reporter: extract container.ID from cgroupv2 path

collector/internal/controller.go

@@ -37,9 +37,9 @@ func NewController(cfg *controller.Config,
 		ReportInterval:           intervals.ReportInterval(),
 		ExecutablesCacheElements: 16384,
 		// Next step: Calculate FramesCacheElements from numCores and samplingRate.
-		FramesCacheElements: 131072,
-		CGroupCacheElements: 1024,
-		SamplesPerSecond:    cfg.SamplesPerSecond,
+		FramesCacheElements:           131072,
+		PIDToContainerIDCacheElements: 1024,
+		SamplesPerSecond:              cfg.SamplesPerSecond,
 	}, nextConsumer)
 	if err != nil {
 		return nil, err

main.go

@@ -114,9 +114,9 @@ func mainWithExitCode() exitCode {
 		ReportInterval:           intervals.ReportInterval(),
 		ExecutablesCacheElements: 16384,
 		// Next step: Calculate FramesCacheElements from numCores and samplingRate.
-		FramesCacheElements: 131072,
-		CGroupCacheElements: 1024,
-		SamplesPerSecond:    cfg.SamplesPerSecond,
+		FramesCacheElements:           131072,
+		PIDToContainerIDCacheElements: 1024,
+		SamplesPerSecond:              cfg.SamplesPerSecond,
 	})
 	if err != nil {
 		log.Error(err)

reporter/base_reporter.go

@@ -7,6 +7,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"os"
 	"time"
 
 	lru "github.com/elastic/go-freelru"
@@ -34,8 +35,8 @@ type baseReporter struct {
 	// pdata holds the generator for the data being exported.
 	pdata *pdata.Pdata
 
-	// cgroupv2ID caches PID to container ID information for cgroupv2 containers.
-	cgroupv2ID *lru.SyncedLRU[libpf.PID, string]
+	// pidToContainerID caches PID to container ID for cgroupv2 containers.
+	pidToContainerID *lru.SyncedLRU[libpf.PID, string]
 
 	// traceEvents stores reported trace events (trace metadata with frames and counts)
 	traceEvents xsync.RWMutex[samples.TraceEventsTree]
@@ -96,9 +97,9 @@ func (b *baseReporter) ReportTraceEvent(trace *libpf.Trace, meta *samples.TraceE
 		extraMeta = b.cfg.ExtraSampleAttrProd.CollectExtraSampleMeta(trace, meta)
 	}
 
-	containerID, err := libpf.LookupCgroupv2(b.cgroupv2ID, meta.PID)
+	containerID, err := b.lookupContainerID(meta.PID)
 	if err != nil {
-		log.Debugf("Failed to get a cgroupv2 ID as container ID for PID %d: %v",
+		log.Debugf("Failed to get a container ID for PID %d: %v",
 			meta.PID, err)
 	}
 
@@ -164,3 +165,23 @@ func (b *baseReporter) FrameMetadata(args *FrameMetadataArgs) {
 	}
 	b.pdata.Frames.Add(args.FrameID, si)
 }
+
+// lookupContainerID extracts the container ID from a cgroup v2 path or
+// returns an empty string otherwise.
+func (b *baseReporter) lookupContainerID(pid libpf.PID) (string, error) {
+	if v, ok := b.pidToContainerID.GetAndRefresh(pid, 90*time.Second); ok {
+		return v, nil
+	}
+
+	// Slow path
+	pidCgroupFile, err := os.Open(fmt.Sprintf("/proc/%d/cgroup", pid))
+	if err != nil {
+		return "", err
+	}
+	defer pidCgroupFile.Close()
+
+	containerID := extractContainerID(pidCgroupFile)
+
+	b.pidToContainerID.Add(pid, containerID)
+	return containerID, nil
+}

reporter/collector_reporter.go

@@ -29,13 +29,13 @@ type CollectorReporter struct {
 
 // NewCollector builds a new CollectorReporter
 func NewCollector(cfg *Config, nextConsumer xconsumer.Profiles) (*CollectorReporter, error) {
-	cgroupv2ID, err := lru.NewSynced[libpf.PID, string](cfg.CGroupCacheElements,
+	pidToContainerID, err := lru.NewSynced[libpf.PID, string](cfg.PIDToContainerIDCacheElements,
 		func(pid libpf.PID) uint32 { return uint32(pid) })
 	if err != nil {
 		return nil, err
 	}
 	// Set a lifetime to reduce the risk of invalid data in case of PID reuse.
-	cgroupv2ID.SetLifetime(90 * time.Second)
+	pidToContainerID.SetLifetime(90 * time.Second)
 
