append.go

Documentation: github.com/google/go-containerregistry/pkg/crane

     1  // Copyright 2018 Google LLC All Rights Reserved.
     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 crane
    16  
    17  import (
    18  	"fmt"
    19  	"os"
    20  
    21  	"github.com/google/go-containerregistry/internal/windows"
    22  	v1 "github.com/google/go-containerregistry/pkg/v1"
    23  	"github.com/google/go-containerregistry/pkg/v1/mutate"
    24  	"github.com/google/go-containerregistry/pkg/v1/stream"
    25  	"github.com/google/go-containerregistry/pkg/v1/tarball"
    26  	"github.com/google/go-containerregistry/pkg/v1/types"
    27  )
    28  
    29  func isWindows(img v1.Image) (bool, error) {
    30  	cfg, err := img.ConfigFile()
    31  	if err != nil {
    32  		return false, err
    33  	}
    34  	return cfg != nil && cfg.OS == "windows", nil
    35  }
    36  
    37  // Append reads a layer from path and appends it the the v1.Image base.
    38  //
    39  // If the base image is a Windows base image (i.e., its config.OS is
    40  // "windows"), the contents of the tarballs will be modified to be suitable for
    41  // a Windows container image.`,
    42  func Append(base v1.Image, paths ...string) (v1.Image, error) {
    43  	if base == nil {
    44  		return nil, fmt.Errorf("invalid argument: base")
    45  	}
    46  
    47  	win, err := isWindows(base)
    48  	if err != nil {
    49  		return nil, fmt.Errorf("getting base image: %w", err)
    50  	}
    51  
    52  	baseMediaType, err := base.MediaType()
    53  
    54  	if err != nil {
    55  		return nil, fmt.Errorf("getting base image media type: %w", err)
    56  	}
    57  
    58  	layerType := types.DockerLayer
    59  
    60  	if baseMediaType == types.OCIManifestSchema1 {
    61  		layerType = types.OCILayer
    62  	}
    63  
    64  	layers := make([]v1.Layer, 0, len(paths))
    65  	for _, path := range paths {
    66  		layer, err := getLayer(path, layerType)
    67  		if err != nil {
    68  			return nil, fmt.Errorf("reading layer %q: %w", path, err)
    69  		}
    70  
    71  		if win {
    72  			layer, err = windows.Windows(layer)
    73  			if err != nil {
    74  				return nil, fmt.Errorf("converting %q for Windows: %w", path, err)
    75  			}
    76  		}
    77  
    78  		layers = append(layers, layer)
    79  	}
    80  
    81  	return mutate.AppendLayers(base, layers...)
    82  }
    83  
    84  func getLayer(path string, layerType types.MediaType) (v1.Layer, error) {
    85  	f, err := streamFile(path)
    86  	if err != nil {
    87  		return nil, err
    88  	}
    89  	if f != nil {
    90  		return stream.NewLayer(f, stream.WithMediaType(layerType)), nil
    91  	}
    92  
    93  	return tarball.LayerFromFile(path, tarball.WithMediaType(layerType))
    94  }
    95  
    96  // If we're dealing with a named pipe, trying to open it multiple times will
    97  // fail, so we need to do a streaming upload.
    98  //
    99  // returns nil, nil for non-streaming files
   100  func streamFile(path string) (*os.File, error) {
   101  	if path == "-" {
   102  		return os.Stdin, nil
   103  	}
   104  	fi, err := os.Stat(path)
   105  	if err != nil {
   106  		return nil, err
   107  	}
   108  
   109  	if !fi.Mode().IsRegular() {
   110  		return os.Open(path)
   111  	}
   112  
   113  	return nil, nil
   114  }
   115
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