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moby--moby/daemon/image_delete.go

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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)
}