dotcloud/docker

package images // import "github.com/docker/docker/daemon/images"

import (
    "context"
    "fmt"
    "io"
    "runtime"

    "github.com/containerd/log"
    "github.com/containerd/platforms"
    "github.com/distribution/reference"
    "github.com/docker/docker/api/types/backend"
    "github.com/docker/docker/api/types/registry"
    "github.com/docker/docker/builder"
    "github.com/docker/docker/errdefs"
    "github.com/docker/docker/image"
    "github.com/docker/docker/layer"
    "github.com/docker/docker/pkg/progress"
    "github.com/docker/docker/pkg/streamformatter"
    "github.com/docker/docker/pkg/stringid"
    registrypkg "github.com/docker/docker/registry"
    "github.com/opencontainers/go-digest"
    ocispec "github.com/opencontainers/image-spec/specs-go/v1"
    "github.com/pkg/errors"
)

type roLayer struct {
    released   bool
    layerStore layer.Store
    roLayer    layer.Layer
}

func (l *roLayer) ContentStoreDigest() digest.Digest {
    return ""
}

func (l *roLayer) DiffID() layer.DiffID {
    if l.roLayer == nil {
        return layer.DigestSHA256EmptyTar
    }
    return l.roLayer.DiffID()
}

func (l *roLayer) Release() error {
    if l.released {
        return nil
    }
    if l.roLayer != nil {
        metadata, err := l.layerStore.Release(l.roLayer)
        layer.LogReleaseMetadata(metadata)
        if err != nil {
            return errors.Wrap(err, "failed to release ROLayer")
        }
    }
    l.roLayer = nil
    l.released = true
    return nil
}

func (l *roLayer) NewRWLayer() (builder.RWLayer, error) {
    var chainID layer.ChainID
    if l.roLayer != nil {
        chainID = l.roLayer.ChainID()
    }

    mountID := stringid.GenerateRandomID()
    newLayer, err := l.layerStore.CreateRWLayer(mountID, chainID, nil)
    if err != nil {
        return nil, errors.Wrap(err, "failed to create rwlayer")
    }

    rwLayer := &rwLayer{layerStore: l.layerStore, rwLayer: newLayer}

    fs, err := newLayer.Mount("")
    if err != nil {
        rwLayer.Release()
        return nil, err
    }

    rwLayer.fs = fs

    return rwLayer, nil
}

type rwLayer struct {
    released   bool
    layerStore layer.Store
    rwLayer    layer.RWLayer
    fs         string
}

func (l *rwLayer) Root() string {
    return l.fs
}

func (l *rwLayer) Commit() (builder.ROLayer, error) {
    stream, err := l.rwLayer.TarStream()
    if err != nil {
        return nil, err
    }
    defer stream.Close()

    var chainID layer.ChainID
    if parent := l.rwLayer.Parent(); parent != nil {
        chainID = parent.ChainID()
    }

    newLayer, err := l.layerStore.Register(stream, chainID)
    if err != nil {
        return nil, err
    }
    // TODO: An optimization would be to handle empty layers before returning
    return &roLayer{layerStore: l.layerStore, roLayer: newLayer}, nil
}

func (l *rwLayer) Release() error {
    if l.released {
        return nil
    }

    if l.fs != "" {
        if err := l.rwLayer.Unmount(); err != nil {
            return errors.Wrap(err, "failed to unmount RWLayer")
        }
        l.fs = ""
    }

    metadata, err := l.layerStore.ReleaseRWLayer(l.rwLayer)
    layer.LogReleaseMetadata(metadata)
    if err != nil {
        return errors.Wrap(err, "failed to release RWLayer")
    }
    l.released = true
    return nil
}

func newROLayerForImage(img *image.Image, layerStore layer.Store) (builder.ROLayer, error) {
    if img == nil || img.RootFS.ChainID() == "" {
        return &roLayer{layerStore: layerStore}, nil
    }
    // Hold a reference to the image layer so that it can't be removed before
    // it is released
    lyr, err := layerStore.Get(img.RootFS.ChainID())
    if err != nil {
        return nil, errors.Wrapf(err, "failed to get layer for image %s", img.ImageID())
    }
    return &roLayer{layerStore: layerStore, roLayer: lyr}, nil
}

