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Merge pull request #1148 from mtrmac/create-incomplete
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(Alternative to 1140): Record layers as incomplete before trying to create them
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@rhatdan
rhatdan committed May 2, 2022
2 parents f6fd87f + 70cd76b commit 512d612
Showing 1 changed file with 88 additions and 100 deletions.
188 changes: 88 additions & 100 deletions layers.go
View file
Expand Up @@ -692,11 +692,10 @@ func (r *layerStore) PutAdditionalLayer(id string, parentLayer *Layer, names []s
return copyLayer(layer), nil
}

func (r *layerStore) Put(id string, parentLayer *Layer, names []string, mountLabel string, options map[string]string, moreOptions *LayerOptions, writeable bool, flags map[string]interface{}, diff io.Reader) (layer *Layer, size int64, err error) {
func (r *layerStore) Put(id string, parentLayer *Layer, names []string, mountLabel string, options map[string]string, moreOptions *LayerOptions, writeable bool, flags map[string]interface{}, diff io.Reader) (*Layer, int64, error) {
if !r.IsReadWrite() {
return nil, -1, errors.Wrapf(ErrStoreIsReadOnly, "not allowed to create new layers at %q", r.layerspath())
}
size = -1
if err := os.MkdirAll(r.rundir, 0700); err != nil {
return nil, -1, err
}
Expand Down Expand Up @@ -762,139 +761,128 @@ func (r *layerStore) Put(id string, parentLayer *Layer, names []string, mountLab
if mountLabel != "" {
label.ReserveLabel(mountLabel)
}

// Before actually creating the layer, make a persistent record of it with incompleteFlag,
// so that future processes have a chance to delete it.
layer := &Layer{
ID: id,
Parent: parent,
Names: names,
MountLabel: mountLabel,
Metadata: templateMetadata,
Created: time.Now().UTC(),
CompressedDigest: templateCompressedDigest,
CompressedSize: templateCompressedSize,
UncompressedDigest: templateUncompressedDigest,
UncompressedSize: templateUncompressedSize,
CompressionType: templateCompressionType,
UIDs: templateUIDs,
GIDs: templateGIDs,
Flags: make(map[string]interface{}),
UIDMap: copyIDMap(moreOptions.UIDMap),
GIDMap: copyIDMap(moreOptions.GIDMap),
BigDataNames: []string{},
}
r.layers = append(r.layers, layer)
r.idindex.Add(id)
r.byid[id] = layer
for _, name := range names {
r.byname[name] = layer
}
for flag, value := range flags {
layer.Flags[flag] = value
}
layer.Flags[incompleteFlag] = true

succeeded := false
cleanupFailureContext := ""
defer func() {
if !succeeded {
// On any error, try both removing the driver's data as well
// as the in-memory layer record.
if err2 := r.Delete(layer.ID); err2 != nil {
if cleanupFailureContext == "" {
cleanupFailureContext = "unknown: cleanupFailureContext not set at the failure site"
}
logrus.Errorf("While recovering from a failure (%s), error deleting layer %#v: %v", cleanupFailureContext, layer.ID, err2)
}
}
}()

err := r.Save()
if err != nil {
cleanupFailureContext = "saving incomplete layer metadata"
return nil, -1, err
}

