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instrumentation.go
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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
package auto
import (
"context"
"debug/buildinfo"
"errors"
"fmt"
"log/slog"
"os"
"path/filepath"
"runtime"
"strconv"
"strings"
"sync"
"go.opentelemetry.io/contrib/exporters/autoexport"
"go.opentelemetry.io/otel/attribute"
"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
"go.opentelemetry.io/otel/sdk/resource"
"go.opentelemetry.io/otel/sdk/trace"
semconv "go.opentelemetry.io/otel/semconv/v1.26.0"
"go.opentelemetry.io/auto/internal/pkg/instrumentation"
"go.opentelemetry.io/auto/internal/pkg/opentelemetry"
"go.opentelemetry.io/auto/internal/pkg/process"
)
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"
// envTracesExportersKey is the key for the environment variable value
// containing what OpenTelemetry trace exporter to use.
envTracesExportersKey = "OTEL_TRACES_EXPORTER"
// envOtelGlobalImplKey is the key for the environment variable value enabling to opt-in for the
// OpenTelemetry global implementation. It should be a boolean value.
envOtelGlobalImplKey = "OTEL_GO_AUTO_GLOBAL"
// envLogLevelKey is the key for the environment variable value containing the log level.
envLogLevelKey = "OTEL_LOG_LEVEL"
)
// Instrumentation manages and controls all OpenTelemetry Go
// auto-instrumentation.
type Instrumentation struct {
target *process.TargetDetails
analyzer *process.Analyzer
manager *instrumentation.Manager
stopMu sync.Mutex
stop context.CancelFunc
stopped chan struct{}
}
// Error message returned when instrumentation is launched without a valid target
// binary or pid.
var errUndefinedTarget = fmt.Errorf("undefined target Go binary, consider setting the %s environment variable pointing to the target binary to instrument", envTargetExeKey)
// NewInstrumentation returns a new [Instrumentation] configured with the
// provided opts.
//
// If conflicting or duplicate options are provided, the last one will have
// precedence and be used.
func NewInstrumentation(ctx context.Context, opts ...InstrumentationOption) (*Instrumentation, error) {
c, err := newInstConfig(ctx, opts)
if err != nil {
return nil, err
}
if err := c.validate(); err != nil {
return nil, err
}
pa := process.NewAnalyzer(c.logger)
pid, err := pa.DiscoverProcessID(ctx, &c.target)
if err != nil {
return nil, err
}
err = pa.SetBuildInfo(pid)
if err != nil {
return nil, err
}
ctrl, err := opentelemetry.NewController(c.logger, c.tracerProvider(pa.BuildInfo))
if err != nil {
return nil, err
}
cp := convertConfigProvider(c.cp)
mngr, err := instrumentation.NewManager(c.logger, ctrl, c.globalImpl, cp, Version())
if err != nil {
return nil, err
}
td, err := pa.Analyze(pid, mngr.GetRelevantFuncs())
if err != nil {
return nil, err
}
allocDetails, err := process.Allocate(c.logger, pid)
if err != nil {
return nil, err
}
td.AllocationDetails = allocDetails
c.logger.Info(
"target process analysis completed",
"pid", td.PID,
"go_version", td.GoVersion,
"dependencies", td.Libraries,
"total_functions_found", len(td.Functions),
)
mngr.FilterUnusedProbes(td)
return &Instrumentation{
target: td,
analyzer: pa,
manager: mngr,
}, nil
}
// Load loads and attaches the relevant probes to the target process.
func (i *Instrumentation) Load(ctx context.Context) error {
return i.manager.Load(ctx, i.target)
}
// Run starts the instrumentation. It must be called after [Instrumentation.Load].
//
// This function will not return until either ctx is done, an unrecoverable
// error is encountered, or Close is called.
func (i *Instrumentation) Run(ctx context.Context) error {
ctx, err := i.newStop(ctx)
if err != nil {
return err
}
err = i.manager.Run(ctx)
close(i.stopped)
if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
return nil
}
return err
}
func (i *Instrumentation) newStop(parent context.Context) (context.Context, error) {
i.stopMu.Lock()
defer i.stopMu.Unlock()
if i.stop != nil {
return parent, errors.New("instrumentation already running")
}
ctx, stop := context.WithCancel(parent)
i.stop, i.stopped = stop, make(chan struct{})
return ctx, nil
}
// Close closes the Instrumentation, cleaning up all used resources.
