reconcile host cluster (#2354)

print friendly error when component failed

update dockerfile

pkg/controller/cluster/helper.go

@@ -1 +1,37 @@
 package cluster
+
+import (
+	"k8s.io/client-go/rest"
+	"k8s.io/client-go/tools/clientcmd"
+	"k8s.io/client-go/tools/clientcmd/api"
+)
+
+func buildKubeconfigFromRestConfig(config *rest.Config) ([]byte, error) {
+	apiConfig := api.NewConfig()
+
+	apiConfig.Clusters["kubernetes"] = &api.Cluster{
+		Server:                   config.Host,
+		CertificateAuthorityData: config.CAData,
+		CertificateAuthority:     config.CAFile,
+	}
+
+	apiConfig.AuthInfos["kubernetes-admin"] = &api.AuthInfo{
+		ClientCertificate:     config.CertFile,
+		ClientCertificateData: config.CertData,
+		ClientKey:             config.KeyFile,
+		ClientKeyData:         config.KeyData,
+		TokenFile:             config.BearerTokenFile,
+		Token:                 config.BearerToken,
+		Username:              config.Username,
+		Password:              config.Password,
+	}
+
+	apiConfig.Contexts["kubernetes-admin@kubernetes"] = &api.Context{
+		Cluster:  "kubernetes",
+		AuthInfo: "kubernetes-admin",
+	}
+
+	apiConfig.CurrentContext = "kubernetes-admin@kubernetes"
+
+	return clientcmd.Write(*apiConfig)
+}