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Add support for multiple differs

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Updates the differ service to support calling and configuring
multiple differs. The differs are configured as an ordered list
of differs which will each be attempting until a supported differ
is called.

Additionally a not supported error type was added to allow differs
to be selective of whether the differ arguments are supported by
the differ. This error type corresponds to the GRPC unimplemented error.

Signed-off-by: Derek McGowan <derek@mcgstyle.net>
This commit is contained in:
Derek McGowan 2017-08-18 11:19:08 -07:00
parent b2ee0ab34e
commit 2fa366d6af
No known key found for this signature in database
GPG Key ID: F58C5D0A4405ACDB
4 changed files with 98 additions and 29 deletions
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49
differ/differ.go
View File

@ -4,11 +4,14 @@ import (
"io"
"io/ioutil"
"os"
"strings"
"github.com/boltdb/bolt"
"github.com/containerd/containerd/archive"
"github.com/containerd/containerd/archive/compression"
"github.com/containerd/containerd/content"
"github.com/containerd/containerd/errdefs"
"github.com/containerd/containerd/images"
"github.com/containerd/containerd/metadata"
"github.com/containerd/containerd/mount"
"github.com/containerd/containerd/plugin"
@ -21,7 +24,7 @@ import (
func init() {
plugin.Register(&plugin.Registration{
Type: plugin.DiffPlugin,
ID: "base-diff",
ID: "walking",
Requires: []plugin.PluginType{
plugin.ContentPlugin,
plugin.MetadataPlugin,
@ -35,27 +38,38 @@ func init() {
if err != nil {
return nil, err
}
return NewBaseDiff(metadata.NewContentStore(md.(*bolt.DB), c.(content.Store)))
return newWalkingDiff(metadata.NewContentStore(md.(*bolt.DB), c.(content.Store)))
},
})
}
type BaseDiff struct {
type walkingDiff struct {
store content.Store
}
var _ plugin.Differ = &BaseDiff{}
var emptyDesc = ocispec.Descriptor{}
func NewBaseDiff(store content.Store) (*BaseDiff, error) {
return &BaseDiff{
func newWalkingDiff(store content.Store) (plugin.Differ, error) {
return &walkingDiff{
store: store,
}, nil
}
func (s *BaseDiff) Apply(ctx context.Context, desc ocispec.Descriptor, mounts []mount.Mount) (ocispec.Descriptor, error) {
// TODO: Check for supported media types
func (s *walkingDiff) Apply(ctx context.Context, desc ocispec.Descriptor, mounts []mount.Mount) (ocispec.Descriptor, error) {
var isCompressed bool
switch desc.MediaType {
case ocispec.MediaTypeImageLayer, images.MediaTypeDockerSchema2Layer:
case ocispec.MediaTypeImageLayerGzip, images.MediaTypeDockerSchema2LayerGzip:
isCompressed = true
default:
// Still apply all generic media types *.tar[.+]gzip and *.tar
if strings.HasSuffix(desc.MediaType, ".tar.gzip") || strings.HasSuffix(desc.MediaType, ".tar+gzip") {
isCompressed = true
} else if !strings.HasSuffix(desc.MediaType, ".tar") {
return emptyDesc, errors.Wrapf(errdefs.ErrNotSupported, "unsupported diff media type: %v", desc.MediaType)
}
}
dir, err := ioutil.TempDir("", "extract-")
if err != nil {
return emptyDesc, errors.Wrap(err, "failed to create temporary directory")
@ -67,22 +81,25 @@ func (s *BaseDiff) Apply(ctx context.Context, desc ocispec.Descriptor, mounts []
}
defer mount.Unmount(dir, 0)
r, err := s.store.ReaderAt(ctx, desc.Digest)
ra, err := s.store.ReaderAt(ctx, desc.Digest)
if err != nil {
return emptyDesc, errors.Wrap(err, "failed to get reader from content store")
}
defer r.Close()
defer ra.Close()
// TODO: only decompress stream if media type is compressed
ds, err := compression.DecompressStream(content.NewReader(r))
r := content.NewReader(ra)
if isCompressed {
ds, err := compression.DecompressStream(r)
if err != nil {
return emptyDesc, err
}
defer ds.Close()
r = ds
}
digester := digest.Canonical.Digester()
rc := &readCounter{
r: io.TeeReader(ds, digester.Hash()),
r: io.TeeReader(r, digester.Hash()),
}
if _, err := archive.Apply(ctx, dir, rc); err != nil {
@ -101,7 +118,7 @@ func (s *BaseDiff) Apply(ctx context.Context, desc ocispec.Descriptor, mounts []
}, nil
}
func (s *BaseDiff) DiffMounts(ctx context.Context, lower, upper []mount.Mount, media, ref string) (ocispec.Descriptor, error) {
func (s *walkingDiff) DiffMounts(ctx context.Context, lower, upper []mount.Mount, media, ref string) (ocispec.Descriptor, error) {
var isCompressed bool
switch media {
case ocispec.MediaTypeImageLayer:
@ -111,7 +128,7 @@ func (s *BaseDiff) DiffMounts(ctx context.Context, lower, upper []mount.Mount, m
media = ocispec.MediaTypeImageLayerGzip
isCompressed = true
default:
return emptyDesc, errors.Errorf("unsupported diff media type: %v", media)
return emptyDesc, errors.Wrapf(errdefs.ErrNotSupported, "unsupported diff media type: %v", media)
}
aDir, err := ioutil.TempDir("", "left-")
if err != nil {