func (i *Instrumentation) Close() error {
i.stopMu.Lock()
defer i.stopMu.Unlock()
if i.stop == nil {
// if stop is not set, the instrumentation is not running
// stop the manager to clean up resources
return i.manager.Stop()
}
i.stop()
<-i.stopped
i.stop, i.stopped = nil, nil
return nil
}
// InstrumentationOption applies a configuration option to [Instrumentation].
type InstrumentationOption interface {
apply(context.Context, instConfig) (instConfig, error)
}
type instConfig struct {
traceExp trace.SpanExporter
target process.TargetArgs
serviceName string
additionalResAttrs []attribute.KeyValue
globalImpl bool
logger *slog.Logger
sampler Sampler
cp ConfigProvider
}
func newInstConfig(ctx context.Context, opts []InstrumentationOption) (instConfig, error) {
var (
c instConfig
err error
)
for _, opt := range opts {
if opt != nil {
var e error
c, e = opt.apply(ctx, c)
err = errors.Join(err, e)
}
}
// Defaults.
if c.serviceName == "" {
c.serviceName = c.defaultServiceName()
}
if c.traceExp == nil {
var e error
// This is the OTel recommended default.
c.traceExp, e = otlptracehttp.New(ctx)
err = errors.Join(err, e)
}
if c.sampler == nil {
c.sampler = DefaultSampler()
}
if c.logger == nil {
c.logger = newLogger(nil)
}
if c.cp == nil {
c.cp = newNoopConfigProvider(c.sampler)
}
return c, err
}
func (c instConfig) defaultServiceName() string {
name := "unknown_service"
if c.target.ExePath != "" {
name = fmt.Sprintf("%s:%s", name, filepath.Base(c.target.ExePath))
}
return name
}
func (c instConfig) validate() error {
var zero process.TargetArgs
if c.target == zero {
return errUndefinedTarget
}
if c.traceExp == nil {
return errors.New("undefined trace exporter")
}
return c.target.Validate()
}
func (c instConfig) tracerProvider(bi *buildinfo.BuildInfo) *trace.TracerProvider {
return trace.NewTracerProvider(
// the actual sampling is done in the eBPF probes.
// this is just to make sure that we export all spans we get from the probes
trace.WithSampler(trace.AlwaysSample()),
trace.WithResource(c.res(bi)),
trace.WithBatcher(c.traceExp),
trace.WithIDGenerator(opentelemetry.NewEBPFSourceIDGenerator()),
)
}
func (c instConfig) res(bi *buildinfo.BuildInfo) *resource.Resource {
runVer := bi.GoVersion
var compiler string
for _, setting := range bi.Settings {
if setting.Key == "-compiler" {
compiler = setting.Value
break
}
}
runName := compiler
if runName == "gc" {
runName = "go"
}
runDesc := fmt.Sprintf(
"go version %s %s/%s",
runVer, runtime.GOOS, runtime.GOARCH,
)
attrs := []attribute.KeyValue{
semconv.ServiceNameKey.String(c.serviceName),
semconv.TelemetrySDKLanguageGo,
semconv.TelemetryDistroVersionKey.String(Version()),
semconv.TelemetryDistroNameKey.String("opentelemetry-go-instrumentation"),
semconv.ProcessRuntimeName(runName),
semconv.ProcessRuntimeVersion(runVer),
semconv.ProcessRuntimeDescription(runDesc),
}
if len(c.additionalResAttrs) > 0 {
attrs = append(attrs, c.additionalResAttrs...)
}
return resource.NewWithAttributes(
semconv.SchemaURL,
attrs...,
)
}
// newLogger is used for testing.
var newLogger = newLoggerFunc
func newLoggerFunc(level slog.Leveler) *slog.Logger {
opts := &slog.HandlerOptions{AddSource: true, Level: level}
h := slog.NewJSONHandler(os.Stderr, opts)
return slog.New(h)
}
type fnOpt func(context.Context, instConfig) (instConfig, error)
func (o fnOpt) apply(ctx context.Context, c instConfig) (instConfig, error) { return o(ctx, c) }
// WithTarget returns an [InstrumentationOption] defining the target binary for
// [Instrumentation] that is being executed at the provided path.
