containerd/services/diff/service.go
Stephen J Day 8508e8252b
plugin: refactor plugin system to support initialization reporting
Signed-off-by: Stephen J Day <stephen.day@docker.com>
2017-10-10 16:40:47 -07:00

131 lines
3.0 KiB
Go

package diff
import (
diffapi "github.com/containerd/containerd/api/services/diff/v1"
"github.com/containerd/containerd/api/types"
"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"`
}
func init() {
plugin.Register(&plugin.Registration{
Type: plugin.GRPCPlugin,
ID: "diff",
Requires: []plugin.Type{
plugin.DiffPlugin,
},
Config: &config{
Order: []string{"walking"},
},
InitFn: func(ic *plugin.InitContext) (interface{}, error) {
differs, err := ic.GetByType(plugin.DiffPlugin)
if err != nil {
return nil, err
}
orderedNames := ic.Config.(*config).Order
ordered := make([]plugin.Differ, len(orderedNames))
for i, n := range orderedNames {
differp, ok := differs[n]
if !ok {
return nil, errors.Errorf("needed differ not loaded: %s", n)
}
differ, err := differp.Instance()
if err != nil {
return nil, errors.Wrapf(err, "could not load required differ due plugin init error: %s", n)
}
ordered[i] = differ.(plugin.Differ)
}
return &service{
differs: ordered,
}, nil
},
})
}
type service struct {
differs []plugin.Differ
}
func (s *service) Register(gs *grpc.Server) error {
diffapi.RegisterDiffServer(gs, s)
return nil
}
func (s *service) Apply(ctx context.Context, er *diffapi.ApplyRequest) (*diffapi.ApplyResponse, error) {
var (
ocidesc ocispec.Descriptor
err error
desc = toDescriptor(er.Diff)
mounts = toMounts(er.Mounts)
)
for _, differ := range s.differs {
ocidesc, err = differ.Apply(ctx, desc, mounts)
if !errdefs.IsNotImplemented(err) {
break
}
}
if err != nil {
return nil, errdefs.ToGRPC(err)
}
return &diffapi.ApplyResponse{
Applied: fromDescriptor(ocidesc),
}, nil
}
func (s *service) Diff(ctx context.Context, dr *diffapi.DiffRequest) (*diffapi.DiffResponse, error) {
var (
ocidesc ocispec.Descriptor
err error
aMounts = toMounts(dr.Left)
bMounts = toMounts(dr.Right)
)
for _, differ := range s.differs {
ocidesc, err = differ.DiffMounts(ctx, aMounts, bMounts, dr.MediaType, dr.Ref)
if !errdefs.IsNotImplemented(err) {
break
}
}
if err != nil {
return nil, errdefs.ToGRPC(err)
}
return &diffapi.DiffResponse{
Diff: fromDescriptor(ocidesc),
}, nil
}
func toMounts(apim []*types.Mount) []mount.Mount {
mounts := make([]mount.Mount, len(apim))
for i, m := range apim {
mounts[i] = mount.Mount{
Type: m.Type,
Source: m.Source,
Options: m.Options,
}
}
return mounts
}