 	// Next step: Dynamically configure the size of this LRU.
 	// Currently, we use the length of the JSON array in
@@ -59,13 +59,13 @@ func NewCollector(cfg *Config, nextConsumer xconsumer.Profiles) (*CollectorRepor
 
 	return &CollectorReporter{
 		baseReporter: &baseReporter{
-			cfg:          cfg,
-			name:         cfg.Name,
-			version:      cfg.Version,
-			pdata:        data,
-			cgroupv2ID:   cgroupv2ID,
-			traceEvents:  xsync.NewRWMutex(tree),
-			hostmetadata: hostmetadata,
+			cfg:              cfg,
+			name:             cfg.Name,
+			version:          cfg.Version,
+			pdata:            data,
+			pidToContainerID: pidToContainerID,
+			traceEvents:      xsync.NewRWMutex(tree),
+			hostmetadata:     hostmetadata,
 			runLoop: &runLoop{
 				stopSignal: make(chan libpf.Void),
 			},
@@ -85,7 +85,7 @@ func (r *CollectorReporter) Start(ctx context.Context) error {
 	}, func() {
 		// Allow the GC to purge expired entries to avoid memory leaks.
 		r.pdata.Purge()
-		r.cgroupv2ID.PurgeExpired()
+		r.pidToContainerID.PurgeExpired()
 	})
 
 	// When Stop() is called and a signal to 'stop' is received, then:

reporter/collector_reporter_test.go

@@ -52,9 +52,9 @@ func TestCollectorReporterReportTraceEvent(t *testing.T) {
 			}
 
 			r, err := NewCollector(&Config{
-				ExecutablesCacheElements: 1,
-				FramesCacheElements:      1,
-				CGroupCacheElements:      1,
+				ExecutablesCacheElements:      1,
+				FramesCacheElements:           1,
+				PIDToContainerIDCacheElements: 1,
 			}, next)
 			require.NoError(t, err)
 			if err := r.ReportTraceEvent(tt.trace, tt.meta); err != nil &&

reporter/config.go

@@ -30,8 +30,8 @@ type Config struct {
 	ExecutablesCacheElements uint32
 	// FramesCacheElements defines the item capacity of the frames cache.
 	FramesCacheElements uint32
-	// CGroupCacheElements defines the item capacity of the cgroup cache.
-	CGroupCacheElements uint32
+	// PIDToContainerIDCacheElements defines the item capacity of the pid cache.
+	PIDToContainerIDCacheElements uint32
 	// samplesPerSecond defines the number of samples per second.
 	SamplesPerSecond int
 

reporter/otlp_reporter.go

@@ -41,13 +41,13 @@ type OTLPReporter struct {
 
 // NewOTLP returns a new instance of OTLPReporter
 func NewOTLP(cfg *Config) (*OTLPReporter, error) {
-	cgroupv2ID, err := lru.NewSynced[libpf.PID, string](cfg.CGroupCacheElements,
+	pidToContainerID, err := lru.NewSynced[libpf.PID, string](cfg.PIDToContainerIDCacheElements,
 		func(pid libpf.PID) uint32 { return uint32(pid) })
 	if err != nil {
 		return nil, err
 	}
 	// Set a lifetime to reduce risk of invalid data in case of PID reuse.
-	cgroupv2ID.SetLifetime(90 * time.Second)
+	pidToContainerID.SetLifetime(90 * time.Second)
 
 	// Next step: Dynamically configure the size of this LRU.
 	// Currently, we use the length of the JSON array in
@@ -71,13 +71,13 @@ func NewOTLP(cfg *Config) (*OTLPReporter, error) {
 
 	return &OTLPReporter{
 		baseReporter: &baseReporter{
-			cfg:          cfg,
-			name:         cfg.Name,
-			version:      cfg.Version,
-			pdata:        data,
-			cgroupv2ID:   cgroupv2ID,
-			traceEvents:  xsync.NewRWMutex(eventsTree),
-			hostmetadata: hostmetadata,
+			cfg:              cfg,
+			name:             cfg.Name,
+			version:          cfg.Version,
+			pdata:            data,
+			pidToContainerID: pidToContainerID,
+			traceEvents:      xsync.NewRWMutex(eventsTree),
+			hostmetadata:     hostmetadata,
 			runLoop: &runLoop{
 				stopSignal: make(chan libpf.Void),
 			},
@@ -110,7 +110,7 @@ func (r *OTLPReporter) Start(ctx context.Context) error {
 	}, func() {
 		// Allow the GC to purge expired entries to avoid memory leaks.
 		r.pdata.Purge()
-		r.cgroupv2ID.PurgeExpired()
+		r.pidToContainerID.PurgeExpired()
 	})
 
 	// When Stop() is called and a signal to 'stop' is received, then:

reporter/util.go

@@ -3,11 +3,47 @@
 
 package reporter // import "go.opentelemetry.io/ebpf-profiler/reporter"
 
