Kubelet v1.25.x源码——SecretManager

1. 环境说明

Kubernetes源码版本：remotes/origin/release-1.25
Kubernetes编译出来的Kubelet版本：Kubernetes v1.24.0-beta.0.2463+ee7799bab469d7
Kubernetes集群实验环境：使用Kubernetes v1.25.4二进制的方式搭建了一个单节点集群

K8S 单节点单节点搭建可以参考：Kubernetes v1.25 搭建单节点集群用于Debug K8S源码

Golang版本：go1.19.3 linux/amd64
IDEA版本：2022.2.3
Delve版本：1.9.1

[root@k8s-master1 kubernetes]#
[root@k8s-master1 kubernetes]# dlv version
Delve Debugger
Version: 1.9.1
Build: $Id: d81b9fd12bfa603f3cf7a4bc842398bd61c42940 $
[root@k8s-master1 kubernetes]#
[root@k8s-master1 kubernetes]# go version
go version go1.19.3 linux/amd64
[root@k8s-master1 kubernetes]#
[root@k8s-master1 kubernetes]# kubectl version
WARNING: This version information is deprecated and will be replaced with the output from kubectl version --short.  Use --output=yaml|json to get the full version.
Client Version: version.Info{Major:"1", Minor:"25", GitVersion:"v1.25.4", GitCommit:"872a965c6c6526caa949f0c6ac028ef7aff3fb78", GitTreeState:"clean", BuildDate:"2022-11-09T13:36:36Z", GoVersion:"go1.19.3", Compiler:"gc", Platform:"linux/amd64"}
Kustomize Version: v4.5.7
Server Version: version.Info{Major:"1", Minor:"25", GitVersion:"v1.25.4", GitCommit:"872a965c6c6526caa949f0c6ac028ef7aff3fb78", GitTreeState:"clean", BuildDate:"2022-11-09T13:29:58Z", GoVersion:"go1.19.3", Compiler:"gc", Platform:"linux/amd64"}
[root@k8s-master1 kubernetes]#
[root@k8s-master1 kubernetes]#
[root@k8s-master1 kubernetes]# kubectl get nodes -owide
NAME          STATUS   ROLES    AGE   VERSION   INTERNAL-IP     EXTERNAL-IP   OS-IMAGE                KERNEL-VERSION                CONTAINER-RUNTIME
k8s-master1   Ready    <none>   31h   v1.25.4   192.168.11.71   <none>        CentOS Linux 7 (Core)   3.10.0-1160.80.1.el7.x86_64   containerd://1.6.10
[root@k8s-master1 kubernetes]#
[root@k8s-master1 kubernetes]#
[root@k8s-master1 kubernetes]# kubectl get componentstatus
Warning: v1 ComponentStatus is deprecated in v1.19+
NAME                 STATUS    MESSAGE                         ERROR
etcd-0               Healthy   {"health":"true","reason":""}
controller-manager   Healthy   ok
scheduler            Healthy   ok
[root@k8s-master1 kubernetes]#

Kubelet启动参数配置如下：

[root@k8s-master1 kubernetes]# ps -ef|grep "/usr/local/bin/kubelet"
root       7972      1  6 07:06 ?        00:00:06 /usr/local/bin/kubelet --bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.kubeconfig --kubeconfig=/etc/kubernetes/kubelet.kubeconfig --config=/etc/kubernetes/kubelet-conf.yml --container-runtime-endpoint=unix:///run/containerd/containerd.sock --node-labels=node.kubernetes.io/node= --v=8
root       9549   6424  0 07:07 pts/0    00:00:00 grep --color=auto /usr/local/bin/kubelet
[root@k8s-master1 kubernetes]#

Kubelet参数配置如下：

apiVersion: kubelet.config.k8s.io/v1beta1
kind: KubeletConfiguration
address: 0.0.0.0
port: 10250
readOnlyPort: 10255
authentication:
  anonymous:
    enabled: false
  webhook:
    cacheTTL: 2m0s
    enabled: true
  x509:
    clientCAFile: /etc/kubernetes/pki/ca.pem
authorization:
  mode: Webhook
  webhook:
    cacheAuthorizedTTL: 5m0s
    cacheUnauthorizedTTL: 30s
cgroupDriver: systemd
cgroupsPerQOS: true
clusterDNS:
- 10.96.0.10
clusterDomain: cluster.local
containerLogMaxFiles: 5
containerLogMaxSize: 10Mi
contentType: application/vnd.kubernetes.protobuf
cpuCFSQuota: true
cpuManagerPolicy: none
cpuManagerReconcilePeriod: 10s
enableControllerAttachDetach: true
enableDebuggingHandlers: true
enforceNodeAllocatable:
- pods
eventBurst: 10
eventRecordQPS: 5
evictionHard:
  imagefs.available: 15%
  memory.available: 100Mi
  nodefs.available: 10%
  nodefs.inodesFree: 5%
evictionPressureTransitionPeriod: 5m0s
failSwapOn: true
fileCheckFrequency: 20s
hairpinMode: promiscuous-bridge
healthzBindAddress: 127.0.0.1
healthzPort: 10248
httpCheckFrequency: 20s
imageGCHighThresholdPercent: 85
imageGCLowThresholdPercent: 80
imageMinimumGCAge: 2m0s
iptablesDropBit: 15
iptablesMasqueradeBit: 14
kubeAPIBurst: 10
kubeAPIQPS: 5
makeIPTablesUtilChains: true
maxOpenFiles: 1000000
maxPods: 110
nodeStatusUpdateFrequency: 10s
oomScoreAdj: -999
podPidsLimit: -1
registryBurst: 10
registryPullQPS: 5
resolvConf: /etc/resolv.conf
rotateCertificates: true
runtimeRequestTimeout: 2m0s
serializeImagePulls: true
staticPodPath: /etc/kubernetes/manifests
streamingConnectionIdleTimeout: 4h0m0s
syncFrequency: 1m0s
volumeStatsAggPeriod: 1m0s