idMappings := idtools.NewIDMappingsFromMaps(moreOptions.UIDMap, moreOptions.GIDMap)
opts := drivers.CreateOpts{
MountLabel: mountLabel,
StorageOpt: options,
IDMappings: idMappings,
}
if moreOptions.TemplateLayer != "" {
if err = r.driver.CreateFromTemplate(id, moreOptions.TemplateLayer, templateIDMappings, parent, parentMappings, &opts, writeable); err != nil {
if err := r.driver.CreateFromTemplate(id, moreOptions.TemplateLayer, templateIDMappings, parent, parentMappings, &opts, writeable); err != nil {
cleanupFailureContext = "creating a layer from template"
return nil, -1, errors.Wrapf(err, "error creating copy of template layer %q with ID %q", moreOptions.TemplateLayer, id)
}
oldMappings = templateIDMappings
} else {
if writeable {
if err = r.driver.CreateReadWrite(id, parent, &opts); err != nil {
if err := r.driver.CreateReadWrite(id, parent, &opts); err != nil {
cleanupFailureContext = "creating a read-write layer"
return nil, -1, errors.Wrapf(err, "error creating read-write layer with ID %q", id)
}
} else {
if err = r.driver.Create(id, parent, &opts); err != nil {
if err := r.driver.Create(id, parent, &opts); err != nil {
cleanupFailureContext = "creating a read-only layer"
return nil, -1, errors.Wrapf(err, "error creating layer with ID %q", id)
}
}
oldMappings = parentMappings
}
if !reflect.DeepEqual(oldMappings.UIDs(), idMappings.UIDs()) || !reflect.DeepEqual(oldMappings.GIDs(), idMappings.GIDs()) {
if err = r.driver.UpdateLayerIDMap(id, oldMappings, idMappings, mountLabel); err != nil {
// We don't have a record of this layer, but at least
// try to clean it up underneath us.
if err2 := r.driver.Remove(id); err2 != nil {
logrus.Errorf("While recovering from a failure creating in UpdateLayerIDMap, error deleting layer %#v: %v", id, err2)
}
if err := r.driver.UpdateLayerIDMap(id, oldMappings, idMappings, mountLabel); err != nil {
cleanupFailureContext = "in UpdateLayerIDMap"
return nil, -1, err
}
}
if len(templateTSdata) > 0 {
if err := os.MkdirAll(filepath.Dir(r.tspath(id)), 0o700); err != nil {
// We don't have a record of this layer, but at least
// try to clean it up underneath us.
if err2 := r.driver.Remove(id); err2 != nil {
logrus.Errorf("While recovering from a failure creating in UpdateLayerIDMap, error deleting layer %#v: %v", id, err2)
}
cleanupFailureContext = "creating tar-split parent directory for a copy from template"
return nil, -1, err
}
if err = ioutils.AtomicWriteFile(r.tspath(id), templateTSdata, 0o600); err != nil {
// We don't have a record of this layer, but at least
// try to clean it up underneath us.
if err2 := r.driver.Remove(id); err2 != nil {
logrus.Errorf("While recovering from a failure creating in UpdateLayerIDMap, error deleting layer %#v: %v", id, err2)
}
if err := ioutils.AtomicWriteFile(r.tspath(id), templateTSdata, 0o600); err != nil {
cleanupFailureContext = "creating a tar-split copy from template"
return nil, -1, err
}
}
if err == nil {
layer = &Layer{
ID: id,
Parent: parent,
Names: names,
MountLabel: mountLabel,
Metadata: templateMetadata,
Created: time.Now().UTC(),
CompressedDigest: templateCompressedDigest,
CompressedSize: templateCompressedSize,
UncompressedDigest: templateUncompressedDigest,
UncompressedSize: templateUncompressedSize,
CompressionType: templateCompressionType,
UIDs: templateUIDs,
GIDs: templateGIDs,
Flags: make(map[string]interface{}),
UIDMap: copyIDMap(moreOptions.UIDMap),
GIDMap: copyIDMap(moreOptions.GIDMap),
BigDataNames: []string{},
}
r.layers = append(r.layers, layer)
r.idindex.Add(id)
r.byid[id] = layer
for _, name := range names {
r.byname[name] = layer
}
for flag, value := range flags {
layer.Flags[flag] = value
}
savedIncompleteLayer := false
if diff != nil {
layer.Flags[incompleteFlag] = true
err = r.Save()
if err != nil {
// We don't have a record of this layer, but at least
// try to clean it up underneath us.
if err2 := r.driver.Remove(id); err2 != nil {
logrus.Errorf("While recovering from a failure saving incomplete layer metadata, error deleting layer %#v: %v", id, err2)
}
return nil, -1, err
}
savedIncompleteLayer = true
size, err = r.applyDiffWithOptions(layer.ID, moreOptions, diff)
if err != nil {
if err2 := r.Delete(layer.ID); err2 != nil {
// Either a driver error or an error saving.
// We now have a layer that's been marked for
// deletion but which we failed to remove.
logrus.Errorf("While recovering from a failure applying layer diff, error deleting layer %#v: %v", layer.ID, err2)
}
return nil, -1, err
}
delete(layer.Flags, incompleteFlag)
} else {
// applyDiffWithOptions in the `diff != nil` case handles this bit for us
if layer.CompressedDigest != "" {
r.bycompressedsum[layer.CompressedDigest] = append(r.bycompressedsum[layer.CompressedDigest], layer.ID)
}
if layer.UncompressedDigest != "" {
r.byuncompressedsum[layer.UncompressedDigest] = append(r.byuncompressedsum[layer.UncompressedDigest], layer.ID)
}
}
err = r.Save()

var size int64 = -1
if diff != nil {
size, err = r.applyDiffWithOptions(layer.ID, moreOptions, diff)
if err != nil {
if savedIncompleteLayer {
if err2 := r.Delete(layer.ID); err2 != nil {
// Either a driver error or an error saving.
// We now have a layer that's been marked for
// deletion but which we failed to remove.
logrus.Errorf("While recovering from a failure saving finished layer metadata, error deleting layer %#v: %v", layer.ID, err2)
}
} else {
// We don't have a record of this layer, but at least
// try to clean it up underneath us.
if err2 := r.driver.Remove(id); err2 != nil {
logrus.Errorf("While recovering from a failure saving finished layer metadata, error deleting layer %#v in graph driver: %v", id, err2)
}
}
cleanupFailureContext = "applying layer diff"
return nil, -1, err
}
layer = copyLayer(layer)
} else {
// applyDiffWithOptions in the `diff != nil` case handles this bit for us
if layer.CompressedDigest != "" {
r.bycompressedsum[layer.CompressedDigest] = append(r.bycompressedsum[layer.CompressedDigest], layer.ID)
}
if layer.UncompressedDigest != "" {
r.byuncompressedsum[layer.UncompressedDigest] = append(r.byuncompressedsum[layer.UncompressedDigest], layer.ID)
}
}
delete(layer.Flags, incompleteFlag)
err = r.Save()
if err != nil {
cleanupFailureContext = "saving finished layer metadata"
return nil, -1, err
}

layer = copyLayer(layer)
succeeded = true
return layer, size, err
}

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