kubeconfig.go

/*
Copyright 2020 Elotl Inc.

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 k8s

import (
	"fmt"
	"strings"

	"github.com/elotl/kip/pkg/util"
	"github.com/elotl/kip/pkg/util/kubeconfig"
	"github.com/elotl/node-cli/manager"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/tools/clientcmd"
	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
)

func CreateKubeConfigFromSecret(rm *manager.ResourceManager, kubeConfigPath, saSecret string) (*clientcmdapi.Config, error) {
	serverURL := GetServerURL(kubeConfigPath)
	if serverURL == "" {
		return nil, fmt.Errorf("can't determine API server URL, set --kubeconfig or MASTER_URI")
	}
	kc, err := createKubeConfigFromSecret(rm, serverURL, saSecret)
	if err != nil {
		return nil, util.WrapError(err, "creating kubeconfig from service account secret")
	}
	if err := validateKubeconfig(kc); err != nil {
		return nil, util.WrapError(err, "validating kubeconfig")
	}
	return kc, err
}

func createKubeConfigFromSecret(rm *manager.ResourceManager, serverURL, saSecret string) (*clientcmdapi.Config, error) {
	parts := strings.SplitN(saSecret, "/", 2)
	name := parts[len(parts)-1]
	namespace := "default"
	if len(parts) > 1 {
		namespace = parts[0]
	}
	secret, err := rm.GetSecret(name, namespace)
	if err != nil {
		return nil, util.WrapError(err, "retrieving %q/%q", namespace, name)
	}
	token, ok := secret.Data["token"]
	if !ok {
		return nil, fmt.Errorf("missing token in service account secret")
	}
	cacrt, ok := secret.Data["ca.crt"]
	if !ok {
		return nil, fmt.Errorf("missing CA cert in service account secret")
	}
	cfg := kubeconfig.CreateFromToken(serverURL, "", name, cacrt, token)
	return cfg, nil
}

func validateKubeconfig(config *clientcmdapi.Config) error {
	cc, err := clientcmd.NewDefaultClientConfig(*config, &clientcmd.ConfigOverrides{}).ClientConfig()
	if err != nil {
		return util.WrapError(err, "getting client config")
	}
	clientset, err := kubernetes.NewForConfig(cc)
	if err != nil {
		return util.WrapError(err, "getting clientset")
	}
	_, err = clientset.ServerVersion()
	if err != nil {
		return util.WrapError(err, "getting server version")
	}
	return nil
}