2. 组件概览

顾名思义，SecretManager就是用于管理Secret资源对象的，它缓存了所有的Secret，并且负责向给定的Pod中注入/撤销Secret

3. 源码剖析

3.1. SecretManager

SecretManager

我们先来看看SecretManager的定义

只有GetSecret这个接口是有用的，顾名思义，就是通过资源的name以及namespace获取Secret

type Manager interface {
	GetSecret(namespace, name string) (*v1.Secret, error)

	RegisterPod(pod *v1.Pod)

	UnregisterPod(pod *v1.Pod)
}

3.2. simpleSecretManager

simpleSecretManager

simpleSecretManager为Manager的简单实现，GetSecret接口的实现也非常的简单，就是通过apiserver获取secret。而RegistePod以及UnRegisterPod为空。

type simpleSecretManager struct {
	kubeClient clientset.Interface
}

// NewSimpleSecretManager creates a new SecretManager instance.
func NewSimpleSecretManager(kubeClient clientset.Interface) Manager {
	return &simpleSecretManager{kubeClient: kubeClient}
}

func (s *simpleSecretManager) GetSecret(namespace, name string) (*v1.Secret, error) {
	return s.kubeClient.CoreV1().Secrets(namespace).Get(context.TODO(), name, metav1.GetOptions{})
}

func (s *simpleSecretManager) RegisterPod(pod *v1.Pod) {
}

func (s *simpleSecretManager) UnregisterPod(pod *v1.Pod) {
}

3.3. secretManager

secretManager

secretManager借助于Util.Manager实现的，而Util.Manager有两种实现，一个为CachedBasedManager，另外一个则是WatchedBasedManager

type secretManager struct {
	manager manager.Manager
}

func (s *secretManager) GetSecret(namespace, name string) (*v1.Secret, error) {
	object, err := s.manager.GetObject(namespace, name)
	if err != nil {
		return nil, err
	}
	if secret, ok := object.(*v1.Secret); ok {
		return secret, nil
	}
	return nil, fmt.Errorf("unexpected object type: %v", object)
}

func (s *secretManager) RegisterPod(pod *v1.Pod) {
	s.manager.RegisterPod(pod)
}

func (s *secretManager) UnregisterPod(pod *v1.Pod) {
	s.manager.UnregisterPod(pod)
}

3.4. NewCachingSecretManager

NewCachingSecretManager

func NewCachingSecretManager(kubeClient clientset.Interface, getTTL manager.GetObjectTTLFunc) Manager {
	getSecret := func(namespace, name string, opts metav1.GetOptions) (runtime.Object, error) {
		return kubeClient.CoreV1().Secrets(namespace).Get(context.TODO(), name, opts)
	}
	secretStore := manager.NewObjectStore(getSecret, clock.RealClock{}, getTTL, defaultTTL)
	return &secretManager{
		manager: manager.NewCacheBasedManager(secretStore, getSecretNames),
	}
}

3.5. NewWatchingSecretManager

NewWatchingSecretManager

func NewWatchingSecretManager(kubeClient clientset.Interface, resyncInterval time.Duration) Manager {
	listSecret := func(namespace string, opts metav1.ListOptions) (runtime.Object, error) {
		return kubeClient.CoreV1().Secrets(namespace).List(context.TODO(), opts)
	}
	watchSecret := func(namespace string, opts metav1.ListOptions) (watch.Interface, error) {
		return kubeClient.CoreV1().Secrets(namespace).Watch(context.TODO(), opts)
	}
	newSecret := func() runtime.Object {
		return &v1.Secret{}
	}
	isImmutable := func(object runtime.Object) bool {
		if secret, ok := object.(*v1.Secret); ok {
			return secret.Immutable != nil && *secret.Immutable
		}
		return false
	}
	gr := corev1.Resource("secret")
	return &secretManager{
		manager: manager.NewWatchBasedManager(listSecret, watchSecret, newSecret, isImmutable, gr, resyncInterval, getSecretNames),
	}
}