Prevent beyla self-instrumentation

pkg/internal/discover/attacher.go

@@ -3,6 +3,7 @@ package discover
 import (
 	"context"
 	"log/slog"
+	"os"
 	"path"
 
 	"github.com/cilium/ebpf/link"
@@ -27,6 +28,7 @@ type TraceAttacher struct {
 	DeleteTracers     chan *Instrumentable
 	Metrics           imetrics.Reporter
 	pinPath           string
+	beylaPID          int
 
 	// processInstances keeps track of the instances of each process. This will help making sure
 	// that we don't remove the BPF resources of an executable until all their instances are removed
@@ -46,6 +48,7 @@ func (ta *TraceAttacher) attacherLoop() (pipe.FinalFunc[[]Event[Instrumentable]]
 	ta.log = slog.With("component", "discover.TraceAttacher")
 	ta.existingTracers = map[uint64]*ebpf.ProcessTracer{}
 	ta.processInstances = maps.MultiCounter[uint64]{}
+	ta.beylaPID = os.Getpid()
 	ta.pinPath = BuildPinPath(ta.Cfg)
 
 	if err := ta.init(); err != nil {
@@ -79,6 +82,10 @@ func (ta *TraceAttacher) attacherLoop() (pipe.FinalFunc[[]Event[Instrumentable]]
 	}, nil
 }
 
+func (ta *TraceAttacher) skipSelfInstrumentation(ie *Instrumentable) bool {
+	return ie.FileInfo.Pid == int32(ta.beylaPID) && !ta.Cfg.Discovery.AllowSelfInstrumentation
+}
+
 //nolint:cyclop
 func (ta *TraceAttacher) getTracer(ie *Instrumentable) (*ebpf.ProcessTracer, bool) {
 	if tracer, ok := ta.existingTracers[ie.FileInfo.Ino]; ok {
@@ -96,6 +103,12 @@ func (ta *TraceAttacher) getTracer(ie *Instrumentable) (*ebpf.ProcessTracer, boo
 		ta.log.Debug(".done")
 		return nil, false
 	}
+
+	if ta.skipSelfInstrumentation(ie) {
+		ta.log.Info("skipping self-instrumentation of Beyla process", "cmd", ie.FileInfo.CmdExePath, "pid", ie.FileInfo.Pid)
+		return nil, false
+	}
+
 	ta.log.Info("instrumenting process", "cmd", ie.FileInfo.CmdExePath, "pid", ie.FileInfo.Pid)
 	ta.Metrics.InstrumentProcess(ie.FileInfo.ExecutableName())
 

pkg/internal/discover/attacher_test.go

@@ -0,0 +1,57 @@
+package discover
+
+import (
+	"log/slog"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/grafana/beyla/pkg/beyla"
+	"github.com/grafana/beyla/pkg/internal/exec"
+	"github.com/grafana/beyla/pkg/services"
+)
+
+func TestSkipSelfInstrumentation(t *testing.T) {
+	pid := os.Getpid()
+
+	for _, tt := range []struct {
+		ta     *TraceAttacher
+		isSelf bool
+		test   string
+	}{
+		{
+			ta: &TraceAttacher{
+				log:      slog.With("component", "discover.TraceAttacher"),
+				Cfg:      &beyla.DefaultConfig,
+				beylaPID: pid,
+			},
+			isSelf: true,
+			test:   "Default config",
+		},
+		{
+			ta: &TraceAttacher{
+				log:      slog.With("component", "discover.TraceAttacher"),
+				Cfg:      &beyla.DefaultConfig,
+				beylaPID: 0,
+			},
+			isSelf: false,
+			test:   "Default config, non-beyla pid",
+		},
+		{
+			ta: &TraceAttacher{
+				log:      slog.With("component", "discover.TraceAttacher"),
+				Cfg:      &beyla.Config{Discovery: services.DiscoveryConfig{AllowSelfInstrumentation: true}},
+				beylaPID: pid,
+			},
+			isSelf: false,
+			test:   "Beyla pid, allow self instrumentation",
+		},
+	} {
+		t.Run(tt.test, func(t *testing.T) {
+			i := Instrumentable{FileInfo: &exec.FileInfo{Pid: int32(pid)}}
+
+			assert.Equal(t, tt.isSelf, tt.ta.skipSelfInstrumentation(&i))
+		})
+	}
+}

pkg/services/criteria.go

@@ -56,6 +56,8 @@ type DiscoveryConfig struct {
 	// gathered for certain languages, such as Golang.
 	SystemWide bool `yaml:"system_wide" env:"BEYLA_SYSTEM_WIDE"`
 
+	AllowSelfInstrumentation bool `yaml:"allow_self_instrumentation" env:"BEYLA_ALLOW_SELF_INSTRUMENTATION"`
+
 	// This can be enabled to use generic HTTP tracers only, no Go-specifics will be used:
 	SkipGoSpecificTracers bool `yaml:"skip_go_specific_tracers" env:"BEYLA_SKIP_GO_SPECIFIC_TRACERS"`
 

test/integration/red_test.go

@@ -685,3 +685,14 @@ func testPrometheusBeylaBuildInfo(t *testing.T) {
 		require.NotEmpty(t, results)
 	})
 }
+
+func testPrometheusNoBeylaEvents(t *testing.T) {
+	pq := prom.Client{HostPort: prometheusHostPort}
+	var results []prom.Result
+	test.Eventually(t, testTimeout, func(t require.TestingT) {
+		var err error
+		results, err = pq.Query(`http_server_request_duration_seconds_count{service_name="beyla"}`)
+		require.NoError(t, err)
+		require.Equal(t, 0, len(results))
+	})
+}

test/integration/suites_test.go

@@ -219,6 +219,8 @@ func TestSuite_PrometheusScrape(t *testing.T) {
 	compose.Env = append(compose.Env,
 		`INSTRUMENTER_CONFIG_SUFFIX=-promscrape`,
 		`PROM_CONFIG_SUFFIX=-promscrape`,
+		`BEYLA_EXECUTABLE_NAME=`,
+		`BEYLA_OPEN_PORT=8082,8999`, // force Beyla self-instrumentation to ensure we don't do it
 	)
 
 	require.NoError(t, err)
@@ -227,6 +229,7 @@ func TestSuite_PrometheusScrape(t *testing.T) {
 	t.Run("GRPC RED metrics", testREDMetricsGRPC)
 	t.Run("Internal Prometheus metrics", testInternalPrometheusExport)
 	t.Run("Testing Beyla Build Info metric", testPrometheusBeylaBuildInfo)
+	t.Run("Testing for no Beyla self metrics", testPrometheusNoBeylaEvents)
 	t.Run("Testing process-level metrics", testProcesses(map[string]string{
 		"process_executable_name": "testserver",
 		"process_executable_path": "/testserver",