Move lease manager plugin to separate package

Create lease plugin type to separate lease manager from services plugin.
This allows other service plugins to depend on the lease manager.

Signed-off-by: Derek McGowan <derek@mcg.dev>

leases/plugin/local.go

@@ -0,0 +1,82 @@
+/*
+   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 plugin
+
+import (
+	"context"
+
+	"github.com/containerd/containerd/gc"
+	"github.com/containerd/containerd/leases"
+	"github.com/containerd/containerd/metadata"
+	"github.com/containerd/containerd/plugin"
+)
+
+func init() {
+	plugin.Register(&plugin.Registration{
+		Type: plugin.LeasePlugin,
+		ID:   "manager",
+		Requires: []plugin.Type{
+			plugin.MetadataPlugin,
+			plugin.GCPlugin,
+		},
+		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
+			m, err := ic.Get(plugin.MetadataPlugin)
+			if err != nil {
+				return nil, err
+			}
+			g, err := ic.Get(plugin.GCPlugin)
+			if err != nil {
+				return nil, err
+			}
+			return &local{
+				Manager: metadata.NewLeaseManager(m.(*metadata.DB)),
+				gc:      g.(gcScheduler),
+			}, nil
+		},
+	})
+}
+
+type gcScheduler interface {
+	ScheduleAndWait(context.Context) (gc.Stats, error)
+}
+
+type local struct {
+	leases.Manager
+	gc gcScheduler
+}
+
+func (l *local) Delete(ctx context.Context, lease leases.Lease, opts ...leases.DeleteOpt) error {
+	var do leases.DeleteOptions
+	for _, opt := range opts {
+		if err := opt(ctx, &do); err != nil {
+			return err
+		}
+	}
+
+	if err := l.Manager.Delete(ctx, lease); err != nil {
+		return err
+	}
+
+	if do.Synchronous {
+		if _, err := l.gc.ScheduleAndWait(ctx); err != nil {
+			return err
+		}
+	}
+
+	return nil
+
+}