Merge pull request #15828 from justinsb/dont_rely_on_kubectl

Don't rely on kubectl being installed

cmd/kops/update_cluster.go

@@ -37,7 +37,6 @@ import (
 	"k8s.io/kops/upup/pkg/fi"
 	"k8s.io/kops/upup/pkg/fi/cloudup"
 	"k8s.io/kops/upup/pkg/fi/utils"
-	"k8s.io/kops/upup/pkg/kutil"
 	"k8s.io/kubectl/pkg/util/i18n"
 	"k8s.io/kubectl/pkg/util/templates"
 )
@@ -313,12 +312,12 @@ func RunUpdateCluster(ctx context.Context, f *util.Factory, out io.Writer, c *Up
 	firstRun := false
 
 	if !isDryrun && c.CreateKubecfg {
-		hasKubecfg, err := hasKubecfg(cluster.ObjectMeta.Name)
+		hasKubeconfig, err := clusterIsInKubeConfig(cluster.ObjectMeta.Name)
 		if err != nil {
-			klog.Warningf("error reading kubecfg: %v", err)
-			hasKubecfg = true
+			klog.Warningf("error reading kubeconfig: %v", err)
+			hasKubeconfig = true
 		}
-		firstRun = !hasKubecfg
+		firstRun = !hasKubeconfig
 
 		klog.Infof("Exporting kubeconfig for cluster")
 
@@ -439,19 +438,21 @@ func findBastionPublicName(c *kops.Cluster) string {
 	return bastion.PublicName
 }
 
-func hasKubecfg(contextName string) (bool, error) {
-	kubectl := &kutil.Kubectl{}
-
-	config, err := kubectl.GetConfig(false)
+// clusterIsInKubeConfig checks if we have a context with the specified name (cluster name) in ~/.kube/config.
+// It is used as a check to see if this is (likely) a new cluster.
+func clusterIsInKubeConfig(contextName string) (bool, error) {
+	configAccess := clientcmd.NewDefaultPathOptions()
+	config, err := configAccess.GetStartingConfig()
 	if err != nil {
-		return false, fmt.Errorf("error getting config from kubectl: %v", err)
+		return false, fmt.Errorf("error reading kubeconfig: %w", err)
 	}
 
-	for _, context := range config.Contexts {
-		if context.Name == contextName {
+	for k := range config.Contexts {
+		if k == contextName {
 			return true, nil
 		}
 	}
+
 	return false, nil
 }
 

upup/pkg/kutil/kubectl.go

@@ -1,90 +0,0 @@
-/*
-Copyright 2019 The Kubernetes Authors.
-
-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 kutil
-
-import (
-	"bytes"
-	"encoding/json"
-	"fmt"
-	"os"
-	"os/exec"
-	"strings"
-
-	"k8s.io/klog/v2"
-	"k8s.io/kops/pkg/kubeconfig"
-)
-
-type Kubectl struct {
-	KubectlPath string
-}
-
-func (k *Kubectl) GetConfig(minify bool) (*kubeconfig.KubectlConfig, error) {
-	output := "json"
-	// TODO: --context doesn't seem to work
-	args := []string{"config", "view"}
-
-	if minify {
-		args = append(args, "--minify")
-	}
-
-	if output != "" {
-		args = append(args, "--output", output)
-	}
-
-	configString, _, err := k.execKubectl(args...)
-	if err != nil {
-		return nil, err
-	}
-	configString = strings.TrimSpace(configString)
-
-	klog.V(8).Infof("config = %q", configString)
-
-	config := &kubeconfig.KubectlConfig{}
-	err = json.Unmarshal([]byte(configString), config)
-	if err != nil {
-		return nil, fmt.Errorf("cannot parse current config from kubectl: %v", err)
-	}
-
-	return config, nil
-}
-
-func (k *Kubectl) execKubectl(args ...string) (string, string, error) {
-	kubectlPath := k.KubectlPath
-	if kubectlPath == "" {
-		kubectlPath = "kubectl" // Assume in PATH
-	}
-	cmd := exec.Command(kubectlPath, args...)
-	env := os.Environ()
-	cmd.Env = env
-	var stdout bytes.Buffer
-	cmd.Stdout = &stdout
-
-	var stderr bytes.Buffer
-	cmd.Stderr = &stderr
-
-	human := strings.Join(cmd.Args, " ")
-	klog.V(2).Infof("Running command: %s", human)
-	err := cmd.Run()
-	if err != nil {
-		klog.Infof("error running %s", human)
-		klog.Info(stdout.String())
-		klog.Info(stderr.String())
-		return stdout.String(), stderr.String(), fmt.Errorf("error running kubectl: %v", err)
-	}
-
-	return stdout.String(), stderr.String(), err
-}