podman/libpod/diff.go
Adrian Reber 225c7ae6c9
Correctly export the root file-system changes
When doing a checkpoint with --export the root file-system diff was not
working as expected. Instead of getting the changes from the running
container to the highest storage layer it got the changes from the
highest layer to that parent's layer. For a one layer container this
could mean that the complete root file-system is part of the checkpoint.

With this commit this changes to use the same functionality as 'podman
diff'. This actually enables to correctly diff the root file-system
including tracking deleted files.

This also removes the non-working helper functions from libpod/diff.go.

Signed-off-by: Adrian Reber <areber@redhat.com>
2019-12-09 13:29:36 +01:00

80 lines
1.9 KiB
Go

package libpod
import (
"io"
"github.com/containers/libpod/libpod/layers"
"github.com/containers/storage/pkg/archive"
"github.com/pkg/errors"
)
var containerMounts = map[string]bool{
"/dev": true,
"/etc/hostname": true,
"/etc/hosts": true,
"/etc/resolv.conf": true,
"/proc": true,
"/run": true,
"/run/.containerenv": true,
"/run/secrets": true,
"/sys": true,
}
// GetDiff returns the differences between the two images, layers, or containers
func (r *Runtime) GetDiff(from, to string) ([]archive.Change, error) {
toLayer, err := r.getLayerID(to)
if err != nil {
return nil, err
}
fromLayer := ""
if from != "" {
fromLayer, err = r.getLayerID(from)
if err != nil {
return nil, err
}
}
var rchanges []archive.Change
changes, err := r.store.Changes(fromLayer, toLayer)
if err == nil {
for _, c := range changes {
if containerMounts[c.Path] {
continue
}
rchanges = append(rchanges, c)
}
}
return rchanges, err
}
// ApplyDiffTarStream applies the changes stored in 'diff' to the layer 'to'
func (r *Runtime) ApplyDiffTarStream(to string, diff io.Reader) error {
toLayer, err := r.getLayerID(to)
if err != nil {
return err
}
_, err = r.store.ApplyDiff(toLayer, diff)
return err
}
// GetLayerID gets a full layer id given a full or partial id
// If the id matches a container or image, the id of the top layer is returned
// If the id matches a layer, the top layer id is returned
func (r *Runtime) getLayerID(id string) (string, error) {
var toLayer string
toImage, err := r.imageRuntime.NewFromLocal(id)
if err != nil {
toCtr, err := r.store.Container(id)
if err != nil {
toLayer, err = layers.FullID(r.store, id)
if err != nil {
return "", errors.Errorf("layer, image, or container %s does not exist", id)
}
} else {
toLayer = toCtr.LayerID
}
} else {
toLayer = toImage.TopLayer()
}
return toLayer, nil
}