commit.go

package buildah

import (
	"context"
	"fmt"
	"io"
	"io/ioutil"
	"time"

	cp "github.com/containers/image/copy"
	"github.com/containers/image/signature"
	is "github.com/containers/image/storage"
	"github.com/containers/image/transports"
	"github.com/containers/image/types"
	"github.com/containers/storage"
	"github.com/containers/storage/pkg/archive"
	"github.com/pkg/errors"
	"github.com/projectatomic/buildah/util"
	"github.com/sirupsen/logrus"
)

// CommitOptions can be used to alter how an image is committed.
type CommitOptions struct {
	// PreferredManifestType is the preferred type of image manifest.  The
	// image configuration format will be of a compatible type.
	PreferredManifestType string
	// Compression specifies the type of compression which is applied to
	// layer blobs.  The default is to not use compression, but
	// archive.Gzip is recommended.
	Compression archive.Compression
	// SignaturePolicyPath specifies an override location for the signature
	// policy which should be used for verifying the new image as it is
	// being written.  Except in specific circumstances, no value should be
	// specified, indicating that the shared, system-wide default policy
	// should be used.
	SignaturePolicyPath string
	// AdditionalTags is a list of additional names to add to the image, if
	// the transport to which we're writing the image gives us a way to add
	// them.
	AdditionalTags []string
	// ReportWriter is an io.Writer which will be used to log the writing
	// of the new image.
	ReportWriter io.Writer
	// HistoryTimestamp is the timestamp used when creating new items in the
	// image's history.  If unset, the current time will be used.
	HistoryTimestamp *time.Time
	// github.com/containers/image/types SystemContext to hold credentials
	// and other authentication/authorization information.
	SystemContext *types.SystemContext
	// IIDFile tells the builder to write the image ID to the specified file
	IIDFile string
	// Squash tells the builder to produce an image with a single layer
	// instead of with possibly more than one layer.
	Squash bool

	// OnBuild is a list of commands to be run by images based on this image
	OnBuild []string
	// Parent is the base image that this image was created by.
	Parent string
}

// PushOptions can be used to alter how an image is copied somewhere.
type PushOptions struct {
	// Compression specifies the type of compression which is applied to
	// layer blobs.  The default is to not use compression, but
	// archive.Gzip is recommended.
	Compression archive.Compression
	// SignaturePolicyPath specifies an override location for the signature
	// policy which should be used for verifying the new image as it is
	// being written.  Except in specific circumstances, no value should be
	// specified, indicating that the shared, system-wide default policy
	// should be used.
	SignaturePolicyPath string
	// ReportWriter is an io.Writer which will be used to log the writing
	// of the new image.
	ReportWriter io.Writer
	// Store is the local storage store which holds the source image.
	Store storage.Store
	// github.com/containers/image/types SystemContext to hold credentials
	// and other authentication/authorization information.
	SystemContext *types.SystemContext
	// ManifestType is the format to use when saving the imge using the 'dir' transport
	// possible options are oci, v2s1, and v2s2
	ManifestType string
}

// Commit writes the contents of the container, along with its updated
// configuration, to a new image in the specified location, and if we know how,
// add any additional tags that were specified. Returns the ID of the new image
// if commit was successful and the image destination was local
func (b *Builder) Commit(ctx context.Context, dest types.ImageReference, options CommitOptions) (string, error) {
	var imgID string

	systemContext := getSystemContext(options.SystemContext, options.SignaturePolicyPath)
	policy, err := signature.DefaultPolicy(systemContext)
	if err != nil {
		return imgID, errors.Wrapf(err, "error obtaining default signature policy")
	}
	policyContext, err := signature.NewPolicyContext(policy)
	if err != nil {
		return imgID, errors.Wrapf(err, "error creating new signature policy context")
	}
	defer func() {
		if err2 := policyContext.Destroy(); err2 != nil {
			logrus.Debugf("error destroying signature policy context: %v", err2)
		}
	}()
	// Check if the base image is already in the destination and it's some kind of local
	// storage.  If so, we can skip recompressing any layers that come from the base image.
	exportBaseLayers := true
	if transport, destIsStorage := dest.Transport().(is.StoreTransport); destIsStorage && b.FromImageID != "" {
		if baseref, err := transport.ParseReference(b.FromImageID); baseref != nil && err == nil {
			if img, err := transport.GetImage(baseref); img != nil && err == nil {
				exportBaseLayers = false
			}
		}
	}
	src, err := b.makeImageRef(options.PreferredManifestType, options.Parent, exportBaseLayers, options.Squash, options.Compression, options.HistoryTimestamp)
	if err != nil {
		return imgID, errors.Wrapf(err, "error computing layer digests and building metadata")
	}
	// "Copy" our image to where it needs to be.
	err = cp.Image(ctx, policyContext, dest, src, getCopyOptions(options.ReportWriter, nil, systemContext, ""))
	if err != nil {
		return imgID, errors.Wrapf(err, "error copying layers and metadata")
	}
	if len(options.AdditionalTags) > 0 {
		switch dest.Transport().Name() {
		case is.Transport.Name():
			img, err := is.Transport.GetStoreImage(b.store, dest)
			if err != nil {
				return imgID, errors.Wrapf(err, "error locating just-written image %q", transports.ImageName(dest))
			}
			err = util.AddImageNames(b.store, "", systemContext, img, options.AdditionalTags)
			if err != nil {
				return imgID, errors.Wrapf(err, "error setting image names to %v", append(img.Names, options.AdditionalTags...))
			}
			logrus.Debugf("assigned names %v to image %q", img.Names, img.ID)
		default:
			logrus.Warnf("don't know how to add tags to images stored in %q transport", dest.Transport().Name())
		}
	}

	img, err := is.Transport.GetStoreImage(b.store, dest)
	if err != nil && err != storage.ErrImageUnknown {
		return imgID, err
	}

	if err == nil {
		imgID = img.ID

		if options.IIDFile != "" {
			if err := ioutil.WriteFile(options.IIDFile, []byte(img.ID), 0644); err != nil {
				return imgID, errors.Wrapf(err, "failed to write Image ID File %q", options.IIDFile)
			}
		}
	}

	return imgID, nil
}

// Push copies the contents of the image to a new location.
func Push(ctx context.Context, image string, dest types.ImageReference, options PushOptions) error {
	systemContext := getSystemContext(options.SystemContext, options.SignaturePolicyPath)
	policy, err := signature.DefaultPolicy(systemContext)
	if err != nil {
		return errors.Wrapf(err, "error obtaining default signature policy")
	}
	policyContext, err := signature.NewPolicyContext(policy)
	if err != nil {
		return errors.Wrapf(err, "error creating new signature policy context")
	}
	// Look up the image.
	src, _, err := util.FindImage(options.Store, "", systemContext, image)
	if err != nil {
		return err
	}
	// Copy everything.
	err = cp.Image(ctx, policyContext, dest, src, getCopyOptions(options.ReportWriter, nil, systemContext, options.ManifestType))
	if err != nil {
		return errors.Wrapf(err, "error copying layers and metadata")
	}
	if options.ReportWriter != nil {
		fmt.Fprintf(options.ReportWriter, "\n")
	}
	return nil
}