5
errdefs/errors.go
View File

@ -26,6 +26,7 @@ var (
ErrAlreadyExists = errors.New("already exists")
ErrFailedPrecondition = errors.New("failed precondition")
ErrUnavailable = errors.New("unavailable")
ErrNotSupported = errors.New("not supported") // represents not supported and unimplemented
)
func IsInvalidArgument(err error) bool {
@ -52,3 +53,7 @@ func IsFailedPrecondition(err error) bool {
func IsUnavailable(err error) bool {
return errors.Cause(err) == ErrUnavailable
}
func IsNotSupported(err error) bool {
return errors.Cause(err) == ErrNotSupported
}

4
errdefs/grpc.go
View File

@ -38,6 +38,8 @@ func ToGRPC(err error) error {
return grpc.Errorf(codes.FailedPrecondition, err.Error())
case IsUnavailable(err):
return grpc.Errorf(codes.Unavailable, err.Error())
case IsNotSupported(err):
return grpc.Errorf(codes.Unimplemented, err.Error())
}
return err
@ -69,6 +71,8 @@ func FromGRPC(err error) error {
cls = ErrUnavailable
case codes.FailedPrecondition:
cls = ErrFailedPrecondition
case codes.Unimplemented:
cls = ErrNotSupported
default:
cls = ErrUnknown
}

63
services/diff/service.go
View File

@ -6,10 +6,22 @@ import (
"github.com/containerd/containerd/errdefs"
"github.com/containerd/containerd/mount"
"github.com/containerd/containerd/plugin"
ocispec "github.com/opencontainers/image-spec/specs-go/v1"
"github.com/pkg/errors"
"golang.org/x/net/context"
"google.golang.org/grpc"
)
type config struct {
// Order is the order of preference in which to try diff algorithms, the
// first differ which is supported is used.
// Note when multiple differs may be supported, this order will be
// respected for which is choosen. Each differ should return the same
// correct output, allowing any ordering to be used to prefer
// more optimimal implementations.
Order []string `toml:"default,omitempty"`
}
func init() {
plugin.Register(&plugin.Registration{
Type: plugin.GRPCPlugin,
@ -17,20 +29,34 @@ func init() {
Requires: []plugin.PluginType{
plugin.DiffPlugin,
},
Config: &config{
Order: []string{"walking"},
},
Init: func(ic *plugin.InitContext) (interface{}, error) {
d, err := ic.Get(plugin.DiffPlugin)
differs, err := ic.GetAll(plugin.DiffPlugin)
if err != nil {
return nil, err
}
orderedNames := ic.Config.(*config).Order
ordered := make([]plugin.Differ, len(orderedNames))
for i, n := range orderedNames {
differ, ok := differs[n]
if !ok {
return nil, errors.Errorf("needed differ not loaded: %s", n)
}
ordered[i] = differ.(plugin.Differ)
}
return &service{
diff: d.(plugin.Differ),
differs: ordered,
}, nil
},
})
}
type service struct {
diff plugin.Differ
differs []plugin.Differ
}
func (s *service) Register(gs *grpc.Server) error {
@ -39,12 +65,20 @@ func (s *service) Register(gs *grpc.Server) error {
}
func (s *service) Apply(ctx context.Context, er *diffapi.ApplyRequest) (*diffapi.ApplyResponse, error) {
desc := toDescriptor(er.Diff)
// TODO: Check for supported media types
var (
ocidesc ocispec.Descriptor
err error
desc = toDescriptor(er.Diff)
mounts = toMounts(er.Mounts)
)
mounts := toMounts(er.Mounts)
for _, differ := range s.differs {
ocidesc, err = differ.Apply(ctx, desc, mounts)
if !errdefs.IsNotSupported(err) {
break
}
}
ocidesc, err := s.diff.Apply(ctx, desc, mounts)
if err != nil {
return nil, errdefs.ToGRPC(err)
}
@ -56,10 +90,19 @@ func (s *service) Apply(ctx context.Context, er *diffapi.ApplyRequest) (*diffapi
}
func (s *service) Diff(ctx context.Context, dr *diffapi.DiffRequest) (*diffapi.DiffResponse, error) {
aMounts := toMounts(dr.Left)
bMounts := toMounts(dr.Right)
var (
ocidesc ocispec.Descriptor
err error
aMounts = toMounts(dr.Left)
bMounts = toMounts(dr.Right)
)
ocidesc, err := s.diff.DiffMounts(ctx, aMounts, bMounts, dr.MediaType, dr.Ref)
for _, differ := range s.differs {
ocidesc, err = differ.DiffMounts(ctx, aMounts, bMounts, dr.MediaType, dr.Ref)
if !errdefs.IsNotSupported(err) {
break
}
}
if err != nil {
return nil, errdefs.ToGRPC(err)
}