Add WithServiceName and WithPid as config options for instrumentation…

instrumentation.go

@@ -25,9 +25,13 @@ import (
 	"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"
+)
 
 // Instrumentation manages and controls all OpenTelemetry Go
 // auto-instrumentation.
@@ -41,6 +45,8 @@ var (
 	// Error message returned when instrumentation is launched without a target
 	// binary.
 	errUndefinedTarget = fmt.Errorf("undefined target Go binary, consider setting the %s environment variable pointing to the target binary to instrument", envTargetExeKey)
+	// Error message returned when no service name is specified.
+	errUndefinedServiceName = fmt.Errorf("undefined service name, consider setting %s", envServiceNameKey)
 )
 
 // NewInstrumentation returns a new [Instrumentation] configured with the
@@ -57,7 +63,7 @@ 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
 	}
@@ -106,7 +112,8 @@ type InstrumentationOption interface {
 }
 
 type instConfig struct {
-	target *process.TargetArgs
+	target      *process.TargetArgs
+	serviceName string
 }
 
 func newInstConfig(opts []InstrumentationOption) instConfig {
@@ -122,13 +129,19 @@ 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
+	}
 	return c
 }
 
 func (c instConfig) validate() error {
 	if c.target == nil {
 		return errUndefinedTarget
 	}
+	if c.serviceName == "" {
+		return errUndefinedServiceName
+	}
 	return c.target.Validate()
 }
 
@@ -150,3 +163,39 @@ 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
+	})
+}
+
+// WithPID returns an [InstrumentationOption] corresponding to the executable
+// used by the provided pid.
+//
+// This option conflicts with [WithTarget]. If both are used, the last one
+// passed to [Instrumentation] will take precedence and be used.
+//
+// If multiple of these options are provided to an [Instrumentation], the last
+// one will be used.
+//
+// If OTEL_GO_AUTO_TARGET_EXE is defined it will take precedence over any value
+// passed here.
+func WithPID(pid int) InstrumentationOption {
+	exeLinkPath := fmt.Sprintf("/proc/%d/exe", pid)
+	exePath, err := os.Readlink(exeLinkPath)
+	if err != nil {
+		log.Logger.Error(err, "Failed to read exe link for process", "pid", pid)
+		exePath = ""
+	}
+
+	return WithTarget(exePath)
+}

internal/pkg/instrumentors/allocator/allocator_linux.go

@@ -18,6 +18,7 @@ import (
 	"go.opentelemetry.io/auto/internal/pkg/instrumentors/bpffs"
 	"go.opentelemetry.io/auto/internal/pkg/instrumentors/context"
 	"go.opentelemetry.io/auto/internal/pkg/log"
+	"go.opentelemetry.io/auto/internal/pkg/process"
 )
 
 // Allocator handles the allocation of the BPF file-system.
@@ -45,3 +46,7 @@ func (a *Allocator) Load(ctx *context.InstrumentorContext) error {
 
 	return nil
 }
+
+func (a *Allocator) Clean(target *process.TargetDetails) error {
+	return bpffs.Cleanup(target)
+}

internal/pkg/instrumentors/runner.go

@@ -47,11 +47,11 @@ func (m *Manager) Run(ctx context.Context, target *process.TargetDetails) error
 		select {
 		case <-ctx.Done():
 			m.Close()
-			m.cleanup()
+			m.cleanup(target)
 			return ctx.Err()
 		case <-m.done:
 			log.Logger.V(0).Info("shutting down all instrumentors due to signal")
-			m.cleanup()
+			m.cleanup(target)
 			return nil
 		case e := <-m.incomingEvents:
 			m.otelController.Trace(e)
@@ -91,7 +91,7 @@ func (m *Manager) load(target *process.TargetDetails) error {
 		err := i.Load(ctx)
 		if err != nil {
 			log.Logger.Error(err, "error while loading instrumentors, cleaning up", "name", name)
-			m.cleanup()
+			m.cleanup(target)
 			return err
 		}
 	}
@@ -100,11 +100,18 @@ func (m *Manager) load(target *process.TargetDetails) error {
 	return nil
 }
 
-func (m *Manager) cleanup() {
+func (m *Manager) cleanup(target *process.TargetDetails) {
 	close(m.incomingEvents)
 	for _, i := range m.instrumentors {
 		i.Close()
 	}
+
+	log.Logger.V(0).Info("Cleaning bpffs")
+	err := m.allocator.Clean(target)
+
+	if err != nil {
+		log.Logger.Error(err, "Failed to clean bpffs")
+	}
 }
 
 // Close closes m.

internal/pkg/opentelemetry/controller.go

@@ -17,7 +17,6 @@ package opentelemetry
 import (
 	"context"
 	"fmt"
-	"os"
 	"runtime"
 	"strings"
 	"time"
@@ -35,10 +34,6 @@ import (
 	"go.opentelemetry.io/otel/trace"
 )
 
-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)
 
@@ -89,12 +84,7 @@ 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(

internal/pkg/process/discover.go

@@ -16,7 +16,6 @@ package process
 
 import (
 	"io"
-	"io/ioutil"
 	"os"
 	"path"
 	"strconv"
@@ -97,7 +96,7 @@ func (a *Analyzer) findProcessID(target *TargetArgs) (int, error) {
 			exeName, err := os.Readlink(path.Join("/proc", dname, "exe"))
 			if err != nil {
 				// Read link may fail if target process runs not as root
-				cmdLine, err := ioutil.ReadFile(path.Join("/proc", dname, "cmdline"))
+				cmdLine, err := os.ReadFile(path.Join("/proc", dname, "cmdline"))
 				if err != nil {
 					return 0, err
 				}