Refactor imageContexts into two different structs.

buildStages now tracks the imageID and runConfig for a build stage

imageMounter tracks image mounts so they can released when the build ends.

Signed-off-by: Daniel Nephin <[email protected]>

api/types/backend/build.go

@@ -23,7 +23,7 @@ type BuildConfig struct {
 	Options        *types.ImageBuildOptions
 }
 
-// GetImageAndLayerOptions are the options supported by GetImageAndLayer
+// GetImageAndLayerOptions are the options supported by GetImageAndReleasableLayer
 type GetImageAndLayerOptions struct {
 	ForcePull  bool
 	AuthConfig map[string]types.AuthConfig

builder/builder.go

@@ -34,7 +34,7 @@ type Source interface {
 
 // Backend abstracts calls to a Docker Daemon.
 type Backend interface {
-	GetImageAndLayer(ctx context.Context, refOrID string, opts backend.GetImageAndLayerOptions) (Image, ReleaseableLayer, error)
+	ImageBackend
 
 	// ContainerAttachRaw attaches to container.
 	ContainerAttachRaw(cID string, stdin io.ReadCloser, stdout, stderr io.Writer, stream bool, attached chan struct{}) error
@@ -60,6 +60,11 @@ type Backend interface {
 	CopyOnBuild(containerID string, destPath string, srcRoot string, srcPath string, decompress bool) error
 }
 
+// ImageBackend are the interface methods required from an image component
+type ImageBackend interface {
+	GetImageAndReleasableLayer(ctx context.Context, refOrID string, opts backend.GetImageAndLayerOptions) (Image, ReleaseableLayer, error)
+}
+
 // Result is the output produced by a Builder
 type Result struct {
 	ImageID   string
@@ -89,5 +94,5 @@ type Image interface {
 // ReleaseableLayer is an image layer that can be mounted and released
 type ReleaseableLayer interface {
 	Release() error
-	Mount(string) (string, error)
+	Mount() (string, error)
 }

builder/dockerfile/builder.go

@@ -102,11 +102,12 @@ type Builder struct {
 	clientCtx context.Context
 
 	tmpContainers map[string]struct{}
-	imageContexts *imageContexts // helper for storing contexts from builds
+	buildStages   *buildStages
 	disableCommit bool
 	cacheBusted   bool
 	buildArgs     *buildArgs
 	imageCache    builder.ImageCache
+	imageSources  *imageSources
 }
 
 // newBuilder creates a new Dockerfile builder from an optional dockerfile and a Options.
@@ -125,7 +126,8 @@ func newBuilder(clientCtx context.Context, options builderOptions) *Builder {
 		docker:        options.Backend,
 		tmpContainers: map[string]struct{}{},
 		buildArgs:     newBuildArgs(config.BuildArgs),
-		imageContexts: &imageContexts{},
+		buildStages:   newBuildStages(),
+		imageSources:  newImageSources(clientCtx, options),
 	}
 	return b
 }
@@ -140,7 +142,7 @@ func (b *Builder) resetImageCache() {
 // Build runs the Dockerfile builder by parsing the Dockerfile and executing
 // the instructions from the file.
 func (b *Builder) build(source builder.Source, dockerfile *parser.Result) (*builder.Result, error) {
-	defer b.imageContexts.unmount()
+	defer b.imageSources.Unmount()
 
 	// TODO: Remove source field from Builder
 	b.source = source

builder/dockerfile/dispatchers.go

@@ -20,9 +20,9 @@ import (
 	"github.com/Sirupsen/logrus"
 	"github.com/docker/docker/api"
 	"github.com/docker/docker/api/types"
-	"github.com/docker/docker/api/types/backend"
 	"github.com/docker/docker/api/types/container"
 	"github.com/docker/docker/api/types/strslice"
+	"github.com/docker/docker/builder"
 	"github.com/docker/docker/builder/dockerfile/parser"
 	"github.com/docker/docker/pkg/signal"
 	"github.com/docker/go-connections/nat"
@@ -174,14 +174,19 @@ func dispatchCopy(req dispatchRequest) error {
 
