Add container id support to Resource (open-telemetry#2418)

* Add container id support to Resource

* Fix wrong test case name

* Add WithContainer option

* Update CHANGELOG

* Fix comments

* Update CHANGELOG

* Use regex to find container id

* Add tests for reading cgroup file

* Update sdk/resource/container.go

Co-authored-by: Chester Cheung <cheung.zhy.csu@gmail.com>

* Update format

Co-authored-by: Chester Cheung <cheung.zhy.csu@gmail.com>
Co-authored-by: Anthony Mirabella <a9@aneurysm9.com>

CHANGELOG.md

@@ -26,6 +26,7 @@ This update is a breaking change of the unstable Metrics API. Code instrumented
 
   If the provided environment variables are invalid (negative), the default values would be used.
 - Rename the `gc` runtime name to `go` (#2560)
+- Add container id support to Resource. (#2418)
 - Add span attribute value length limit.
   The new `AttributeValueLengthLimit` field is added to the `"go.opentelemetry.io/otel/sdk/trace".SpanLimits` type to configure this limit for a `TracerProvider`.
   The default limit for this resource is "unlimited". (#2637)

sdk/resource/config.go

@@ -171,3 +171,16 @@ func WithProcessRuntimeVersion() Option {
 func WithProcessRuntimeDescription() Option {
 	return WithDetectors(processRuntimeDescriptionDetector{})
 }
+
+// WithContainer adds all the Container attributes to the configured Resource.
+// See individual WithContainer* functions to configure specific attributes.
+func WithContainer() Option {
+	return WithDetectors(
+		cgroupContainerIDDetector{},
+	)
+}
+
+// WithContainerID adds an attribute with the id of the container to the configured Resource.
+func WithContainerID() Option {
+	return WithDetectors(cgroupContainerIDDetector{})
+}

sdk/resource/container.go

@@ -0,0 +1,100 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package resource // import "go.opentelemetry.io/otel/sdk/resource"
+
+import (
+	"bufio"
+	"context"
+	"errors"
+	"io"
+	"os"
+	"regexp"
+
+	semconv "go.opentelemetry.io/otel/semconv/v1.7.0"
+)
+
+type containerIDProvider func() (string, error)
+
+var (
+	containerID         containerIDProvider = getContainerIDFromCGroup
+	cgroupContainerIDRe                     = regexp.MustCompile(`^.*/(?:.*-)?([0-9a-f]+)(?:\.|\s*$)`)
+)
+
+type cgroupContainerIDDetector struct{}
+
+const cgroupPath = "/proc/self/cgroup"
+
+// Detect returns a *Resource that describes the id of the container.
+// If no container id found, an empty resource will be returned.
+func (cgroupContainerIDDetector) Detect(ctx context.Context) (*Resource, error) {
+	containerID, err := containerID()
+	if err != nil {
+		return nil, err
+	}
+
+	if containerID == "" {
+		return Empty(), nil
+	}
+	return NewWithAttributes(semconv.SchemaURL, semconv.ContainerIDKey.String(containerID)), nil
+}
+
+var (
+	defaultOSStat = os.Stat
+	osStat        = defaultOSStat
+
+	defaultOSOpen = func(name string) (io.ReadCloser, error) {
+		return os.Open(name)
+	}
+	osOpen = defaultOSOpen
+)
+
+// getContainerIDFromCGroup returns the id of the container from the cgroup file.
+// If no container id found, an empty string will be returned.
+func getContainerIDFromCGroup() (string, error) {
+	if _, err := osStat(cgroupPath); errors.Is(err, os.ErrNotExist) {
+		// File does not exist, skip
+		return "", nil
+	}
+
+	file, err := osOpen(cgroupPath)
+	if err != nil {
+		return "", err
+	}
+	defer file.Close()
+
+	return getContainerIDFromReader(file), nil
+}
+
+// getContainerIDFromReader returns the id of the container from reader.
+func getContainerIDFromReader(reader io.Reader) string {
+	scanner := bufio.NewScanner(reader)
+	for scanner.Scan() {
+		line := scanner.Text()
+
+		if id := getContainerIDFromLine(line); id != "" {
+			return id
+		}
+	}
+	return ""
+}
+
+// getContainerIDFromLine returns the id of the container from one string line.
+func getContainerIDFromLine(line string) string {
+	matches := cgroupContainerIDRe.FindStringSubmatch(line)
+	if len(matches) <= 1 {
+		return ""
+	}
+	return matches[1]
+}

