feat: enable namespace PID translation

- Add simple test checking struct offset computation used by namespace pid
  translation.
- Tracer initialization fails if BTF is not available but namespace PID
  translation is enabled.

Author: 7za

tracer/ebpf_integration_test.go

@@ -6,6 +6,7 @@
 package tracer_test
 
 import (
+	"fmt"
 	"math"
 	"runtime"
 	"slices"
@@ -186,16 +187,32 @@ Loop:
 }
 
 func TestAllTracers(t *testing.T) {
-	tr, err := tracer.NewTracer(t.Context(), &tracer.Config{
-		Intervals:              &mockIntervals{},
-		IncludeTracers:         tracertypes.AllTracers(),
-		SamplesPerSecond:       20,
-		ProbabilisticInterval:  100,
-		ProbabilisticThreshold: 100,
-		OffCPUThreshold:        uint32(math.MaxUint32 / 100),
-		VerboseMode:            true,
-		LoadProbe:              true,
-	})
-	require.NoError(t, err)
-	defer tr.Close()
+	testcases := []struct {
+		enablePidTranslation bool
+	}{
+		{
+			enablePidTranslation: true,
+		},
+		{
+			enablePidTranslation: false,
+		},
+	}
+
+	for _, testcase := range testcases {
+		t.Run(fmt.Sprintf("enablePidTranslation=%t", testcase.enablePidTranslation), func(t *testing.T) {
+			tr, err := tracer.NewTracer(t.Context(), &tracer.Config{
+				Intervals:              &mockIntervals{},
+				IncludeTracers:         tracertypes.AllTracers(),
+				SamplesPerSecond:       20,
+				ProbabilisticInterval:  100,
+				ProbabilisticThreshold: 100,
+				OffCPUThreshold:        uint32(math.MaxUint32 / 100),
+				VerboseMode:            true,
+				LoadProbe:              true,
+				EnableNamespacePID:     testcase.enablePidTranslation,
+			})
+			require.NoError(t, err)
+			defer tr.Close()
+		})
+	}
 }

tracer/systemconfig.go

@@ -402,12 +402,14 @@ func determineSysConfig(coll *cebpf.CollectionSpec, maps map[string]*cebpf.Map,
 		if err := parseBTF(vars, spec); err != nil {
 			btfResolution = false
 		}
-		// parseBTFForNsTranslation is only called if
-		// namespace PID translation is enabled and BTF resolution is successful.
-		if enableNamespacePID && btfResolution {
-			err := parseBTFForNsTranslation(vars, spec)
-			log.Debugf("parseBTFForNsTranslation err %v", err)
-			log.Debugf("vars.ns_translation_enabled %+v", vars)
+	}
+
+	if enableNamespacePID {
+		if !btfResolution {
+			return fmt.Errorf("configuration error: namespace PID translation is enabled but BTF resolution is not available")
+		}
+		if err := parseBTFForNsTranslation(vars, spec); err != nil {
+			return err
 		}
 	}
 

tracer/systemconfig_test.go

@@ -0,0 +1,50 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package tracer
+
+import (
+	"os"
+	"runtime"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestGetCurrentNS_FileNotFound(t *testing.T) {
+	_, _, err := getCurrentNS("/nonexistent/path/pid")
+	require.Error(t, err)
+	require.True(t, os.IsNotExist(err))
+}
+
+func TestGetCurrentNS_ProcSelfNsPid(t *testing.T) {
+	if runtime.GOOS != "linux" {
+		t.Skipf("skipping: /proc/self/ns/pid is Linux-specific (GOOS=%s)", runtime.GOOS)
+	}
+	const procSelfNsPid = "/proc/self/ns/pid"
+	if _, err := os.Stat(procSelfNsPid); err != nil {
+		t.Skipf("skipping: %s not available: %v", procSelfNsPid, err)
+	}
+	_, ino, err := getCurrentNS(procSelfNsPid)
+	require.NoError(t, err)
+	require.NotZero(t, ino, "pid namespace inode should be non-zero")
+}
+
+// TestParseBTFForNsTranslation verifies that namespace PID translation offsets
+// can be resolved from kernel BTF when available. Skips when BTF is not present.
+func TestParseBTFForNsTranslation(t *testing.T) {
+	if runtime.GOARCH != "amd64" && runtime.GOARCH != "arm64" {
+		t.Skipf("skipping: unsupported GOARCH=%s", runtime.GOARCH)
+	}
+	spec, err := loadBTFSpec()
+	if err != nil {
+		t.Skipf("skipping: kernel BTF not available: %v", err)
+	}
+	var vars sysConfigVars
+	err = parseBTFForNsTranslation(&vars, spec)
+	require.NoError(t, err)
+	require.True(t, vars.ns_translation_enabled)
+	require.Greater(t, vars.task_stack_offset, uint32(0))
+	require.Greater(t, vars.task_nsproxy_off, uint32(0))
+	require.Greater(t, vars.upid_size, uint32(0))
+}