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identity.go
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identity.go
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// Copyright 2022 SAP SE or an SAP affiliate company. All rights reserved. This file is licensed under the Apache Software License, v. 2 except as noted otherwise in the LICENSE file
//
// 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 gardener
import (
"bufio"
"fmt"
"os"
"regexp"
"strings"
"k8s.io/component-base/version"
gardencorev1beta1 "github.com/gardener/gardener/pkg/apis/core/v1beta1"
"github.com/gardener/gardener/pkg/utils"
)
// DetermineIdentity determines the Gardener component identity.
// We want to determine the Docker container id of the currently running instance because we need to identify for still
// ongoing operations whether another instance is still operating the respective Shoots. When running locally, we
// generate a random string because there is no container id.
func DetermineIdentity() (*gardencorev1beta1.Gardener, error) {
var (
validID = regexp.MustCompile(`([0-9a-f]{64})`)
id string
name string
err error
)
name, err = os.Hostname()
if err != nil {
return nil, fmt.Errorf("unable to get hostname: %w", err)
}
// If running inside a Kubernetes cluster (as container) we can read the container id from the proc file system.
// Otherwise generate a random string for the id
if cGroupFile, err := os.Open("/proc/self/cgroup"); err == nil {
defer cGroupFile.Close()
reader := bufio.NewReader(cGroupFile)
var cgroupV1 string
for {
line, err := reader.ReadString('\n')
if err != nil {
break
}
// Store cgroup-v1 result for fall back
if strings.HasPrefix(line, "1:name=systemd") {
cgroupV1 = line
}
// Always prefer cgroup-v2
if strings.HasPrefix(line, "0::") {
if containerID := extractID(line); validID.MatchString(containerID) {
id = containerID
break
}
}
}
// Fall-back to cgroup-v1 if possible
if len(id) == 0 && len(cgroupV1) > 0 {
id = extractID(cgroupV1)
}
}
if id == "" {
id, err = utils.GenerateRandomString(64)
if err != nil {
return nil, fmt.Errorf("unable to generate id: %w", err)
}
}
return &gardencorev1beta1.Gardener{
ID: id,
Name: name,
Version: version.Get().GitVersion,
}, nil
}
func extractID(line string) string {
var (
id string
splitBySlash = strings.Split(line, "/")
)
if len(splitBySlash) == 0 {
return ""
}
id = strings.TrimSpace(splitBySlash[len(splitBySlash)-1])
id = strings.TrimSuffix(id, ".scope")
id = strings.TrimPrefix(id, "docker-")
return id
}