected]>

---------

Signed-off-by: Juraci Paixão Kröhling <[email protected]>

.chloggen/add-traceid-spanid-exemplars-telemetrygen.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: cmd/telemetrygen
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add support for adding spanID and traceID as exemplars to datapoints generated by telemetrygen
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [33320]
+
+# (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: []

cmd/telemetrygen/internal/common/validate.go

@@ -0,0 +1,41 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package common
+
+import (
+	"encoding/hex"
+	"fmt"
+)
+
+var (
+	errInvalidTraceIDLenght = fmt.Errorf("TraceID must be a 32 character hex string, like: 'ae87dadd90e9935a4bc9660628efd569'")
+	errInvalidSpanIDLenght  = fmt.Errorf("SpanID must be a 16 character hex string, like: '5828fa4960140870'")
+	errInvalidTraceID       = fmt.Errorf("failed to create traceID byte array from the given traceID, make sure the traceID is a hex representation of a [16]byte, like: 'ae87dadd90e9935a4bc9660628efd569'")
+	errInvalidSpanID        = fmt.Errorf("failed to create SpanID byte array from the given SpanID, make sure the SpanID is a hex representation of a [8]byte, like: '5828fa4960140870'")
+)
+
+func ValidateTraceID(traceID string) error {
+	if len(traceID) != 32 {
+		return errInvalidTraceIDLenght
+	}
+
+	_, err := hex.DecodeString(traceID)
+	if err != nil {
+		return errInvalidTraceID
+	}
+
+	return nil
+}
+
+func ValidateSpanID(spanID string) error {
+	if len(spanID) != 16 {
+		return errInvalidSpanIDLenght
+	}
+	_, err := hex.DecodeString(spanID)
+	if err != nil {
+		return errInvalidSpanID
+	}
+
+	return nil
+}

cmd/telemetrygen/internal/common/validate_test.go

@@ -0,0 +1,70 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package common
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestValidateTraceID(t *testing.T) {
+	tests := []struct {
+		name     string
+		traceID  string
+		expected error
+	}{
+		{
+			name:     "Valid",
+			traceID:  "ae87dadd90e9935a4bc9660628efd569",
+			expected: nil,
+		},
+		{
+			name:     "InvalidLength",
+			traceID:  "invalid-length",
+			expected: errInvalidTraceIDLenght,
+		},
+		{
+			name:     "InvalidTraceID",
+			traceID:  "zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz",
+			expected: errInvalidTraceID,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := ValidateTraceID(tt.traceID)
+			assert.ErrorIs(t, err, tt.expected)
+		})
+	}
+}
+
+func TestValidateSpanID(t *testing.T) {
+	tests := []struct {
+		name     string
+		spanID   string
+		expected error
+	}{
+		{
+			name:     "Valid",
+			spanID:   "5828fa4960140870",
+			expected: nil,
+		},
+		{
+			name:     "InvalidLength",
+			spanID:   "invalid-length",
+			expected: errInvalidSpanIDLenght,
+		},
+		{
+			name:     "InvalidTraceID",
+			spanID:   "zzzzzzzzzzzzzzzz",
+			expected: errInvalidSpanID,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := ValidateSpanID(tt.spanID)
+			assert.ErrorIs(t, err, tt.expected)
+		})
+	}
+}

cmd/telemetrygen/internal/logs/config.go

@@ -4,8 +4,6 @@
 package logs
 
 import (
-	"encoding/hex"
-
 	"github.com/spf13/pflag"
 
 	"github.com/open-telemetry/opentelemetry-collector-contrib/cmd/telemetrygen/internal/common"
@@ -39,23 +37,14 @@ func (c *Config) Flags(fs *pflag.FlagSet) {
 // Validate validates the test scenario parameters.
 func (c *Config) Validate() error {
 	if c.TraceID != "" {
-		if len(c.TraceID) != 32 {
-			return errInvalidTraceIDLenght
-		}
-
-		_, err := hex.DecodeString(c.TraceID)
-		if err != nil {
-			return errInvalidTraceID
+		if err := common.ValidateTraceID(c.TraceID); err != nil {
+			return err
 		}
 	}
 
 	if c.SpanID != "" {
-		if len(c.SpanID) != 16 {
-			return errInvalidSpanIDLenght
-		}
-		_, err := hex.DecodeString(c.SpanID)
-		if err != nil {
-			return errInvalidSpanID
+		if err := common.ValidateSpanID(c.SpanID); err != nil {
+			return err
 		}
 	}
 

cmd/telemetrygen/internal/logs/logs.go

@@ -18,13 +18,6 @@ import (
 	"github.com/open-telemetry/opentelemetry-collector-contrib/cmd/telemetrygen/internal/common"
 )
 
