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// 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/v1.17.0"
)
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.ContainerID(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]
}
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