github.com/jwhonce/docker@v0.6.7-0.20190327063223-da823cf3a5a3/builder/dockerfile/imagecontext.go (about)

     1  package dockerfile // import "github.com/docker/docker/builder/dockerfile"
     2  
     3  import (
     4  	"context"
     5  	"runtime"
     6  
     7  	"github.com/docker/docker/api/types/backend"
     8  	"github.com/docker/docker/builder"
     9  	dockerimage "github.com/docker/docker/image"
    10  	specs "github.com/opencontainers/image-spec/specs-go/v1"
    11  	"github.com/pkg/errors"
    12  	"github.com/sirupsen/logrus"
    13  )
    14  
    15  type getAndMountFunc func(string, bool, *specs.Platform) (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, platform *specs.Platform) (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  		return options.Backend.GetImageAndReleasableLayer(ctx, idOrRef, backend.GetImageAndLayerOptions{
    36  			PullOption: pullOption,
    37  			AuthConfig: options.Options.AuthConfigs,
    38  			Output:     options.ProgressWriter.Output,
    39  			Platform:   platform,
    40  		})
    41  	}
    42  
    43  	return &imageSources{
    44  		byImageID: make(map[string]*imageMount),
    45  		getImage:  getAndMount,
    46  	}
    47  }
    48  
    49  func (m *imageSources) Get(idOrRef string, localOnly bool, platform *specs.Platform) (*imageMount, error) {
    50  	if im, ok := m.byImageID[idOrRef]; ok {
    51  		return im, nil
    52  	}
    53  
    54  	image, layer, err := m.getImage(idOrRef, localOnly, platform)
    55  	if err != nil {
    56  		return nil, err
    57  	}
    58  	im := newImageMount(image, layer)
    59  	m.Add(im)
    60  	return im, nil
    61  }
    62  
    63  func (m *imageSources) Unmount() (retErr error) {
    64  	for _, im := range m.mounts {
    65  		if err := im.unmount(); err != nil {
    66  			logrus.Error(err)
    67  			retErr = err
    68  		}
    69  	}
    70  	return
    71  }
    72  
    73  func (m *imageSources) Add(im *imageMount) {
    74  	switch im.image {
    75  	case nil:
    76  		// set the OS for scratch images
    77  		os := runtime.GOOS
    78  		// Windows does not support scratch except for LCOW
    79  		if runtime.GOOS == "windows" {
    80  			os = "linux"
    81  		}
    82  		im.image = &dockerimage.Image{V1Image: dockerimage.V1Image{OS: os}}
    83  	default:
    84  		m.byImageID[im.image.ImageID()] = im
    85  	}
    86  	m.mounts = append(m.mounts, im)
    87  }
    88  
    89  // imageMount is a reference to an image that can be used as a builder.Source
    90  type imageMount struct {
    91  	image  builder.Image
    92  	source builder.Source
    93  	layer  builder.ROLayer
    94  }
    95  
    96  func newImageMount(image builder.Image, layer builder.ROLayer) *imageMount {
    97  	im := &imageMount{image: image, layer: layer}
    98  	return im
    99  }
   100  
   101  func (im *imageMount) unmount() error {
   102  	if im.layer == nil {
   103  		return nil
   104  	}
   105  	if err := im.layer.Release(); err != nil {
   106  		return errors.Wrapf(err, "failed to unmount previous build image %s", im.image.ImageID())
   107  	}
   108  	im.layer = nil
   109  	return nil
   110  }
   111  
   112  func (im *imageMount) Image() builder.Image {
   113  	return im.image
   114  }
   115  
   116  func (im *imageMount) NewRWLayer() (builder.RWLayer, error) {
   117  	return im.layer.NewRWLayer()
   118  }
   119  
   120  func (im *imageMount) ImageID() string {
   121  	return im.image.ImageID()
   122  }