-var (
-	errInvalidTraceIDLenght = fmt.Errorf("TraceID must be a 32 character hex string, like: 'ae87dadd90e9935a4bc9660628efd569'")
-	errInvalidSpanIDLenght  = fmt.Errorf("SpanID must be a 16 character hex string, like: '5828fa4960140870'")
-	errInvalidTraceID       = fmt.Errorf("failed to create traceID byte array from the given traceID, make sure the traceID is a hex representation of a [16]byte, like: 'ae87dadd90e9935a4bc9660628efd569'")
-	errInvalidSpanID        = fmt.Errorf("failed to create SpanID byte array from the given SpanID, make sure the SpanID is a hex representation of a [8]byte, like: '5828fa4960140870'")
-)
-
 // Start starts the log telemetry generator
 func Start(cfg *Config) error {
 	logger, err := common.CreateLogger(cfg.SkipSettingGRPCLogger)

cmd/telemetrygen/internal/metrics/config.go

@@ -15,6 +15,8 @@ type Config struct {
 	NumMetrics int
 	MetricName string
 	MetricType metricType
+	SpanID     string
+	TraceID    string
 }
 
 // Flags registers config flags.
@@ -29,4 +31,25 @@ func (c *Config) Flags(fs *pflag.FlagSet) {
 
 	fs.Var(&c.MetricType, "metric-type", "Metric type enum. must be one of 'Gauge' or 'Sum'")
 	fs.IntVar(&c.NumMetrics, "metrics", 1, "Number of metrics to generate in each worker (ignored if duration is provided)")
+
+	fs.StringVar(&c.TraceID, "trace-id", "", "TraceID to use as exemplar")
+	fs.StringVar(&c.SpanID, "span-id", "", "SpanID to use as exemplar")
+
+}
+
+// Validate validates the test scenario parameters.
+func (c *Config) Validate() error {
+	if c.TraceID != "" {
+		if err := common.ValidateTraceID(c.TraceID); err != nil {
+			return err
+		}
+	}
+
+	if c.SpanID != "" {
+		if err := common.ValidateSpanID(c.SpanID); err != nil {
+			return err
+		}
+	}
+
+	return nil
 }

cmd/telemetrygen/internal/metrics/metrics.go

@@ -5,6 +5,7 @@ package metrics
 
 import (
 	"context"
+	"encoding/hex"
 	"fmt"
 	"sync"
 	"sync/atomic"
@@ -14,6 +15,7 @@ import (
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc"
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp"
 	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
+	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 	"go.opentelemetry.io/otel/sdk/resource"
 	"go.uber.org/zap"
 	"golang.org/x/time/rate"
@@ -95,6 +97,7 @@ func Run(c *Config, exp func() (sdkmetric.Exporter, error), logger *zap.Logger)
 			numMetrics:     c.NumMetrics,
 			metricName:     c.MetricName,
 			metricType:     c.MetricType,
+			exemplars:      exemplarsFromConfig(c),
 			limitPerSecond: limit,
 			totalDuration:  c.TotalDuration,
 			running:        running,
@@ -112,3 +115,31 @@ func Run(c *Config, exp func() (sdkmetric.Exporter, error), logger *zap.Logger)
 	wg.Wait()
 	return nil
 }
+
+func exemplarsFromConfig(c *Config) []metricdata.Exemplar[int64] {
+	if c.TraceID != "" || c.SpanID != "" {
+		var exemplars []metricdata.Exemplar[int64]
+
+		exemplar := metricdata.Exemplar[int64]{
+			Value: 1,
+			Time:  time.Now(),
+		}
+
+		if c.TraceID != "" {
+			// we validated this already during the Validate() function for config
+			// nolint: errcheck
+			traceID, _ := hex.DecodeString(c.TraceID)
+			exemplar.TraceID = traceID
+		}
+
+		if c.SpanID != "" {
+			// we validated this already during the Validate() function for config
+			// nolint: errcheck
+			spanID, _ := hex.DecodeString(c.SpanID)
+			exemplar.SpanID = spanID
+		}
+
+		return append(exemplars, exemplar)
+	}
+	return nil
+}