github.com/rita33cool1/iot-system-gateway@v0.0.0-20200911033302-e65bde238cc5/docker-engine/builder/dockerfile/imagecontext.go (about)

     1  package dockerfile // import "github.com/docker/docker/builder/dockerfile"
     2  
     3  import (
     4  	"runtime"
     5  
     6  	"github.com/docker/docker/api/types/backend"
     7  	"github.com/docker/docker/builder"
     8  	dockerimage "github.com/docker/docker/image"
     9  	"github.com/docker/docker/pkg/system"
    10  	"github.com/pkg/errors"
    11  	"github.com/sirupsen/logrus"
    12  	"golang.org/x/net/context"
    13  )
    14  
    15  type getAndMountFunc func(string, bool) (builder.Image, builder.ROLayer, error)
    16  
    17  // imageSources mounts images and provides a cache for mounted images. It tracks
    18  // all images so they can be unmounted at the end of the build.
    19  type imageSources struct {
    20  	byImageID map[string]*imageMount
    21  	mounts    []*imageMount
    22  	getImage  getAndMountFunc
    23  }
    24  
    25  func newImageSources(ctx context.Context, options builderOptions) *imageSources {
    26  	getAndMount := func(idOrRef string, localOnly bool) (builder.Image, builder.ROLayer, error) {
    27  		pullOption := backend.PullOptionNoPull
    28  		if !localOnly {
    29  			if options.Options.PullParent {
    30  				pullOption = backend.PullOptionForcePull
    31  			} else {
    32  				pullOption = backend.PullOptionPreferLocal
    33  			}
    34  		}
    35  		optionsPlatform := system.ParsePlatform(options.Options.Platform)
    36  		return options.Backend.GetImageAndReleasableLayer(ctx, idOrRef, backend.GetImageAndLayerOptions{
    37  			PullOption: pullOption,
    38  			AuthConfig: options.Options.AuthConfigs,
    39  			Output:     options.ProgressWriter.Output,
    40  			OS:         optionsPlatform.OS,
    41  		})
    42  	}
    43  
    44  	return &imageSources{
    45  		byImageID: make(map[string]*imageMount),
    46  		getImage:  getAndMount,
    47  	}
    48  }
    49  
    50  func (m *imageSources) Get(idOrRef string, localOnly bool) (*imageMount, error) {
    51  	if im, ok := m.byImageID[idOrRef]; ok {
    52  		return im, nil
    53  	}
    54  
    55  	image, layer, err := m.getImage(idOrRef, localOnly)
    56  	if err != nil {
    57  		return nil, err
    58  	}
    59  	im := newImageMount(image, layer)
    60  	m.Add(im)
    61  	return im, nil
    62  }
    63  
    64  func (m *imageSources) Unmount() (retErr error) {
    65  	for _, im := range m.mounts {
    66  		if err := im.unmount(); err != nil {
    67  			logrus.Error(err)
    68  			retErr = err
    69  		}
    70  	}
    71  	return
    72  }
    73  
    74  func (m *imageSources) Add(im *imageMount) {
    75  	switch im.image {
    76  	case nil:
    77  		// set the OS for scratch images
    78  		os := runtime.GOOS
    79  		// Windows does not support scratch except for LCOW
    80  		if runtime.GOOS == "windows" {
    81  			os = "linux"
    82  		}
    83  		im.image = &dockerimage.Image{V1Image: dockerimage.V1Image{OS: os}}
    84  	default:
    85  		m.byImageID[im.image.ImageID()] = im
    86  	}
    87  	m.mounts = append(m.mounts, im)
    88  }
    89  
    90  // imageMount is a reference to an image that can be used as a builder.Source
    91  type imageMount struct {
    92  	image  builder.Image
    93  	source builder.Source
    94  	layer  builder.ROLayer
    95  }
    96  
    97  func newImageMount(image builder.Image, layer builder.ROLayer) *imageMount {
    98  	im := &imageMount{image: image, layer: layer}
    99  	return im
   100  }
   101  
   102  func (im *imageMount) unmount() error {
   103  	if im.layer == nil {
   104  		return nil
   105  	}
   106  	if err := im.layer.Release(); err != nil {
   107  		return errors.Wrapf(err, "failed to unmount previous build image %s", im.image.ImageID())
   108  	}
   109  	im.layer = nil
   110  	return nil
   111  }
   112  
   113  func (im *imageMount) Image() builder.Image {
   114  	return im.image
   115  }
   116  
   117  func (im *imageMount) NewRWLayer() (builder.RWLayer, error) {
   118  	return im.layer.NewRWLayer()
   119  }
   120  
   121  func (im *imageMount) ImageID() string {
   122  	return im.image.ImageID()
   123  }