e84365f967
Ideally, this should actually do a lookup across images that have no parent, but I wasn't 100% sure how to accomplish that so I opted for the smaller change of having `FROM scratch` builds not be cached for now.
Signed-off-by: Tianon Gravi <admwiggin@gmail.com>
(cherry picked from commit 1741771b67)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
93 lines
2.3 KiB
Go
93 lines
2.3 KiB
Go
package containerd
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import (
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"context"
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"reflect"
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"strings"
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"github.com/docker/docker/api/types/container"
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imagetype "github.com/docker/docker/api/types/image"
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"github.com/docker/docker/builder"
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"github.com/docker/docker/image"
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)
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// MakeImageCache creates a stateful image cache.
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func (i *ImageService) MakeImageCache(ctx context.Context, cacheFrom []string) (builder.ImageCache, error) {
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images := []*image.Image{}
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for _, c := range cacheFrom {
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im, err := i.GetImage(ctx, c, imagetype.GetImageOpts{})
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if err != nil {
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return nil, err
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}
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images = append(images, im)
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}
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return &imageCache{images: images, c: i}, nil
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}
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type imageCache struct {
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images []*image.Image
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c *ImageService
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}
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func (ic *imageCache) GetCache(parentID string, cfg *container.Config) (imageID string, err error) {
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ctx := context.TODO()
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if parentID == "" {
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// TODO handle "parentless" image cache lookups ("FROM scratch")
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return "", nil
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}
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parent, err := ic.c.GetImage(ctx, parentID, imagetype.GetImageOpts{})
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if err != nil {
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return "", err
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}
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for _, localCachedImage := range ic.images {
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if isMatch(localCachedImage, parent, cfg) {
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return localCachedImage.ID().String(), nil
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}
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}
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children, err := ic.c.Children(ctx, parent.ID())
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if err != nil {
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return "", err
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}
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for _, children := range children {
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childImage, err := ic.c.GetImage(ctx, children.String(), imagetype.GetImageOpts{})
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if err != nil {
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return "", err
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}
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if isMatch(childImage, parent, cfg) {
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return children.String(), nil
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}
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}
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return "", nil
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}
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// isMatch checks whether a given target can be used as cache for the given
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// parent image/config combination.
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// A target can only be an immediate child of the given parent image. For
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// a parent image with `n` history entries, a valid target must have `n+1`
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// entries and the extra entry must match the provided config
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func isMatch(target, parent *image.Image, cfg *container.Config) bool {
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if target == nil || parent == nil || cfg == nil {
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return false
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}
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if len(target.History) != len(parent.History)+1 ||
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len(target.RootFS.DiffIDs) != len(parent.RootFS.DiffIDs)+1 {
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return false
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}
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for i := range parent.History {
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if !reflect.DeepEqual(parent.History[i], target.History[i]) {
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return false
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}
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}
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childCreatedBy := target.History[len(target.History)-1].CreatedBy
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return childCreatedBy == strings.Join(cfg.Cmd, " ")
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}
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