k8s源码学习-使用list方法获取各种资源（基于client-go+kubeconfig）

k8s源码学习-使用list方法获取各种资源（基于client-go+kubeconfig）

初始化项目

git:(master) ✗ lsREADME.md main.gogit:(master) ✗ go mod init appgo: creating new go.mod: module appgo: to add module requirements and sums: go mod tidygit:(master) ✗ lsREADME.md go.mod main.go

解决项目依赖

✗ go mod tidygo: finding module for package k8s.io/client-go/tools/clientcmdgo: finding module for package k8s.io/client-go/kubernetesgo: finding module for package k8s.io/apimachinery/pkg/apis/meta/v1go: finding module for package k8s.io/client-go/restgo: found k8s.io/apimachinery/pkg/apis/meta/v1 in k8s.io/apimachinery v0.23.5go: found k8s.io/client-go/kubernetes in k8s.io/client-go v0.23.5go: found k8s.io/client-go/rest in k8s.io/client-go v0.23.5go: found k8s.io/client-go/tools/clientcmd in k8s.io/client-go v0.23.5git:(master) ✗ lsREADME.md go.mod go.sum main.go

运行代码，获取指定命名空间下的pod、deployment、daemonset等信息：

git:(master) ✗ go run main.go 获取default namespace下的podnginx-deployment-9456bbbf9-78z87nginx-deployment-9456bbbf9-7tgnmnginx-deployment-9456bbbf9-n4mchtest-incluster-client-go获取default namespace下的deployment的名字 nginx-deployment获取kube-system namespace下的daemonset的名字 kube-proxy获取get node的方法 minikube获取kube-system svckube-dns

代码解读：​​项目代码​​

package mainimport ( "context" "flag" "fmt" metav1 "k8s.io/apimachinery/pkg/apis/meta/v1" "k8s.io/client-go/kubernetes" "k8s.io/client-go/rest" "k8s.io/client-go/tools/clientcmd")func main() { // 一个简单的client-go使用外部kubeconfig文件交互k8s API，这里指定minikube的config配置文件路径 kubeconfig := flag.String("kubeconfig", "/Users/XXXX/.kube/config", "location to your kubeconfig file") config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig) if err != nil { // handle error fmt.Printf("erorr %s building config from flags\n", err.Error()) config, err = rest.InClusterConfig() if err != nil { fmt.Printf("error %s, getting inclusterconfig", err.Error()) } } //实例化clientset对象 clientset, err := kubernetes.NewForConfig(config) if err != nil { // handle error fmt.Printf("error %s, creating clientset\n", err.Error()) } ctx := context.Background() fmt.Println("获取default namespace下的pod") //1、获取default下pod的名字 pods, err := clientset.CoreV1().Pods("default").List(ctx, metav1.ListOptions{}) if err != nil { // handle error fmt.Printf("error %s, while listing all the pods from default namespace\n", err.Error()) } //在k8s源码当中 //type PodList struct 定义了podlist ,Items []Pod定义了包含切片Pod的项目 //metav1.TypeMeta `json:",inline"` // Standard list metadata. // More info: // +optional //metav1.ListMeta `json:"metadata,omitempty" protobuf:"bytes,1,opt,name=metadata"` // List of pods. // More info: //Items []Pod `json:"items" protobuf:"bytes,2,rep,name=items"` //所以我们就可以之间使用for循环取出此切片的长度了 for _, pod := range pods.Items { fmt.Printf("%s\n", pod.Name) } fmt.Println("获取default namespace下的deployment的名字 ") //2、获取default下deployment的资源名字 deployments, err := clientset.AppsV1().Deployments("default").List(ctx, metav1.ListOptions{}) if err != nil { fmt.Printf("listing deployments %s\n", err.Error()) } for _, d := range deployments.Items { fmt.Printf("%s\n", d.Name) } fmt.Println("获取kube-system namespace下的daemonset的名字 ") //3、获取kube-system下daemonset的资源名字 daemonsets, err := clientset.AppsV1().DaemonSets("kube-system").List(ctx, metav1.ListOptions{}) if err != nil { fmt.Printf("listing daemonsets %s\n", err.Error()) } for _, ds := range daemonsets.Items { fmt.Printf("%s\n", ds.Name) } fmt.Println("获取get node的方法 ") //4、获取get node的的名字 node, err := clientset.CoreV1().Nodes().List(ctx, metav1.ListOptions{}) if err != nil { fmt.Printf("listing Node %s\n", err.Error()) } for _, no := range node.Items { fmt.Printf("%s\n", no.Name) } fmt.Println("获取kube-system svc") //5、获取kube-system下的service svc, err := clientset.CoreV1().Services("kube-system").List(ctx, metav1.ListOptions{}) if err != nil { fmt.Printf("listing service %s\n", err.Error()) } for _, service := range svc.Items { fmt.Printf("%s\n", service.Name) }}

