Add WithServiceName config option for instrumentation

CHANGELOG.md

@@ -8,6 +8,10 @@ OpenTelemetry Go Automatic Instrumentation adheres to [Semantic Versioning](http
 
 ## [Unreleased]
 
+### Added
+
+- Add `WithServiceName` config option for instrumentation. ([#353](https://github.com/open-telemetry/opentelemetry-go-instrumentation/pull/353))
+
 ### Changed
 
 - Fix runtime panic if OTEL_GO_AUTO_TARGET_EXE is not set. ([#339](https://github.com/open-telemetry/opentelemetry-go-instrumentation/pull/339))

instConfig_test.go

@@ -0,0 +1,55 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package auto
+
+import (
+	"fmt"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	semconv "go.opentelemetry.io/otel/semconv/v1.21.0"
+)
+
+func TestWithServiceName(t *testing.T) {
+	testServiceName := "test_serviceName"
+
+	// Use WithServiceName to config the service name
+	c := newInstConfig([]InstrumentationOption{WithServiceName((testServiceName))})
+	assert.Equal(t, testServiceName, c.serviceName)
+
+	// No service name provided - check for default value
+	c = newInstConfig([]InstrumentationOption{})
+	assert.Equal(t, serviceNameDefault, c.serviceName)
+
+	// OTEL_RESOURCE_ATTRIBUTES
+	resServiceName := "resValue"
+	err := os.Setenv(envResourceAttrKey, fmt.Sprintf("key1=val1,%s=%s", string(semconv.ServiceNameKey), resServiceName))
+	if err != nil {
+		t.Error(err)
+	}
+	c = newInstConfig([]InstrumentationOption{WithServiceName((testServiceName))})
+	assert.Equal(t, resServiceName, c.serviceName)
+
+	// Add env var to take precedence
+	envServiceName := "env_serviceName"
+	err = os.Setenv(envServiceNameKey, envServiceName)
+	if err != nil {
+		t.Error(err)
+	}
+	c = newInstConfig([]InstrumentationOption{WithServiceName((testServiceName))})
+	assert.Equal(t, envServiceName, c.serviceName)
+}

instrumentation.go

@@ -18,16 +18,29 @@ import (
 	"context"
 	"fmt"
 	"os"
+	"path/filepath"
+	"strings"
+
+	semconv "go.opentelemetry.io/otel/semconv/v1.21.0"
 
 	"go.opentelemetry.io/auto/internal/pkg/instrumentors"
 	"go.opentelemetry.io/auto/internal/pkg/log"
 	"go.opentelemetry.io/auto/internal/pkg/opentelemetry"
 	"go.opentelemetry.io/auto/internal/pkg/process"
 )
 
-// envTargetExeKey is the key for the environment variable value pointing to the
-// target binary to instrument.
-const envTargetExeKey = "OTEL_GO_AUTO_TARGET_EXE"
+const (
+	// envTargetExeKey is the key for the environment variable value pointing to the
+	// target binary to instrument.
+	envTargetExeKey = "OTEL_GO_AUTO_TARGET_EXE"
+	// envServiceName is the key for the envoriment variable value containing the service name.
+	envServiceNameKey = "OTEL_SERVICE_NAME"
+	// envResourceAttrKey is the key for the environment variable value containing
+	// OpenTelemetry Resource attributes.
+	envResourceAttrKey = "OTEL_RESOURCE_ATTRIBUTES"
+	// serviceNameDefault is the default service name prefix used if a user does not provide one.
+	serviceNameDefault = "unknown_service"
+)
 
 // Instrumentation manages and controls all OpenTelemetry Go
 // auto-instrumentation.
@@ -55,7 +68,7 @@ func NewInstrumentation(opts ...InstrumentationOption) (*Instrumentation, error)
 		return nil, err
 	}
 
-	ctrl, err := opentelemetry.NewController(Version())
+	ctrl, err := opentelemetry.NewController(Version(), c.serviceName)
 	if err != nil {
 		return nil, err
 	}
@@ -104,7 +117,8 @@ type InstrumentationOption interface {
 }
 
 type instConfig struct {
-	target *process.TargetArgs
+	target      *process.TargetArgs
+	serviceName string
 }
 
 func newInstConfig(opts []InstrumentationOption) instConfig {
@@ -120,6 +134,45 @@ func (c instConfig) applyEnv() instConfig {
 	if v, ok := os.LookupEnv(envTargetExeKey); ok {
 		c.target = &process.TargetArgs{ExePath: v}
 	}
+	if v, ok := os.LookupEnv(envServiceNameKey); ok {
+		c.serviceName = v
+	} else {
+		c = c.applyResourceAtrrEnv()
+		if c.serviceName == "" {
+			c = c.setDefualtServiceName()
+		}
+	}
+	return c
+}
+
+func (c instConfig) setDefualtServiceName() instConfig {
+	if c.target != nil {
+		c.serviceName = fmt.Sprintf("%s:%s", serviceNameDefault, filepath.Base(c.target.ExePath))
+	} else {
+		c.serviceName = serviceNameDefault
+	}
+	return c
+}
+
+func (c instConfig) applyResourceAtrrEnv() instConfig {
+	attrs := strings.TrimSpace(os.Getenv(envResourceAttrKey))
+
+	if attrs == "" {
+		return c
+	}
+
+	pairs := strings.Split(attrs, ",")
+	for _, p := range pairs {
+		k, v, found := strings.Cut(p, "=")
+		if !found {
+			continue
+		}
+		key := strings.TrimSpace(k)
+		if key == string(semconv.ServiceNameKey) {
+			c.serviceName = strings.TrimSpace(v)
+		}
+	}
+
 	return c
 }
 
@@ -148,3 +201,17 @@ func WithTarget(path string) InstrumentationOption {
 		return c
 	})
 }
+
+// WithServiceName returns an [InstrumentationOption] defining the name of the service running.
+//
+// If multiple of these options are provided to an [Instrumentation], the last
+// one will be used.
+//
+// If OTEL_SERVICE_NAME is defined it will take precedence over any value
+// passed here.
+func WithServiceName(serviceName string) InstrumentationOption {
+	return fnOpt(func(c instConfig) instConfig {
+		c.serviceName = serviceName
+		return c
+	})
+}

internal/pkg/opentelemetry/controller.go

@@ -17,7 +17,6 @@ package opentelemetry
 import (
 	"context"
 	"fmt"
-	"os"
 	"runtime"
 	"strings"
 	"time"
@@ -36,10 +35,6 @@ import (
 	"go.opentelemetry.io/auto/internal/pkg/log"
 )
 
-const (
-	otelServiceNameEnvVar = "OTEL_SERVICE_NAME"
-)
-
 // Information about the runtime environment for inclusion in User-Agent, e.g. "go/1.18.2 (linux/amd64)".
 var runtimeInfo = fmt.Sprintf("%s (%s/%s)", strings.Replace(runtime.Version(), "go", "go/", 1), runtime.GOOS, runtime.GOARCH)
 
@@ -90,12 +85,7 @@ func (c *Controller) convertTime(t int64) time.Time {
 }
 
 // NewController returns a new initialized [Controller].
-func NewController(version string) (*Controller, error) {
-	serviceName, exists := os.LookupEnv(otelServiceNameEnvVar)
-	if !exists {
-		return nil, fmt.Errorf("%s env var must be set", otelServiceNameEnvVar)
-	}
-
+func NewController(version string, serviceName string) (*Controller, error) {
 	ctx := context.Background()
 	res, err := resource.New(ctx,
 		resource.WithAttributes(