github.com/coreos/rocket@v1.30.1-0.20200224141603-171c416fac02/rkt/image_export.go (about)

     1  // Copyright 2015 The rkt Authors
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package main
    16  
    17  import (
    18  	"fmt"
    19  	"io"
    20  	"os"
    21  
    22  	"github.com/rkt/rkt/store/imagestore"
    23  
    24  	"github.com/spf13/cobra"
    25  )
    26  
    27  var (
    28  	cmdImageExport = &cobra.Command{
    29  		Use:   "export IMAGE OUTPUT_ACI_FILE",
    30  		Short: "Export a stored image to an ACI file",
    31  		Long: `IMAGE should be a string referencing an image: either an ID or an image name.
    32  
    33  Note that images must be fetched prior to running export and that this command
    34  always returns uncompressed ACIs`,
    35  		Run: runWrapper(runImageExport),
    36  	}
    37  	flagOverwriteACI bool
    38  )
    39  
    40  func init() {
    41  	cmdImage.AddCommand(cmdImageExport)
    42  	cmdImageExport.Flags().BoolVar(&flagOverwriteACI, "overwrite", false, "overwrite output ACI")
    43  }
    44  
    45  func runImageExport(cmd *cobra.Command, args []string) (exit int) {
    46  	if len(args) != 2 {
    47  		cmd.Usage()
    48  		return 254
    49  	}
    50  
    51  	s, err := imagestore.NewStore(storeDir())
    52  	if err != nil {
    53  		stderr.PrintE("cannot open store", err)
    54  		return 254
    55  	}
    56  
    57  	key, err := getStoreKeyFromAppOrHash(s, args[0])
    58  	if err != nil {
    59  		stderr.Error(err)
    60  		return 254
    61  	}
    62  
    63  	aci, err := s.ReadStream(key)
    64  	if err != nil {
    65  		stderr.PrintE("error reading image", err)
    66  		return 254
    67  	}
    68  	defer aci.Close()
    69  
    70  	mode := os.O_CREATE | os.O_WRONLY
    71  	if flagOverwriteACI {
    72  		mode |= os.O_TRUNC
    73  	} else {
    74  		mode |= os.O_EXCL
    75  	}
    76  	f, err := os.OpenFile(args[1], mode, 0644)
    77  	if err != nil {
    78  		if os.IsExist(err) {
    79  			stderr.Print("output ACI file exists (try --overwrite)")
    80  		} else {
    81  			stderr.PrintE(fmt.Sprintf("unable to open output ACI file %s", args[1]), err)
    82  		}
    83  		return 254
    84  	}
    85  	defer func() {
    86  		err := f.Close()
    87  		if err != nil {
    88  			stderr.PrintE("error closing output ACI file", err)
    89  			exit = 1
    90  		}
    91  	}()
    92  
    93  	_, err = io.Copy(f, aci)
    94  	if err != nil {
    95  		stderr.PrintE("error writing to output ACI file", err)
    96  		return 254
    97  	}
    98  
    99  	return 0
   100  }