//
// This option conflicts with [WithPID]. If both are used, the last one
// provided to an [Instrumentation] will 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, this option will conflict with
// [WithEnv]. If both are used, the last one provided to an [Instrumentation]
// will be used.
func WithTarget(path string) InstrumentationOption {
return fnOpt(func(_ context.Context, c instConfig) (instConfig, error) {
c.target = process.TargetArgs{ExePath: path}
return c, nil
})
}
// 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 or the service name is defined in
// OTEL_RESOURCE_ATTRIBUTES, this option will conflict with [WithEnv]. If both
// are used, the last one provided to an [Instrumentation] will be used.
func WithServiceName(serviceName string) InstrumentationOption {
return fnOpt(func(_ context.Context, c instConfig) (instConfig, error) {
c.serviceName = serviceName
return c, nil
})
}
// WithPID returns an [InstrumentationOption] defining the target binary for
// [Instrumentation] that is being run with the provided PID.
//
// This option conflicts with [WithTarget]. If both are used, the last one
// provided to an [Instrumentation] will 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, this option will conflict with
// [WithEnv]. If both are used, the last one provided to an [Instrumentation]
// will be used.
func WithPID(pid int) InstrumentationOption {
return fnOpt(func(_ context.Context, c instConfig) (instConfig, error) {
c.target = process.TargetArgs{Pid: pid}
return c, nil
})
}
var lookupEnv = os.LookupEnv
// WithEnv returns an [InstrumentationOption] that will configure
// [Instrumentation] using the values defined by the following environment
// variables:
//
// - OTEL_GO_AUTO_TARGET_EXE: sets the target binary
// - OTEL_SERVICE_NAME (or OTEL_RESOURCE_ATTRIBUTES): sets the service name
// - OTEL_TRACES_EXPORTER: sets the trace exporter
// - OTEL_GO_AUTO_GLOBAL: enables the OpenTelemetry global implementation
// - OTEL_LOG_LEVEL: sets the default logger's minimum logging level
// - OTEL_TRACES_SAMPLER: sets the trace sampler
// - OTEL_TRACES_SAMPLER_ARG: optionally sets the trace sampler argument
//
// This option may conflict with [WithTarget], [WithPID], [WithTraceExporter],
// [WithServiceName], [WithGlobal], and [WithSampler] if their respective environment variable is defined.
// If more than one of these options are used, the last one provided to an
// [Instrumentation] will be used.
//
// If [WithLogger] is used, OTEL_LOG_LEVEL will not be used for the
// [Instrumentation] logger. Instead, the [slog.Logger] passed to that option
// will be used as-is.
//
// If [WithLogger] is not used, OTEL_LOG_LEVEL will be parsed and the default
// logger used by the configured [Instrumentation] will use that level as its
// minimum logging level.
//
// The OTEL_TRACES_EXPORTER environment variable value is resolved using the
// [autoexport] package. See that package's documentation for information on
// supported values and registration of custom exporters.
func WithEnv() InstrumentationOption {
return fnOpt(func(ctx context.Context, c instConfig) (instConfig, error) {
var err error
if v, ok := lookupEnv(envTargetExeKey); ok {
c.target = process.TargetArgs{ExePath: v}
}
if _, ok := lookupEnv(envTracesExportersKey); ok {
// Don't track the lookup value because autoexport does not provide
// a way to just pass the environment value currently. Just use
// NewSpanExporter which will re-read this value.
var e error
// NewSpanExporter will use an OTLP (HTTP/protobuf) exporter as the
// default. This is the OTel recommended default.
c.traceExp, e = autoexport.NewSpanExporter(ctx)
err = errors.Join(err, e)
}
if name, attrs, ok := lookupResourceData(); ok {
c.serviceName = name
c.additionalResAttrs = append(c.additionalResAttrs, attrs...)
}
if val, ok := lookupEnv(envOtelGlobalImplKey); ok {
boolVal, err := strconv.ParseBool(val)
if err == nil {
c.globalImpl = boolVal
}
}
if val, ok := lookupEnv(envLogLevelKey); c.logger == nil && ok {
var level slog.Level
if e := level.UnmarshalText([]byte(val)); e != nil {
e = fmt.Errorf("parse log level %q: %w", val, e)
err = errors.Join(err, e)
} else {
c.logger = newLogger(level)
}
}
if s, e := newSamplerFromEnv(lookupEnv); e != nil {
err = errors.Join(err, e)
} else {
c.sampler = s
}
return c, err
})
}
func lookupResourceData() (string, []attribute.KeyValue, bool) {
// Prioritize OTEL_SERVICE_NAME over OTEL_RESOURCE_ATTRIBUTES value.