 func (b *Builder) getImageMount(fromFlag *Flag) (*imageMount, error) {
 	if !fromFlag.IsUsed() {
-		// TODO: this could return the mount in the default case as well
+		// TODO: this could return the source in the default case as well?
 		return nil, nil
 	}
-	im, err := b.imageContexts.getMount(fromFlag.Value)
-	if err != nil || im != nil {
-		return im, err
+
+	imageRefOrID := fromFlag.Value
+	stage, err := b.buildStages.get(fromFlag.Value)
+	if err != nil {
+		return nil, err
+	}
+	if stage != nil {
+		imageRefOrID = stage.ImageID()
 	}
-	return b.getImage(fromFlag.Value)
+	return b.imageSources.Get(imageRefOrID)
 }
 
 // FROM imagename[:tag | @digest] [AS build-stage-name]
@@ -201,7 +206,7 @@ func from(req dispatchRequest) error {
 	if err != nil {
 		return err
 	}
-	if err := req.builder.imageContexts.add(stageName, image); err != nil {
+	if err := req.builder.buildStages.add(stageName, image); err != nil {
 		return err
 	}
 	req.state.beginStage(stageName, image)
@@ -229,7 +234,12 @@ func parseBuildStageName(args []string) (string, error) {
 	return stageName, nil
 }
 
-func (b *Builder) getFromImage(shlex *ShellLex, name string) (*imageMount, error) {
+// scratchImage is used as a token for the empty base image. It uses buildStage
+// as a convenient implementation of builder.Image, but is not actually a
+// buildStage.
+var scratchImage builder.Image = &buildStage{}
+
+func (b *Builder) getFromImage(shlex *ShellLex, name string) (builder.Image, error) {
 	substitutionArgs := []string{}
 	for key, value := range b.buildArgs.GetAllMeta() {
 		substitutionArgs = append(substitutionArgs, key+"="+value)
@@ -240,7 +250,7 @@ func (b *Builder) getFromImage(shlex *ShellLex, name string) (*imageMount, error
 		return nil, err
 	}
 
-	if im, ok := b.imageContexts.byName[name]; ok {
+	if im, ok := b.buildStages.getByName(name); ok {
 		return im, nil
 	}
 
@@ -249,21 +259,13 @@ func (b *Builder) getFromImage(shlex *ShellLex, name string) (*imageMount, error
 		if runtime.GOOS == "windows" {
 			return nil, errors.New("Windows does not support FROM scratch")
 		}
-		return newImageMount(nil, nil), nil
+		return scratchImage, nil
 	}
-	return b.getImage(name)
-}
-
-func (b *Builder) getImage(name string) (*imageMount, error) {
-	image, layer, err := b.docker.GetImageAndLayer(b.clientCtx, name, backend.GetImageAndLayerOptions{
-		ForcePull:  b.options.PullParent,
-		AuthConfig: b.options.AuthConfigs,
-		Output:     b.Output,
-	})
+	imageMount, err := b.imageSources.Get(name)
 	if err != nil {
 		return nil, err
 	}
-	return newImageMount(image, layer), nil
+	return imageMount.Image(), nil
 }
 
 func processOnBuild(req dispatchRequest) error {

builder/dockerfile/dispatchers_test.go

@@ -49,15 +49,20 @@ func defaultDispatchReq(builder *Builder, args ...string) dispatchRequest {
 
 func newBuilderWithMockBackend() *Builder {
 	mockBackend := &MockBackend{}
+	ctx := context.Background()
 	b := &Builder{
 		options:       &types.ImageBuildOptions{},
 		docker:        mockBackend,
 		buildArgs:     newBuildArgs(make(map[string]*string)),
 		tmpContainers: make(map[string]struct{}),
 		Stdout:        new(bytes.Buffer),
-		clientCtx:     context.Background(),
+		clientCtx:     ctx,
 		disableCommit: true,
-		imageContexts: &imageContexts{},
+		imageSources: newImageSources(ctx, builderOptions{
+			Options: &types.ImageBuildOptions{},
+			Backend: mockBackend,
+		}),
+		buildStages: newBuildStages(),
 	}
 	return b
 }