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converter: Allow hooks during image conversion

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This commit allows hook callbacks during image conversion.
This enbles the caller additional modification for each blob descriptor.

Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com>
This commit is contained in:
Kohei Tokunaga 2021-10-29 17:18:58 +09:00
parent aa65faebd7
commit f0d3ea96cf
1 changed files with 32 additions and 0 deletions
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32
images/converter/default.go
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@ -48,12 +48,35 @@ func DefaultIndexConvertFunc(layerConvertFunc ConvertFunc, docker2oci bool, plat
return c.convert
}
// ConvertHookFunc is a callback function called during conversion of a blob.
// orgDesc is the target descriptor to convert. newDesc is passed if conversion happens.
type ConvertHookFunc func(ctx context.Context, cs content.Store, orgDesc ocispec.Descriptor, newDesc *ocispec.Descriptor) (*ocispec.Descriptor, error)
// ConvertHooks is a configuration for hook callbacks called during blob conversion.
type ConvertHooks struct {
// PostConvertHook is a callback function called for each blob after conversion is done.
PostConvertHook ConvertHookFunc
}
// IndexConvertFuncWithHook is the convert func used by Convert with hook functions support.
func IndexConvertFuncWithHook(layerConvertFunc ConvertFunc, docker2oci bool, platformMC platforms.MatchComparer, hooks ConvertHooks) ConvertFunc {
c := &defaultConverter{
layerConvertFunc: layerConvertFunc,
docker2oci: docker2oci,
platformMC: platformMC,
diffIDMap: make(map[digest.Digest]digest.Digest),
hooks: hooks,
}
return c.convert
}
type defaultConverter struct {
layerConvertFunc ConvertFunc
docker2oci bool
platformMC platforms.MatchComparer
diffIDMap map[digest.Digest]digest.Digest // key: old diffID, value: new diffID
diffIDMapMu sync.RWMutex
hooks ConvertHooks
}
// convert dispatches desc.MediaType and calls c.convert{Layer,Manifest,Index,Config}.
@ -76,6 +99,15 @@ func (c *defaultConverter) convert(ctx context.Context, cs content.Store, desc o
if err != nil {
return nil, err
}
if c.hooks.PostConvertHook != nil {
if newDescPost, err := c.hooks.PostConvertHook(ctx, cs, desc, newDesc); err != nil {
return nil, err
} else if newDescPost != nil {
newDesc = newDescPost
}
}
if images.IsDockerType(desc.MediaType) {
if c.docker2oci {
if newDesc == nil {