Document plugins

Add plugins documentation to root.
Mention configuring proxy plugins and runtime plugins.

Signed-off-by: Derek McGowan <derek@mcgstyle.net>

contrib/snapshotservice/service.go

@@ -0,0 +1,218 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package snapshotservice
+
+import (
+	"context"
+
+	snapshotsapi "github.com/containerd/containerd/api/services/snapshots/v1"
+	"github.com/containerd/containerd/api/types"
+	"github.com/containerd/containerd/errdefs"
+	"github.com/containerd/containerd/mount"
+	"github.com/containerd/containerd/snapshots"
+	ptypes "github.com/gogo/protobuf/types"
+)
+
+var empty = &ptypes.Empty{}
+
+type service struct {
+	sn snapshots.Snapshotter
+}
+
+// FromSnapshotter returns a Snapshot API server from a containerd snapshotter
+func FromSnapshotter(sn snapshots.Snapshotter) snapshotsapi.SnapshotsServer {
+	return service{sn: sn}
+}
+
+func (s service) Prepare(ctx context.Context, pr *snapshotsapi.PrepareSnapshotRequest) (*snapshotsapi.PrepareSnapshotResponse, error) {
+	var opts []snapshots.Opt
+	if pr.Labels != nil {
+		opts = append(opts, snapshots.WithLabels(pr.Labels))
+	}
+	mounts, err := s.sn.Prepare(ctx, pr.Key, pr.Parent, opts...)
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+
+	return &snapshotsapi.PrepareSnapshotResponse{
+		Mounts: fromMounts(mounts),
+	}, nil
+}
+
+func (s service) View(ctx context.Context, pr *snapshotsapi.ViewSnapshotRequest) (*snapshotsapi.ViewSnapshotResponse, error) {
+	var opts []snapshots.Opt
+	if pr.Labels != nil {
+		opts = append(opts, snapshots.WithLabels(pr.Labels))
+	}
+	mounts, err := s.sn.View(ctx, pr.Key, pr.Parent, opts...)
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+	return &snapshotsapi.ViewSnapshotResponse{
+		Mounts: fromMounts(mounts),
+	}, nil
+}
+
+func (s service) Mounts(ctx context.Context, mr *snapshotsapi.MountsRequest) (*snapshotsapi.MountsResponse, error) {
+	mounts, err := s.sn.Mounts(ctx, mr.Key)
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+	return &snapshotsapi.MountsResponse{
+		Mounts: fromMounts(mounts),
+	}, nil
+}
+
+func (s service) Commit(ctx context.Context, cr *snapshotsapi.CommitSnapshotRequest) (*ptypes.Empty, error) {
+	var opts []snapshots.Opt
+	if cr.Labels != nil {
+		opts = append(opts, snapshots.WithLabels(cr.Labels))
+	}
+	if err := s.sn.Commit(ctx, cr.Name, cr.Key, opts...); err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+
+	return empty, nil
+}
+
+func (s service) Remove(ctx context.Context, rr *snapshotsapi.RemoveSnapshotRequest) (*ptypes.Empty, error) {
+	if err := s.sn.Remove(ctx, rr.Key); err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+
+	return empty, nil
+}
+
+func (s service) Stat(ctx context.Context, sr *snapshotsapi.StatSnapshotRequest) (*snapshotsapi.StatSnapshotResponse, error) {
+	info, err := s.sn.Stat(ctx, sr.Key)
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+
+	return &snapshotsapi.StatSnapshotResponse{Info: fromInfo(info)}, nil
+}
+
+func (s service) Update(ctx context.Context, sr *snapshotsapi.UpdateSnapshotRequest) (*snapshotsapi.UpdateSnapshotResponse, error) {
+	info, err := s.sn.Update(ctx, toInfo(sr.Info), sr.UpdateMask.GetPaths()...)
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+
+	return &snapshotsapi.UpdateSnapshotResponse{Info: fromInfo(info)}, nil
+}
+
+func (s service) List(sr *snapshotsapi.ListSnapshotsRequest, ss snapshotsapi.Snapshots_ListServer) error {
+	var (
+		buffer    []snapshotsapi.Info
+		sendBlock = func(block []snapshotsapi.Info) error {
+			return ss.Send(&snapshotsapi.ListSnapshotsResponse{
+				Info: block,
+			})
+		}
+	)
+	err := s.sn.Walk(ss.Context(), func(ctx context.Context, info snapshots.Info) error {
+		buffer = append(buffer, fromInfo(info))
+
+		if len(buffer) >= 100 {
+			if err := sendBlock(buffer); err != nil {
+				return err
+			}
+
+			buffer = buffer[:0]
+		}
+
+		return nil
+	})
+	if err != nil {
+		return err
+	}
+	if len(buffer) > 0 {
+		// Send remaining infos
+		if err := sendBlock(buffer); err != nil {
+			return err
+		}
+	}
+
+	return nil
+
+}
+
+func (s service) Usage(ctx context.Context, ur *snapshotsapi.UsageRequest) (*snapshotsapi.UsageResponse, error) {
+	usage, err := s.sn.Usage(ctx, ur.Key)
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+
+	return &snapshotsapi.UsageResponse{
+		Inodes: usage.Inodes,
+		Size_:  usage.Size,
+	}, nil
+}
+
+func fromKind(kind snapshots.Kind) snapshotsapi.Kind {
+	if kind == snapshots.KindActive {
+		return snapshotsapi.KindActive
+	}
+	if kind == snapshots.KindView {
+		return snapshotsapi.KindView
+	}
+	return snapshotsapi.KindCommitted
+}
+
+func fromInfo(info snapshots.Info) snapshotsapi.Info {
+	return snapshotsapi.Info{
+		Name:      info.Name,
+		Parent:    info.Parent,
+		Kind:      fromKind(info.Kind),
+		CreatedAt: info.Created,
+		UpdatedAt: info.Updated,
+		Labels:    info.Labels,
+	}
+}
+
+func fromMounts(mounts []mount.Mount) []*types.Mount {
+	out := make([]*types.Mount, len(mounts))
+	for i, m := range mounts {
+		out[i] = &types.Mount{
+			Type:    m.Type,
+			Source:  m.Source,
+			Options: m.Options,
+		}
+	}
+	return out
+}
+
+func toInfo(info snapshotsapi.Info) snapshots.Info {
+	return snapshots.Info{
+		Name:    info.Name,
+		Parent:  info.Parent,
+		Kind:    toKind(info.Kind),
+		Created: info.CreatedAt,
+		Updated: info.UpdatedAt,
+		Labels:  info.Labels,
+	}
+}
+
+func toKind(kind snapshotsapi.Kind) snapshots.Kind {
+	if kind == snapshotsapi.KindActive {
+		return snapshots.KindActive
+	}
+	if kind == snapshotsapi.KindView {
+		return snapshots.KindView
+	}
+	return snapshots.KindCommitted
+}