svcName := ""
if v, ok := lookupEnv(envServiceNameKey); ok {
svcName = v
}
v, ok := lookupEnv(envResourceAttrKey)
if !ok {
return svcName, nil, svcName != ""
}
var attrs []attribute.KeyValue
for _, keyval := range strings.Split(strings.TrimSpace(v), ",") {
key, val, found := strings.Cut(keyval, "=")
if !found {
continue
}
key = strings.TrimSpace(key)
if key == string(semconv.ServiceNameKey) {
svcName = strings.TrimSpace(val)
} else {
attrs = append(attrs, attribute.String(key, strings.TrimSpace(val)))
}
}
if svcName == "" {
return "", nil, false
}
return svcName, attrs, true
}
// WithTraceExporter returns an [InstrumentationOption] that will configure an
// [Instrumentation] to use the provided exp to export OpenTelemetry tracing
// telemetry.
//
// If OTEL_TRACES_EXPORTER is defined, this option will conflict with
// [WithEnv]. If both are used, the last one provided to an [Instrumentation]
// will be used.
func WithTraceExporter(exp trace.SpanExporter) InstrumentationOption {
return fnOpt(func(_ context.Context, c instConfig) (instConfig, error) {
c.traceExp = exp
return c, nil
})
}
// WithSampler returns an [InstrumentationOption] that will configure
// an [Instrumentation] to use the provided sampler to sample OpenTelemetry traces.
//
// This currently is a no-op. It is expected to take effect in the next release.
func WithSampler(sampler Sampler) InstrumentationOption {
return fnOpt(func(_ context.Context, c instConfig) (instConfig, error) {
c.sampler = sampler
return c, nil
})
}
// WithGlobal returns an [InstrumentationOption] that will configure an
// [Instrumentation] to record telemetry from the [OpenTelemetry default global
// implementation]. By default, the OpenTelemetry global implementation is a
// no-op implementation of the OpenTelemetry API. However, by using this
// option, all telemetry that would have been dropped by the global
// implementation will be recorded using telemetry pipelines from the
// configured [Instrumentation].
//
// If the target process overrides the default global implementation (e.g.
// [otel.SetTracerProvider]), the telemetry from that process will go to the
// set implementation. It will not be recorded using the telemetry pipelines
// from the configured [Instrumentation] even if this option is used.
//
// The OpenTelemetry default global implementation is left unchanged (i.e. it
// remains a no-op implementation) if this options is not used.
//
// If OTEL_GO_AUTO_GLOBAL is defined, this option will conflict with
// [WithEnv]. If both are used, the last one provided to an [Instrumentation]
// will be used.
//
// [OpenTelemetry default global implementation]: https://pkg.go.dev/go.opentelemetry.io/otel
func WithGlobal() InstrumentationOption {
return fnOpt(func(_ context.Context, c instConfig) (instConfig, error) {
c.globalImpl = true
return c, nil
})
}
// WithResourceAttributes returns an [InstrumentationOption] that will configure
// an [Instrumentation] to add the provided attributes to the OpenTelemetry resource.
func WithResourceAttributes(attrs ...attribute.KeyValue) InstrumentationOption {
return fnOpt(func(_ context.Context, c instConfig) (instConfig, error) {
c.additionalResAttrs = append(c.additionalResAttrs, attrs...)
return c, nil
})
}
// WithLogger returns an [InstrumentationOption] that will configure an
// [Instrumentation] to use the provided logger.
//
// If this option is used and [WithEnv] is also used, OTEL_LOG_LEVEL is ignored
// by the configured [Instrumentation]. This passed logger takes precedence and
// is used as-is.
//
// If this option is not used, the [Instrumentation] will use an [slog.Loogger]
// backed by an [slog.JSONHandler] outputting to STDERR as a default.
func WithLogger(logger *slog.Logger) InstrumentationOption {
return fnOpt(func(_ context.Context, c instConfig) (instConfig, error) {
c.logger = logger
return c, nil
})
}
// WithConfigProvider returns an [InstrumentationOption] that will configure
// an [Instrumentation] to use the provided ConfigProvider. The ConfigProvider
// is used to provide the initial configuration and update the configuration of
// the instrumentation in runtime.
func WithConfigProvider(cp ConfigProvider) InstrumentationOption {
return fnOpt(func(_ context.Context, c instConfig) (instConfig, error) {
c.cp = cp
return c, nil
})
}