use_context.go

Documentation: k8s.io/kubectl/pkg/cmd/config

     1  /*
     2  Copyright 2014 The Kubernetes Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package config
    18  
    19  import (
    20  	"errors"
    21  	"fmt"
    22  	"io"
    23  
    24  	"github.com/spf13/cobra"
    25  
    26  	"k8s.io/client-go/tools/clientcmd"
    27  	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
    28  	cmdutil "k8s.io/kubectl/pkg/cmd/util"
    29  	"k8s.io/kubectl/pkg/util/completion"
    30  	"k8s.io/kubectl/pkg/util/i18n"
    31  	"k8s.io/kubectl/pkg/util/templates"
    32  )
    33  
    34  var (
    35  	useContextExample = templates.Examples(`
    36  		# Use the context for the minikube cluster
    37  		kubectl config use-context minikube`)
    38  )
    39  
    40  type useContextOptions struct {
    41  	configAccess clientcmd.ConfigAccess
    42  	contextName  string
    43  }
    44  
    45  // NewCmdConfigUseContext returns a Command instance for 'config use-context' sub command
    46  func NewCmdConfigUseContext(out io.Writer, configAccess clientcmd.ConfigAccess) *cobra.Command {
    47  	options := &useContextOptions{configAccess: configAccess}
    48  
    49  	cmd := &cobra.Command{
    50  		Use:                   "use-context CONTEXT_NAME",
    51  		DisableFlagsInUseLine: true,
    52  		Short:                 i18n.T("Set the current-context in a kubeconfig file"),
    53  		Aliases:               []string{"use"},
    54  		Long:                  `Set the current-context in a kubeconfig file.`,
    55  		Example:               useContextExample,
    56  		ValidArgsFunction:     completion.ContextCompletionFunc,
    57  		Run: func(cmd *cobra.Command, args []string) {
    58  			cmdutil.CheckErr(options.complete(cmd))
    59  			cmdutil.CheckErr(options.run())
    60  			fmt.Fprintf(out, "Switched to context %q.\n", options.contextName)
    61  		},
    62  	}
    63  
    64  	return cmd
    65  }
    66  
    67  func (o useContextOptions) run() error {
    68  	config, err := o.configAccess.GetStartingConfig()
    69  	if err != nil {
    70  		return err
    71  	}
    72  
    73  	err = o.validate(config)
    74  	if err != nil {
    75  		return err
    76  	}
    77  
    78  	config.CurrentContext = o.contextName
    79  
    80  	return clientcmd.ModifyConfig(o.configAccess, *config, true)
    81  }
    82  
    83  func (o *useContextOptions) complete(cmd *cobra.Command) error {
    84  	endingArgs := cmd.Flags().Args()
    85  	if len(endingArgs) != 1 {
    86  		return helpErrorf(cmd, "Unexpected args: %v", endingArgs)
    87  	}
    88  
    89  	o.contextName = endingArgs[0]
    90  	return nil
    91  }
    92  
    93  func (o useContextOptions) validate(config *clientcmdapi.Config) error {
    94  	if len(o.contextName) == 0 {
    95  		return errors.New("empty context names are not allowed")
    96  	}
    97  
    98  	for name := range config.Contexts {
    99  		if name == o.contextName {
   100  			return nil
   101  		}
   102  	}
   103  
   104  	return fmt.Errorf("no context exists with the name: %q", o.contextName)
   105  }
   106
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