开发技巧：

pkg/registry/core 先找到对应的Group和Kind/resource（GR/GK），例如：pod 核心数据结构： pkg/registry/core/pod/storage/storage.go 参考：​​PodStorage includes storage for pods and all sub resourcestype PodStorage struct { Pod *REST Binding *BindingREST LegacyBinding *LegacyBindingREST Eviction *EvictionREST Status *StatusREST EphemeralContainers *EphemeralContainersREST Log *podrest.LogREST Proxy *podrest.ProxyREST Exec *podrest.ExecREST Attach *podrest.AttachREST PortForward *podrest.PortForwardREST}// REST implements a RESTStorage for podstype REST struct { *genericregistry.Store proxyTransport 如果要开发apps资源下的Deployment，先找到registor.go，找到对应的list接口

// Adds the list of known types to the given scheme.func addKnownTypes(scheme *runtime.Scheme) error { scheme.AddKnownTypes(SchemeGroupVersion, &Deployment{}, &DeploymentList{}, &StatefulSet{}, &StatefulSetList{}, &DaemonSet{}, &DaemonSetList{}, &ReplicaSet{}, &ReplicaSetList{}, &ControllerRevision{}, &ControllerRevisionList{}, ) metav1.AddToGroupVersion(scheme, SchemeGroupVersion) return nil}

再去staging/src/k8s.io/api/apps/v1/types.go找到DeploymentList结构体（&DeploymentList{},Goland可以直接跳转过去）

// DeploymentList is a list of Deployments.type DeploymentList struct { metav1.TypeMeta `json:",inline"` // Standard list metadata. // +optional metav1.ListMeta `json:"metadata,omitempty" protobuf:"bytes,1,opt,name=metadata"` // Items is the list of Deployments. Items []Deployment `json:"items" protobuf:"bytes,2,rep,name=items"`}

如果是pod/node等注册信息，使用的是staging/src/k8s.io/api/core/v1/register.go核心代码，不是staging/src/k8s.io/api/apps/v1了

// Adds the list of known types to the given scheme.func addKnownTypes(scheme *runtime.Scheme) error { scheme.AddKnownTypes(SchemeGroupVersion, &Pod{}, &PodList{}, &PodStatusResult{}, &PodTemplate{}, &PodTemplateList{}, &ReplicationController{}, &ReplicationControllerList{}, &Service{}, &ServiceProxyOptions{}, &ServiceList{}, &Endpoints{}, &EndpointsList{}, &Node{}, &NodeList{}, &NodeProxyOptions{}, &Binding{}, &Event{}, &EventList{}, &List{}, &LimitRange{}, &LimitRangeList{}, &ResourceQuota{}, &ResourceQuotaList{}, &Namespace{}, &NamespaceList{}, &Secret{}, &SecretList{}, &ServiceAccount{}, &ServiceAccountList{}, &PersistentVolume{}, &PersistentVolumeList{}, &PersistentVolumeClaim{}, &PersistentVolumeClaimList{}, &PodAttachOptions{}, &PodLogOptions{}, &PodExecOptions{}, &PodPortForwardOptions{}, &PodProxyOptions{}, &ComponentStatus{}, &ComponentStatusList{}, &SerializedReference{}, &RangeAllocation{}, &ConfigMap{}, &ConfigMapList{}, )

pod/node等结构体也在core/v1下面，Goland可以直接跳转过去：staging/src/k8s.io/api/core/v1/types.go

// NodeList is the whole list of all Nodes which have been registered with master.type NodeList struct { metav1.TypeMeta `json:",inline"` // Standard list metadata. // More info: // +optional metav1.ListMeta `json:"metadata,omitempty" protobuf:"bytes,1,opt,name=metadata"` // List of nodes Items []Node `json:"items" protobuf:"bytes,2,rep,name=items"`}// FinalizerName is the name identifying a finalizer during namespace lifecycle.type FinalizerName string// These are internal finalizer values to Kubernetes, must be qualified name unless defined here or// in metav1.const ( FinalizerKubernetes FinalizerName = "kubernetes")

4.调用方法

deployments, err := clientset.AppsV1().Deployments("default").List(ctx, metav1.ListOptions{})

vendor/k8s.io/client-go/kubernetes/clientset.go  Clientset结构体包含了多个结构体，例如：clientset.AppsV1().Deployments 和  clientset.CoreV1().Nodes等等

// Clientset contains the clients for groups. Each group has exactly one// version included in a Clientset.type Clientset struct { appsV1 *appsv1.AppsV1Client coreV1 *corev1.CoreV1Client .......}

clientset.AppsV1().Deployments输出的是v1.DeploymentList，v1.DeploymentList包含多个[]Deployment的Items

// DeploymentsGetter has a method to return a DeploymentInterface.// A group's client should implement this interface.type DeploymentsGetter interface { Deployments(namespace string) DeploymentInterface}// DeploymentInterface has methods to work with Deployment resources.type DeploymentInterface interface { ..... List(ctx context.Context, opts metav1.ListOptions) (*v1.DeploymentList, error) .....}// DeploymentList is a list of Deployments.type DeploymentList struct { metav1.TypeMeta `json:",inline"` // Standard list metadata. // +optional metav1.ListMeta `json:"metadata,omitempty" protobuf:"bytes,1,opt,name=metadata"` // Items is the list of Deployments. Items []Deployment `json:"items" protobuf:"bytes,2,rep,name=items"`}

5.循环输出打印

for _, d := range deployments.Items { fmt.Printf("%s\n", d.Name)}

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