// TODO: could this use the regular daemon PullImage ?
func (i *ImageService) pullForBuilder(ctx context.Context, name string, authConfigs map[string]registry.AuthConfig, output io.Writer, platform *ocispec.Platform) (*image.Image, error) {
    ref, err := reference.ParseNormalizedNamed(name)
    if err != nil {
        return nil, err
    }
    ref = reference.TagNameOnly(ref)

    pullRegistryAuth := &registry.AuthConfig{}
    if len(authConfigs) > 0 {
        // The request came with a full auth config, use it
        repoInfo, err := i.registryService.ResolveRepository(ref)
        if err != nil {
            return nil, err
        }

        resolvedConfig := registrypkg.ResolveAuthConfig(authConfigs, repoInfo.Index)
        pullRegistryAuth = &resolvedConfig
    }

    if err := i.pullImageWithReference(ctx, ref, platform, nil, pullRegistryAuth, output); err != nil {
        return nil, err
    }

    img, err := i.GetImage(ctx, name, backend.GetImageOpts{Platform: platform})
    if errdefs.IsNotFound(err) && img != nil && platform != nil {
        imgPlat := ocispec.Platform{
            OS:           img.OS,
            Architecture: img.BaseImgArch(),
            Variant:      img.BaseImgVariant(),
        }

        p := *platform
        if !platforms.Only(p).Match(imgPlat) {
            po := streamformatter.NewJSONProgressOutput(output, false)
            progress.Messagef(po, "", `
WARNING: Pulled image with specified platform (%s), but the resulting image's configured platform (%s) does not match.
This is most likely caused by a bug in the build system that created the fetched image (%s).
Please notify the image author to correct the configuration.`,
                platforms.Format(p), platforms.Format(imgPlat), name,
            )
            log.G(ctx).WithError(err).WithField("image", name).Warn("Ignoring error about platform mismatch where the manifest list points to an image whose configuration does not match the platform in the manifest.")
            err = nil
        }
    }
    return img, err
}

// GetImageAndReleasableLayer returns an image and releaseable layer for a reference or ID.
// Every call to GetImageAndReleasableLayer MUST call releasableLayer.Release() to prevent
// leaking of layers.
func (i *ImageService) GetImageAndReleasableLayer(ctx context.Context, refOrID string, opts backend.GetImageAndLayerOptions) (builder.Image, builder.ROLayer, error) {
    if refOrID == "" { // FROM scratch
        if runtime.GOOS == "windows" {
            return nil, nil, fmt.Errorf(`"FROM scratch" is not supported on Windows`)
        }
        if opts.Platform != nil {
            if err := image.CheckOS(opts.Platform.OS); err != nil {
                return nil, nil, err
            }
        }
        lyr, err := newROLayerForImage(nil, i.layerStore)
        return nil, lyr, err
    }

    if opts.PullOption != backend.PullOptionForcePull {
        img, err := i.GetImage(ctx, refOrID, backend.GetImageOpts{Platform: opts.Platform})
        if err != nil && opts.PullOption == backend.PullOptionNoPull {
            return nil, nil, err
        }
        if err != nil && !errdefs.IsNotFound(err) {
            return nil, nil, err
        }
        if img != nil {
            if err := image.CheckOS(img.OperatingSystem()); err != nil {
                return nil, nil, err
            }
            lyr, err := newROLayerForImage(img, i.layerStore)
            return img, lyr, err
        }
    }

    img, err := i.pullForBuilder(ctx, refOrID, opts.AuthConfig, opts.Output, opts.Platform)
    if err != nil {
        return nil, nil, err
    }
    if err := image.CheckOS(img.OperatingSystem()); err != nil {
        return nil, nil, err
    }
    lyr, err := newROLayerForImage(img, i.layerStore)
    return img, lyr, err
}

// CreateImage creates a new image by adding a config and ID to the image store.
// This is similar to LoadImage() except that it receives JSON encoded bytes of
// an image instead of a tar archive.
func (i *ImageService) CreateImage(ctx context.Context, config []byte, parent string, _ digest.Digest) (builder.Image, error) {
    id, err := i.imageStore.Create(config)
    if err != nil {
        return nil, errors.Wrapf(err, "failed to create image")
    }

    if parent != "" {
        if err := i.imageStore.SetParent(id, image.ID(parent)); err != nil {
            return nil, errors.Wrapf(err, "failed to set parent %s", parent)
        }
    }
    if err := i.imageStore.SetBuiltLocally(id); err != nil {
        return nil, errors.Wrapf(err, "failed to mark image %s as built locally", id)
    }

    return i.imageStore.Get(id)
}