package daemon import ( "fmt" "strings" "github.com/docker/docker/api/types" "github.com/docker/docker/container" derr "github.com/docker/docker/errors" "github.com/docker/docker/image" "github.com/docker/docker/pkg/stringid" "github.com/docker/docker/reference" ) // ImageDelete deletes the image referenced by the given imageRef from this // daemon. The given imageRef can be an image ID, ID prefix, or a repository // reference (with an optional tag or digest, defaulting to the tag name // "latest"). There is differing behavior depending on whether the given // imageRef is a repository reference or not. // // If the given imageRef is a repository reference then that repository // reference will be removed. However, if there exists any containers which // were created using the same image reference then the repository reference // cannot be removed unless either there are other repository references to the // same image or force is true. Following removal of the repository reference, // the referenced image itself will attempt to be deleted as described below // but quietly, meaning any image delete conflicts will cause the image to not // be deleted and the conflict will not be reported. // // There may be conflicts preventing deletion of an image and these conflicts // are divided into two categories grouped by their severity: // // Hard Conflict: // - a pull or build using the image. // - any descendent image. // - any running container using the image. // // Soft Conflict: // - any stopped container using the image. // - any repository tag or digest references to the image. // // The image cannot be removed if there are any hard conflicts and can be // removed if there are soft conflicts only if force is true. // // If prune is true, ancestor images will each attempt to be deleted quietly, // meaning any delete conflicts will cause the image to not be deleted and the // conflict will not be reported. // // FIXME: remove ImageDelete's dependency on Daemon, then move to the graph // package. This would require that we no longer need the daemon to determine // whether images are being used by a stopped or running container. func (daemon *Daemon) ImageDelete(imageRef string, force, prune bool) ([]types.ImageDelete, error) { records := []types.ImageDelete{} imgID, err := daemon.GetImageID(imageRef) if err != nil { return nil, daemon.imageNotExistToErrcode(err) } repoRefs := daemon.referenceStore.References(imgID) var removedRepositoryRef bool if !isImageIDPrefix(imgID.String(), imageRef) { // A repository reference was given and should be removed // first. We can only remove this reference if either force is // true, there are multiple repository references to this // image, or there are no containers using the given reference. if !(force || len(repoRefs) > 1) { if container := daemon.getContainerUsingImage(imgID); container != nil { // If we removed the repository reference then // this image would remain "dangling" and since // we really want to avoid that the client must // explicitly force its removal. return nil, derr.ErrorCodeImgDelUsed.WithArgs(imageRef, stringid.TruncateID(container.ID), stringid.TruncateID(imgID.String())) } } parsedRef, err := reference.ParseNamed(imageRef) if err != nil { return nil, err } parsedRef, err = daemon.removeImageRef(parsedRef) if err != nil { return nil, err } untaggedRecord := types.ImageDelete{Untagged: parsedRef.String()} daemon.EventsService.Log("untag", imgID.String(), "") records = append(records, untaggedRecord) // If has remaining references then untag finishes the remove if len(repoRefs) > 1 { return records, nil } removedRepositoryRef = true } else { // If an ID reference was given AND there is exactly one // repository reference to the image then we will want to // remove that reference. // FIXME: Is this the behavior we want? if len(repoRefs) == 1 { parsedRef, err := daemon.removeImageRef(repoRefs[0]) if err != nil { return nil, err } untaggedRecord := types.ImageDelete{Untagged: parsedRef.String()} daemon.EventsService.Log("untag", imgID.String(), "") records = append(records, untaggedRecord) } } return records, daemon.imageDeleteHelper(imgID, &records, force, prune, removedRepositoryRef) } // isImageIDPrefix returns whether the given possiblePrefix is a prefix of the // given imageID. func isImageIDPrefix(imageID, possiblePrefix string) bool { if strings.HasPrefix(imageID, possiblePrefix) { return true } if i := strings.IndexRune(imageID, ':'); i >= 0 { return strings.HasPrefix(imageID[i+1:], possiblePrefix) } return false } // getContainerUsingImage returns a container that was created using the given // imageID. Returns nil if there is no such container. func (daemon *Daemon) getContainerUsingImage(imageID image.ID) *container.Container { for _, container := range daemon.List() { if container.ImageID == imageID { return container } } return nil } // removeImageRef attempts to parse and remove the given image reference from // this daemon's store of repository tag/digest references. The given // repositoryRef must not be an image ID but a repository name followed by an // optional tag or digest reference. If tag or digest is omitted, the default // tag is used. Returns the resolved image reference and an error. func (daemon *Daemon) removeImageRef(ref reference.Named) (reference.Named, error) { ref = reference.WithDefaultTag(ref) // Ignore the boolean value returned, as far as we're concerned, this // is an idempotent operation and it's okay if the reference didn't // exist in the first place. _, err := daemon.referenceStore.Delete(ref) return ref, err } // removeAllReferencesToImageID attempts to remove every reference to the given // imgID from this daemon's store of repository tag/digest references. Returns // on the first encountered error. Removed references are logged to this // daemon's event service. An "Untagged" types.ImageDelete is added to the // given list of records. func (daemon *Daemon) removeAllReferencesToImageID(imgID image.ID, records *[]types.ImageDelete) error { imageRefs := daemon.referenceStore.References(imgID) for _, imageRef := range imageRefs { parsedRef, err := daemon.removeImageRef(imageRef) if err != nil { return err } untaggedRecord := types.ImageDelete{Untagged: parsedRef.String()} daemon.EventsService.Log("untag", imgID.String(), "") *records = append(*records, untaggedRecord) } return nil } // ImageDeleteConflict holds a soft or hard conflict and an associated error. // Implements the error interface. type imageDeleteConflict struct { hard bool used bool imgID image.ID message string } func (idc *imageDeleteConflict) Error() string { var forceMsg string if idc.hard { forceMsg = "cannot be forced" } else { forceMsg = "must be forced" } return fmt.Sprintf("conflict: unable to delete %s (%s) - %s", stringid.TruncateID(idc.imgID.String()), forceMsg, idc.message) } // imageDeleteHelper attempts to delete the given image from this daemon. If // the image has any hard delete conflicts (child images or running containers // using the image) then it cannot be deleted. If the image has any soft delete // conflicts (any tags/digests referencing the image or any stopped container // using the image) then it can only be deleted if force is true. If the delete // succeeds and prune is true, the parent images are also deleted if they do // not have any soft or hard delete conflicts themselves. Any deleted images // and untagged references are appended to the given records. If any error or // conflict is encountered, it will be returned immediately without deleting // the image. If quiet is true, any encountered conflicts will be ignored and // the function will return nil immediately without deleting the image. func (daemon *Daemon) imageDeleteHelper(imgID image.ID, records *[]types.ImageDelete, force, prune, quiet bool) error { // First, determine if this image has any conflicts. Ignore soft conflicts // if force is true. if conflict := daemon.checkImageDeleteConflict(imgID, force); conflict != nil { if quiet && (!daemon.imageIsDangling(imgID) || conflict.used) { // Ignore conflicts UNLESS the image is "dangling" or not being used in // which case we want the user to know. return nil } // There was a conflict and it's either a hard conflict OR we are not // forcing deletion on soft conflicts. return conflict } parent, err := daemon.imageStore.GetParent(imgID) if err != nil { // There may be no parent parent = "" } // Delete all repository tag/digest references to this image. if err := daemon.removeAllReferencesToImageID(imgID, records); err != nil { return err } removedLayers, err := daemon.imageStore.Delete(imgID) if err != nil { return err } daemon.EventsService.Log("delete", imgID.String(), "") *records = append(*records, types.ImageDelete{Deleted: imgID.String()}) for _, removedLayer := range removedLayers { *records = append(*records, types.ImageDelete{Deleted: removedLayer.ChainID.String()}) } if !prune || parent == "" { return nil } // We need to prune the parent image. This means delete it if there are // no tags/digests referencing it and there are no containers using it ( // either running or stopped). // Do not force prunings, but do so quietly (stopping on any encountered // conflicts). return daemon.imageDeleteHelper(parent, records, false, true, true) } // checkImageDeleteConflict determines whether there are any conflicts // preventing deletion of the given image from this daemon. A hard conflict is // any image which has the given image as a parent or any running container // using the image. A soft conflict is any tags/digest referencing the given // image or any stopped container using the image. If ignoreSoftConflicts is // true, this function will not check for soft conflict conditions. func (daemon *Daemon) checkImageDeleteConflict(imgID image.ID, ignoreSoftConflicts bool) *imageDeleteConflict { // Check for hard conflicts first. if conflict := daemon.checkImageDeleteHardConflict(imgID); conflict != nil { return conflict } // Then check for soft conflicts. if ignoreSoftConflicts { // Don't bother checking for soft conflicts. return nil } return daemon.checkImageDeleteSoftConflict(imgID) } func (daemon *Daemon) checkImageDeleteHardConflict(imgID image.ID) *imageDeleteConflict { // Check if the image has any descendent images. if len(daemon.imageStore.Children(imgID)) > 0 { return &imageDeleteConflict{ hard: true, imgID: imgID, message: "image has dependent child images", } } // Check if any running container is using the image. for _, container := range daemon.List() { if !container.IsRunning() { // Skip this until we check for soft conflicts later. continue } if container.ImageID == imgID { return &imageDeleteConflict{ imgID: imgID, hard: true, used: true, message: fmt.Sprintf("image is being used by running container %s", stringid.TruncateID(container.ID)), } } } return nil } func (daemon *Daemon) checkImageDeleteSoftConflict(imgID image.ID) *imageDeleteConflict { // Check if any repository tags/digest reference this image. if len(daemon.referenceStore.References(imgID)) > 0 { return &imageDeleteConflict{ imgID: imgID, message: "image is referenced in one or more repositories", } } // Check if any stopped containers reference this image. for _, container := range daemon.List() { if container.IsRunning() { // Skip this as it was checked above in hard conflict conditions. continue } if container.ImageID == imgID { return &imageDeleteConflict{ imgID: imgID, used: true, message: fmt.Sprintf("image is being used by stopped container %s", stringid.TruncateID(container.ID)), } } } return nil } // imageIsDangling returns whether the given image is "dangling" which means // that there are no repository references to the given image and it has no // child images. func (daemon *Daemon) imageIsDangling(imgID image.ID) bool { return !(len(daemon.referenceStore.References(imgID)) > 0 || len(daemon.imageStore.Children(imgID)) > 0) }