-import "github.com/zeebo/xxh3"
+import (
+	"bufio"
+	"io"
+	"regexp"
+
+	log "github.com/sirupsen/logrus"
+	"github.com/zeebo/xxh3"
+)
+
+//nolint:lll
+var (
+	cgroupv2ContainerIDPattern = regexp.MustCompile(`0:.*?:.*?([0-9a-fA-F]{64})(?:\.scope)?(?:/[a-z]+)?$`)
+)
 
 // hashString is a helper function for LRUs that use string as a key.
 // Xxh3 turned out to be the fastest hash function for strings in the FreeLRU benchmarks.
 // It was only outperformed by the AES hash function, which is implemented in Plan9 assembly.
 func hashString(s string) uint32 {
 	return uint32(xxh3.HashString(s))
 }
+
+// extractContainerID returns the containerID for pid if cgroup v2 is used.
+func extractContainerID(pidCgroupFile io.Reader) string {
+	scanner := bufio.NewScanner(pidCgroupFile)
+	buf := make([]byte, 512)
+	// Providing a predefined buffer overrides the internal buffer that Scanner uses (4096 bytes).
+	// We can do that and also set a maximum allocation size on the following call.
+	// With a maximum of 4096 characters path in the kernel, 8192 should be fine here. We don't
+	// expect lines in /proc/<PID>/cgroup to be longer than that.
+	scanner.Buffer(buf, 8192)
+	var pathParts []string
+	for scanner.Scan() {
+		line := scanner.Text()
+		pathParts = cgroupv2ContainerIDPattern.FindStringSubmatch(line)
+		if pathParts == nil {
+			log.Debugf("Could not extract cgroupv2 path from line: %s", line)
+			continue
+		}
+		return pathParts[1]
+	}
+
+	// No container ID could be extracted
+	return ""
+}

reporter/util_test.go

@@ -0,0 +1,56 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package reporter // import "go.opentelemetry.io/ebpf-profiler/reporter"
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+//nolint:lll
+func TestExtractContainerID(t *testing.T) {
+	tests := []struct {
+		line                string
+		expectedContainerID string
+	}{
+		{
+			line:                "0::/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-podf6f2d169_f2ae_4afa-95ed_06ff2ed6b288.slice/cri-containerd-b4d6d161c62525d726fa394b27df30e14f8ea5646313ada576b390de70cfc8cc.scope",
+			expectedContainerID: "b4d6d161c62525d726fa394b27df30e14f8ea5646313ada576b390de70cfc8cc",
+		},
+		{
+			line:                "0::/kubepods/besteffort/pod05e102bf-8744-4942-a241-9b6f07983a53/f52a212505a606972cf8614c3cb856539e71b77ecae33436c5ac442232fbacf8",
+			expectedContainerID: "f52a212505a606972cf8614c3cb856539e71b77ecae33436c5ac442232fbacf8",
+		},
+		{
+			line:                "0::/kubepods/besteffort/pod897277d4-5e6f-4999-a976-b8340e8d075e/crio-a4d6b686848a610472a2eed3ae20d4d64b6b4819feb9fdfc7fd7854deaf59ef3",
+			expectedContainerID: "a4d6b686848a610472a2eed3ae20d4d64b6b4819feb9fdfc7fd7854deaf59ef3",
+		},
+		{
+			line:                "0::/kubepods.slice/kubepods-besteffort.slice/kubepods-besteffort-pod4c9f1974_5c46_44c2_b42f_3bbf0e98eef9.slice/cri-containerd-bacb920470900725e0aa7d914fee5eb0854315448b024b6b8420ad8429c607ba.scope",
+			expectedContainerID: "bacb920470900725e0aa7d914fee5eb0854315448b024b6b8420ad8429c607ba",
+		},
+		{
+			line: "0::/user.slice/user-1000.slice/user@1000.service/app.slice/app-org.gnome.Terminal.slice/vte-spawn-868f9513-eee8-457d-8e36-1b37ae8ae622.scope",
+		},
+		{
+			line: "0::/../../user.slice/user-501.slice/session-3.scope",
+		},
+		{
+			line:                "0::/system.slice/docker-b1eba9dfaeba29d8b80532a574a03ea3cac29384327f339c26da13649e2120df.scope/init",
+			expectedContainerID: "b1eba9dfaeba29d8b80532a574a03ea3cac29384327f339c26da13649e2120df",
+		},
+	}
+
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.expectedContainerID, func(t *testing.T) {
+			reader := bytes.NewReader([]byte(tc.line))
+
+			gotContainerID := extractContainerID(reader)
+			assert.Equal(t, tc.expectedContainerID, gotContainerID)
+		})
+	}
+}