add app reservation (#284)

app/handler/app.go

@@ -0,0 +1,119 @@
+package handler
+
+import (
+	"context"
+	"crypto/sha1"
+	"fmt"
+	"io"
+	"regexp"
+	"sync"
+	"time"
+
+	"github.com/micro/micro/v3/service/errors"
+	"github.com/micro/micro/v3/service/store"
+	pb "github.com/micro/services/app/proto"
+	"github.com/micro/services/pkg/tenant"
+)
+
+type App struct{}
+
+var (
+	mtx sync.Mutex
+
+	ReservationKey = "reservedApp/"
+	NameFormat     = regexp.MustCompilePOSIX("[a-z0-9]+")
+)
+
+type Reservation struct {
+	// The app name
+	Name string `json:"name"`
+	// The owner e.g tenant id
+	Owner string `json:"owner"`
+	// Uniq associated token
+	Token string `json:"token"`
+	// Time of creation
+	Created time.Time `json:"created"`
+	// The expiry time
+	Expires time.Time `json:"expires"`
+}
+
+func genToken(name, owner string) string {
+	h := sha1.New()
+	io.WriteString(h, name+owner)
+	return fmt.Sprintf("%x", h.Sum(nil))
+}
+
+// Call is a single request handler called via client.Call or the generated client code
+func (a *App) Reserve(ctx context.Context, req *pb.ReserveRequest, rsp *pb.ReserveResponse) error {
+	id, ok := tenant.FromContext(ctx)
+	if !ok {
+		id = "micro"
+	}
+
+	if len(req.Name) == 0 {
+		return errors.BadRequest("app.reserve", "missing app name")
+	}
+
+	if len(req.Name) < 3 || len(req.Name) > 256 {
+		return errors.BadRequest("app.reserve", "name must be longer than 3-256 chars in length")
+	}
+
+	if !NameFormat.MatchString(req.Name) {
+		return errors.BadRequest("app.reserve", "invalidate name format")
+	}
+
+	// to prevent race conditions in reservation lets global lock
+	mtx.Lock()
+	defer mtx.Unlock()
+
+	// check the store for reservation
+	recs, err := store.Read(ReservationKey + req.Name)
+	if err != nil && err != store.ErrNotFound {
+		return errors.InternalServerError("app.reserve", "failed to reserve name")
+	}
+
+	var rsrv *Reservation
+
+	// check if the record exists
+	if len(recs) > 0 {
+		// existing reservation exists
+		rec := recs[0]
+
+		if err := rec.Decode(&rsrv); err != nil {
+			return errors.BadRequest("app.reserve", "name already reserved")
+		}
+
+		// check the owner matches
+		if rsrv.Owner != id {
+			return errors.BadRequest("app.reserve", "name already reserved")
+		}
+
+		// update the reservation
+		rsrv.Expires = time.Now().AddDate(1, 0, 0)
+	} else {
+		// not reserved
+		rsrv = &Reservation{
+			Name:    req.Name,
+			Owner:   id,
+			Created: time.Now(),
+			Expires: time.Now().AddDate(1, 0, 0),
+			Token:   genToken(req.Name, id),
+		}
+	}
+
+	rec := store.NewRecord(ReservationKey+req.Name, rsrv)
+
+	if err := store.Write(rec); err != nil {
+		return errors.InternalServerError("app.reserve", "error while reserving name")
+	}
+
+	rsp.Reservation = &pb.Reservation{
+		Name:    rsrv.Name,
+		Owner:   rsrv.Owner,
+		Created: rsrv.Created.Format(time.RFC3339Nano),
+		Expires: rsrv.Expires.Format(time.RFC3339Nano),
+		Token:   rsrv.Token,
+	}
+
+	return nil
+}