Add GenerateKubeConfiguration helper (#541)

Signed-off-by: Tamal Saha <tamal@appscode.com>

tools/clientcmd/rest_config.go

@@ -0,0 +1,74 @@
+/*
+Copyright AppsCode Inc. and Contributors
+
+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 clientcmd
+
+import (
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/client-go/rest"
+	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
+	clientcmdlatest "k8s.io/client-go/tools/clientcmd/api/latest"
+)
+
+// https://github.com/kubernetes/client-go/issues/711#issuecomment-730112049
+func GenerateKubeConfiguration(cfg *rest.Config, namespace string) ([]byte, error) {
+	if err := rest.LoadTLSFiles(cfg); err != nil {
+		return nil, err
+	}
+
+	clusters := make(map[string]*clientcmdapi.Cluster)
+	clusters["default-cluster"] = &clientcmdapi.Cluster{
+		Server:                   cfg.Host,
+		CertificateAuthorityData: cfg.CAData,
+	}
+
+	contexts := make(map[string]*clientcmdapi.Context)
+	contexts["default-context"] = &clientcmdapi.Context{
+		Cluster:   "default-cluster",
+		Namespace: namespace,
+		AuthInfo:  "default-user",
+	}
+
+	authinfos := make(map[string]*clientcmdapi.AuthInfo)
+	authinfos["default-user"] = &clientcmdapi.AuthInfo{
+		LocationOfOrigin:      "",
+		ClientCertificate:     "",
+		ClientCertificateData: cfg.CertData,
+		ClientKey:             "",
+		ClientKeyData:         cfg.KeyData,
+		Token:                 cfg.BearerToken,
+		TokenFile:             "",
+		Impersonate:           cfg.Impersonate.UserName,
+		ImpersonateUID:        cfg.Impersonate.UID,
+		ImpersonateGroups:     cfg.Impersonate.Groups,
+		ImpersonateUserExtra:  cfg.Impersonate.Extra,
+		Username:              cfg.Username,
+		Password:              cfg.Password,
+		AuthProvider:          cfg.AuthProvider,
+		Exec:                  cfg.ExecProvider,
+		Extensions:            nil,
+	}
+
+	clientConfig := clientcmdapi.Config{
+		Kind:           "Config",
+		APIVersion:     "v1",
+		Clusters:       clusters,
+		Contexts:       contexts,
+		CurrentContext: "default-context",
+		AuthInfos:      authinfos,
+	}
+	return runtime.Encode(clientcmdlatest.Codec, &clientConfig)
+}