sdk/resource/container_test.go

@@ -0,0 +1,169 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package resource
+
+import (
+	"errors"
+	"io"
+	"os"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func setDefaultContainerProviders() {
+	setContainerProviders(
+		getContainerIDFromCGroup,
+	)
+}
+
+func setContainerProviders(
+	idProvider containerIDProvider,
+) {
+	containerID = idProvider
+}
+
+func TestGetContainerIDFromLine(t *testing.T) {
+	testCases := []struct {
+		name                string
+		line                string
+		expectedContainerID string
+	}{
+		{
+			name:                "with suffix",
+			line:                "13:name=systemd:/podruntime/docker/kubepods/ac679f8a8319c8cf7d38e1adf263bc08d23.aaaa",
+			expectedContainerID: "ac679f8a8319c8cf7d38e1adf263bc08d23",
+		},
+		{
+			name:                "with prefix and suffix",
+			line:                "13:name=systemd:/podruntime/docker/kubepods/crio-dc679f8a8319c8cf7d38e1adf263bc08d23.stuff",
+			expectedContainerID: "dc679f8a8319c8cf7d38e1adf263bc08d23",
+		},
+		{
+			name:                "no prefix and suffix",
+			line:                "13:name=systemd:/pod/d86d75589bf6cc254f3e2cc29debdf85dde404998aa128997a819ff991827356",
+			expectedContainerID: "d86d75589bf6cc254f3e2cc29debdf85dde404998aa128997a819ff991827356",
+		},
+		{
+			name:                "with space",
+			line:                " 13:name=systemd:/pod/d86d75589bf6cc254f3e2cc29debdf85dde404998aa128997a819ff991827356 ",
+			expectedContainerID: "d86d75589bf6cc254f3e2cc29debdf85dde404998aa128997a819ff991827356",
+		},
+		{
+			name: "invalid hex string",
+			line: "13:name=systemd:/podruntime/docker/kubepods/ac679f8a8319c8cf7d38e1adf263bc08d23zzzz",
+		},
+		{
+			name: "no container id - 1",
+			line: "pids: /",
+		},
+		{
+			name: "no container id - 2",
+			line: "pids: ",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			containerID := getContainerIDFromLine(tc.line)
+			assert.Equal(t, tc.expectedContainerID, containerID)
+		})
+	}
+}
+
+func TestGetContainerIDFromReader(t *testing.T) {
+	testCases := []struct {
+		name                string
+		reader              io.Reader
+		expectedContainerID string
+	}{
+		{
+			name: "multiple lines",
+			reader: strings.NewReader(`//
+1:name=systemd:/podruntime/docker/kubepods/docker-dc579f8a8319c8cf7d38e1adf263bc08d23
+1:name=systemd:/podruntime/docker/kubepods/docker-dc579f8a8319c8cf7d38e1adf263bc08d24
+`),
+			expectedContainerID: "dc579f8a8319c8cf7d38e1adf263bc08d23",
+		},
+		{
+			name: "no container id",
+			reader: strings.NewReader(`//
+1:name=systemd:/podruntime/docker
+`),
+			expectedContainerID: "",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			containerID := getContainerIDFromReader(tc.reader)
+			assert.Equal(t, tc.expectedContainerID, containerID)
+		})
+	}
+}
+
+func TestGetContainerIDFromCGroup(t *testing.T) {
+	t.Cleanup(func() {
+		osStat = defaultOSStat
+		osOpen = defaultOSOpen
+	})
+
+	testCases := []struct {
+		name                string
+		cgroupFileNotExist  bool
+		openFileError       error
+		content             string
+		expectedContainerID string
+		expectedError       bool
+	}{
+		{
+			name:               "the cgroup file does not exist",
+			cgroupFileNotExist: true,
+		},
+		{
+			name:          "error when opening cgroup file",
+			openFileError: errors.New("test"),
+			expectedError: true,
+		},
+		{
+			name:                "cgroup file",
+			content:             "1:name=systemd:/podruntime/docker/kubepods/docker-dc579f8a8319c8cf7d38e1adf263bc08d23",
+			expectedContainerID: "dc579f8a8319c8cf7d38e1adf263bc08d23",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			osStat = func(name string) (os.FileInfo, error) {
+				if tc.cgroupFileNotExist {
+					return nil, os.ErrNotExist
+				}
+				return nil, nil
+			}
+
+			osOpen = func(name string) (io.ReadCloser, error) {
+				if tc.openFileError != nil {
+					return nil, tc.openFileError
+				}
+				return io.NopCloser(strings.NewReader(tc.content)), nil
+			}
+
+			containerID, err := getContainerIDFromCGroup()
+			assert.Equal(t, tc.expectedError, err != nil)
+			assert.Equal(t, tc.expectedContainerID, containerID)
+		})
+	}
+}

