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daemon/list: Refactor refreshImage

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Add context comments and make it a bit more readable.

Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>
(cherry picked from commit 68991ae240)
Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>
This commit is contained in:
Paweł Gronowski 2023-07-26 13:20:20 +02:00
parent fcb68e55fa
commit 6c4121a943
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GPG key ID: B85EFCFE26DEF92A
1 changed files with 61 additions and 12 deletions
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73
daemon/list.go
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@ -578,21 +578,70 @@ func includeContainerInList(container *container.Snapshot, filter *listContext)
return includeContainer
}
// refreshImage checks if the Image ref still points to the correct ID, and updates the ref to the actual ID when it doesn't
// refreshImage checks if the Image ref still points to the correct ID, and
// updates the ref to the actual ID when it doesn't.
// This happens when the image with a reference that was used to create
// container was deleted or updated and now resolves to a different ID.
//
// For example:
// $ docker run -d busybox:latest
// $ docker ps -a
// CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
// b0318bca5aef busybox "sh" 4 seconds ago Exited (0) 3 seconds ago ecstatic_beaver
//
// After some time, busybox image got updated on the Docker Hub:
// $ docker pull busybox:latest
//
// So now busybox:latest points to a different digest, but that doesn't impact
// the ecstatic_beaver container which was still created under an older
// version. In this case, it should still point to the original image ID it was
// created from.
//
// $ docker ps -a
// CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
// b0318bca5aef 3fbc63216742 "sh" 3 years ago Exited (0) 3 years ago ecstatic_beaver
func (daemon *Daemon) refreshImage(ctx context.Context, s *container.Snapshot, filter *listContext) (*types.Container, error) {
c := s.Container
tmpImage := s.Image // keep the original ref if still valid (hasn't changed)
if tmpImage != s.ImageID {
img, err := daemon.imageService.GetImage(ctx, tmpImage, imagetypes.GetImageOpts{})
if err != nil && !errdefs.IsNotFound(err) {
return nil, err
}
if err != nil || img.ImageID() != s.ImageID {
// ref changed, we need to use original ID
tmpImage = s.ImageID
}
// s.Image is the image reference passed by the user to create an image
// can be a:
// - name (like nginx, ubuntu:latest, docker.io/library/busybox:latest),
// - truncated ID (abcdef),
// - full digest (sha256:abcdef...)
//
// s.ImageID is the ID of the image that s.Image resolved to at the time
// of the container creation. It's always a full digest.
// If these match, there's nothing to refresh.
if s.Image == s.ImageID {
return &c, nil
}
c.Image = tmpImage
// Check if the image reference still resolves to the same digest.
img, err := daemon.imageService.GetImage(ctx, s.Image, imagetypes.GetImageOpts{})
// If the image is no longer found or can't be resolved for some other
// reason. Update the Image to the specific ID of the original image it
// resolved to when the container was created.
if err != nil {
if !errdefs.IsNotFound(err) {
logrus.WithFields(logrus.Fields{
logrus.ErrorKey: err,
"containerID": c.ID,
"image": s.Image,
"imageID": s.ImageID,
}).Warn("failed to resolve container image")
}
c.Image = s.ImageID
return &c, nil
}
// Also update the image to the specific image ID, if the Image now
// resolves to a different ID.
if img.ImageID() != s.ImageID {
c.Image = s.ImageID
}
return &c, nil
}