add environment variable option for language selection (#1331)

Author: grcevski

internal/test/integration/docker-compose-nodeclient.yml

@@ -33,7 +33,7 @@ services:
     environment:
       GOCOVERDIR: "/coverage"
       OTEL_EBPF_TRACE_PRINTER: "text"
-      OTEL_EBPF_EXECUTABLE_PATH: "${OTEL_EBPF_EXECUTABLE_PATH}"
+      OTEL_EBPF_AUTO_TARGET_LANGUAGE: "nodejs"
       OTEL_EBPF_SERVICE_NAMESPACE: "integration-test"
       OTEL_EBPF_DISCOVERY_POLL_INTERVAL: 500ms
       OTEL_EBPF_OTLP_TRACES_BATCH_TIMEOUT: "1ms"

pkg/appolly/discover/matcher.go

@@ -368,13 +368,14 @@ func FindingCriteria(cfg *obi.Config) []services.Selector {
 
 	if len(cfg.Discovery.Instrument) > 0 {
 		finderCriteria := cfg.Discovery.Instrument
-		if cfg.AutoTargetExe.IsSet() || cfg.Port.Len() > 0 {
+		if cfg.AutoTargetExe.IsSet() || cfg.Port.Len() > 0 || cfg.AutoTargetLanguage.IsSet() {
 			finderCriteria = slices.Clone(cfg.Discovery.Instrument)
 			finderCriteria = append(finderCriteria, services.GlobAttributes{
 				Name:      cfg.ServiceName,
 				Namespace: cfg.ServiceNamespace,
 				Path:      cfg.AutoTargetExe,
 				OpenPorts: cfg.Port,
+				Languages: cfg.AutoTargetLanguage,
 			})
 		}
 		return NormalizeGlobCriteria(finderCriteria)
@@ -383,13 +384,14 @@ func FindingCriteria(cfg *obi.Config) []services.Selector {
 	// edge use case: when neither discovery > services nor discovery > instrument sections are set
 	// we will prioritize the newer OTEL_EBPF_AUTO_TARGET_EXE/OTEL_GO_AUTO_TARGET_EXE property
 	// over the old, deprecated OTEL_EBPF_EXECUTABLE_PATH
-	if cfg.AutoTargetExe.IsSet() {
+	if cfg.AutoTargetExe.IsSet() || cfg.AutoTargetLanguage.IsSet() {
 		return []services.Selector{
 			&services.GlobAttributes{
 				Name:      cfg.ServiceName,
 				Namespace: cfg.ServiceNamespace,
 				Path:      cfg.AutoTargetExe,
 				OpenPorts: cfg.Port,
+				Languages: cfg.AutoTargetLanguage,
 			},
 		}
 	}

pkg/obi/config.go

@@ -292,6 +292,10 @@ type Config struct {
 	// will instrument all the service calls in all the ports, not only the port specified here.
 	Port services.PortEnum `yaml:"open_port" env:"OTEL_EBPF_OPEN_PORT"`
 
+	// AutoTargetLanguage selects the executable to instrument matching a Glob of chosen languages.
+	// To set this value via YAML, use discovery > instrument.
+	AutoTargetLanguage services.GlobAttr `env:"OTEL_EBPF_AUTO_TARGET_LANGUAGE,expand"`
+
 	// ServiceName is taken from either OTEL_EBPF_SERVICE_NAME env var or OTEL_SERVICE_NAME (for OTEL spec compatibility)
 	// Using env and envDefault is a trick to get the value either from one of either variables.
 	// Deprecated: Service name should be set in the instrumentation target (env vars, kube metadata...)
@@ -639,7 +643,7 @@ func (c *Config) Enabled(feature Feature) bool {
 	case FeatureNetO11y:
 		return c.NetworkFlows.Enable || c.promNetO11yEnabled() || c.otelNetO11yEnabled()
 	case FeatureAppO11y:
-		return c.Port.Len() > 0 || c.AutoTargetExe.IsSet() || len(c.Discovery.Instrument) > 0 ||
+		return c.Port.Len() > 0 || c.AutoTargetExe.IsSet() || c.AutoTargetLanguage.IsSet() || len(c.Discovery.Instrument) > 0 ||
 			c.Exec.IsSet() || len(c.Discovery.Services) > 0
 	}
 	return false

pkg/obi/config_test.go

@@ -508,6 +508,15 @@ func TestConfig_NetworkImplicitProm(t *testing.T) {
 	assert.True(t, cfg.Enabled(FeatureNetO11y)) // Net o11y should be on
 }
 
+func TestConfig_AutoLanguageEnv(t *testing.T) {
+	// OTEL_GO_AUTO_TARGET_EXE is an alias to OTEL_EBPF_AUTO_TARGET_EXE
+	// (Compatibility with OpenTelemetry)
+	t.Setenv("OTEL_EBPF_AUTO_TARGET_LANGUAGE", "{go,java}")
+	cfg, err := LoadConfig(bytes.NewReader(nil))
+	require.NoError(t, err)
+	assert.True(t, cfg.AutoTargetLanguage.MatchString("java"))
+}
+
 func TestConfig_ExternalLogger(t *testing.T) {
 	type testCase struct {
 		name          string