sdk/resource/export_test.go

@@ -23,6 +23,8 @@ var (
 	SetUserProviders                = setUserProviders
 	SetDefaultOSDescriptionProvider = setDefaultOSDescriptionProvider
 	SetOSDescriptionProvider        = setOSDescriptionProvider
+	SetDefaultContainerProviders    = setDefaultContainerProviders
+	SetContainerProviders           = setContainerProviders
 )
 
 var (

sdk/resource/process_test.go

@@ -102,13 +102,14 @@ func restoreAttributesProviders() {
 	resource.SetDefaultRuntimeProviders()
 	resource.SetDefaultUserProviders()
 	resource.SetDefaultOSDescriptionProvider()
+	resource.SetDefaultContainerProviders()
 }
 
 func TestWithProcessFuncsErrors(t *testing.T) {
 	mockProcessAttributesProvidersWithErrors()
 
-	t.Run("WithPID", testWithProcessExecutablePathError)
-	t.Run("WithExecutableName", testWithProcessOwnerError)
+	t.Run("WithExecutablePath", testWithProcessExecutablePathError)
+	t.Run("WithOwner", testWithProcessOwnerError)
 
 	restoreAttributesProviders()
 }

sdk/resource/resource_test.go

@@ -649,3 +649,74 @@ func hostname() string {
 	}
 	return hn
 }
+
+func TestWithContainerID(t *testing.T) {
+	t.Cleanup(restoreAttributesProviders)
+
+	fakeContainerID := "fake-container-id"
+
+	testCases := []struct {
+		name                string
+		containerIDProvider func() (string, error)
+		expectedResource    map[string]string
+		expectedErr         bool
+	}{
+		{
+			name: "get container id",
+			containerIDProvider: func() (string, error) {
+				return fakeContainerID, nil
+			},
+			expectedResource: map[string]string{
+				string(semconv.ContainerIDKey): fakeContainerID,
+			},
+		},
+		{
+			name: "no container id found",
+			containerIDProvider: func() (string, error) {
+				return "", nil
+			},
+			expectedResource: map[string]string{},
+		},
+		{
+			name: "error",
+			containerIDProvider: func() (string, error) {
+				return "", fmt.Errorf("unable to get container id")
+			},
+			expectedResource: map[string]string{},
+			expectedErr:      true,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			resource.SetContainerProviders(tc.containerIDProvider)
+
+			res, err := resource.New(context.Background(),
+				resource.WithContainerID(),
+			)
+
+			if tc.expectedErr {
+				assert.Error(t, err)
+			}
+			assert.Equal(t, tc.expectedResource, toMap(res))
+		})
+	}
+}
+
+func TestWithContainer(t *testing.T) {
+	t.Cleanup(restoreAttributesProviders)
+
+	fakeContainerID := "fake-container-id"
+	resource.SetContainerProviders(func() (string, error) {
+		return fakeContainerID, nil
+	})
+
+	res, err := resource.New(context.Background(),
+		resource.WithContainer(),
+	)
+
+	assert.NoError(t, err)
+	assert.Equal(t, map[string]string{
+		string(semconv.ContainerIDKey): fakeContainerID,
+	}, toMap(res))
+}