Add leases api

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

services/leases/service.go

@@ -0,0 +1,115 @@
+package leases
+
+import (
+	"crypto/rand"
+	"encoding/base64"
+	"fmt"
+	"time"
+
+	"google.golang.org/grpc"
+
+	"github.com/boltdb/bolt"
+	api "github.com/containerd/containerd/api/services/leases/v1"
+	"github.com/containerd/containerd/metadata"
+	"github.com/containerd/containerd/plugin"
+	"github.com/golang/protobuf/ptypes/empty"
+	"golang.org/x/net/context"
+)
+
+func init() {
+	plugin.Register(&plugin.Registration{
+		Type: plugin.GRPCPlugin,
+		ID:   "leases",
+		Requires: []plugin.Type{
+			plugin.MetadataPlugin,
+		},
+		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
+			m, err := ic.Get(plugin.MetadataPlugin)
+			if err != nil {
+				return nil, err
+			}
+			return NewService(m.(*metadata.DB)), nil
+		},
+	})
+}
+
+type service struct {
+	db *metadata.DB
+}
+
+// NewService returns the GRPC metadata server
+func NewService(db *metadata.DB) api.LeasesServer {
+	return &service{
+		db: db,
+	}
+}
+
+func (s *service) Register(server *grpc.Server) error {
+	api.RegisterLeasesServer(server, s)
+	return nil
+}
+
+func (s *service) Create(ctx context.Context, r *api.CreateRequest) (*api.CreateResponse, error) {
+	lid := r.ID
+	if lid == "" {
+		lid = generateLeaseID()
+	}
+	var trans metadata.Lease
+	if err := s.db.Update(func(tx *bolt.Tx) error {
+		var err error
+		trans, err = metadata.NewLeaseManager(tx).Create(ctx, lid, r.Labels)
+		return err
+	}); err != nil {
+		return nil, err
+	}
+	return &api.CreateResponse{
+		Lease: txToGRPC(trans),
+	}, nil
+}
+
+func (s *service) Delete(ctx context.Context, r *api.DeleteRequest) (*empty.Empty, error) {
+	if err := s.db.Update(func(tx *bolt.Tx) error {
+		return metadata.NewLeaseManager(tx).Delete(ctx, r.ID)
+	}); err != nil {
+		return nil, err
+	}
+	return &empty.Empty{}, nil
+}
+
+func (s *service) List(ctx context.Context, r *api.ListRequest) (*api.ListResponse, error) {
+	var leases []metadata.Lease
+	if err := s.db.View(func(tx *bolt.Tx) error {
+		var err error
+		leases, err = metadata.NewLeaseManager(tx).List(ctx, false, r.Filters...)
+		return err
+	}); err != nil {
+		return nil, err
+	}
+
+	apileases := make([]*api.Lease, len(leases))
+	for i := range leases {
+		apileases[i] = txToGRPC(leases[i])
+	}
+
+	return &api.ListResponse{
+		Leases: apileases,
+	}, nil
+}
+
+func txToGRPC(tx metadata.Lease) *api.Lease {
+	return &api.Lease{
+		ID:        tx.ID,
+		Labels:    tx.Labels,
+		CreatedAt: tx.CreatedAt,
+		// TODO: Snapshots
+		// TODO: Content
+	}
+}
+
+func generateLeaseID() string {
+	t := time.Now()
+	var b [3]byte
+	// Ignore read failures, just decreases uniqueness
+	rand.Read(b[:])
+	return fmt.Sprintf("%d-%s", t.Nanosecond(), base64.URLEncoding.EncodeToString(b[:]))
+}