@@ -19,7 +19,7 @@ type Backend interface {

 	GetServices(basictypes.ServiceListOptions) ([]types.Service, error)

 	GetService(string) (types.Service, error)

 	CreateService(types.ServiceSpec, string) (*basictypes.ServiceCreateResponse, error)

-	UpdateService(string, uint64, types.ServiceSpec, string, string) (*basictypes.ServiceUpdateResponse, error)

+	UpdateService(string, uint64, types.ServiceSpec, basictypes.ServiceUpdateOptions) (*basictypes.ServiceUpdateResponse, error)

 	RemoveService(string) error

 	ServiceLogs(context.Context, string, *backend.ContainerLogsConfig, chan struct{}) error

 	GetNodes(basictypes.NodeListOptions) ([]types.Node, error)

@@ -192,12 +192,14 @@ func (sr *swarmRouter) updateService(ctx context.Context, w http.ResponseWriter,

 		return errors.NewBadRequestError(err)

 	}

-	// Get returns "" if the header does not exist

-	encodedAuth := r.Header.Get("X-Registry-Auth")

+	var flags basictypes.ServiceUpdateOptions

-	registryAuthFrom := r.URL.Query().Get("registryAuthFrom")

+	// Get returns "" if the header does not exist

+	flags.EncodedRegistryAuth = r.Header.Get("X-Registry-Auth")

+	flags.RegistryAuthFrom = r.URL.Query().Get("registryAuthFrom")

+	flags.Rollback = r.URL.Query().Get("rollback")

-	resp, err := sr.backend.UpdateService(vars["id"], version, service, encodedAuth, registryAuthFrom)

+	resp, err := sr.backend.UpdateService(vars["id"], version, service, flags)

 	if err != nil {

 		logrus.Errorf("Error updating service %s: %v", vars["id"], err)

 		return err

@@ -7631,6 +7631,12 @@ paths:

   parameter indicates where to find registry authorization credentials. The

   valid values are `spec` and `previous-spec`."

           default: "spec"

+        - name: "rollback"

+          in: "query"

+          type: "string"

+          description: "Set to this parameter to `previous` to cause a

+  server-side rollback to the previous service spec. The supplied spec will be

+  ignored in this case."

         - name: "X-Registry-Auth"

           in: "header"

           description: "A base64-encoded auth configuration for pulling from private registries. [See the authentication section for details.](#section/Authentication)"

@@ -320,6 +320,12 @@ type ServiceUpdateOptions struct {

 	// credentials if they are not given in EncodedRegistryAuth. Valid

 	// values are "spec" and "previous-spec".

 	RegistryAuthFrom string

+

+	// Rollback indicates whether a server-side rollback should be

+	// performed. When this is set, the provided spec will be ignored.

+	// The valid values are "previous" and "none". An empty value is the

+	// same as "none".

+	Rollback string

 }

 // ServiceListOptions holds parameters to list  services with.

@@ -1,6 +1,7 @@

 package service

 import (

+	"errors"

 	"fmt"

 	"sort"

 	"strings"

@@ -10,6 +11,7 @@ import (

 	"github.com/docker/docker/api/types/container"

 	mounttypes "github.com/docker/docker/api/types/mount"

 	"github.com/docker/docker/api/types/swarm"

+	"github.com/docker/docker/api/types/versions"

 	"github.com/docker/docker/cli"

 	"github.com/docker/docker/cli/command"

 	"github.com/docker/docker/client"

@@ -95,7 +97,6 @@ func newListOptsVar() *opts.ListOpts {

 func runUpdate(dockerCli *command.DockerCli, flags *pflag.FlagSet, serviceID string) error {

 	apiClient := dockerCli.Client()

 	ctx := context.Background()

-	updateOpts := types.ServiceUpdateOptions{}

 	service, _, err := apiClient.ServiceInspectWithRaw(ctx, serviceID)

 	if err != nil {

@@ -107,12 +108,44 @@ func runUpdate(dockerCli *command.DockerCli, flags *pflag.FlagSet, serviceID str

 		return err

 	}

+	// There are two ways to do user-requested rollback. The old way is

+	// client-side, but with a sufficiently recent daemon we prefer

+	// server-side, because it will honor the rollback parameters.

+	var (

+		clientSideRollback bool

+		serverSideRollback bool

+	)

+

 	spec := &service.Spec

 	if rollback {

-		spec = service.PreviousSpec

-		if spec == nil {

-			return fmt.Errorf("service does not have a previous specification to roll back to")

+		// Rollback can't be combined with other flags.

+		otherFlagsPassed := false

+		flags.VisitAll(func(f *pflag.Flag) {

+			if f.Name == "rollback" {

+				return

+			}

+			if flags.Changed(f.Name) {

+				otherFlagsPassed = true

+			}

+		})

+		if otherFlagsPassed {

+			return errors.New("other flags may not be combined with --rollback")

 		}

+

+		if versions.LessThan(dockerCli.Client().ClientVersion(), "1.27") {

+			clientSideRollback = true

+			spec = service.PreviousSpec

+			if spec == nil {

+				return fmt.Errorf("service does not have a previous specification to roll back to")

+			}

+		} else {

+			serverSideRollback = true

+		}

+	}

+

+	updateOpts := types.ServiceUpdateOptions{}

+	if serverSideRollback {

+		updateOpts.Rollback = "previous"

 	}

 	err = updateService(flags, spec)

@@ -147,7 +180,7 @@ func runUpdate(dockerCli *command.DockerCli, flags *pflag.FlagSet, serviceID str

 			return err

 		}

 		updateOpts.EncodedRegistryAuth = encodedAuth

-	} else if rollback {

+	} else if clientSideRollback {

 		updateOpts.RegistryAuthFrom = types.RegistryAuthFromPreviousSpec

 	} else {

 		updateOpts.RegistryAuthFrom = types.RegistryAuthFromSpec

@@ -27,6 +27,10 @@ func (cli *Client) ServiceUpdate(ctx context.Context, serviceID string, version

 		query.Set("registryAuthFrom", options.RegistryAuthFrom)

 	}

+	if options.Rollback != "" {

+		query.Set("rollback", options.Rollback)

+	}

+

 	query.Set("version", strconv.FormatUint(version.Index, 10))

 	var response types.ServiceUpdateResponse

@@ -176,7 +176,7 @@ func ServiceSpecToGRPC(s types.ServiceSpec) (swarmapi.ServiceSpec, error) {

 	}

 	spec.Rollback, err = updateConfigToGRPC(s.RollbackConfig)

 	if err != nil {

-		return swarmapi.Servicepec{}, err

+		return swarmapi.ServiceSpec{}, err

 	}

 	if s.EndpointSpec != nil {

@@ -132,7 +132,7 @@ func (c *Cluster) CreateService(s types.ServiceSpec, encodedAuth string) (*apity

 }

 // UpdateService updates existing service to match new properties.

-func (c *Cluster) UpdateService(serviceIDOrName string, version uint64, spec types.ServiceSpec, encodedAuth string, registryAuthFrom string) (*apitypes.ServiceUpdateResponse, error) {

+func (c *Cluster) UpdateService(serviceIDOrName string, version uint64, spec types.ServiceSpec, flags apitypes.ServiceUpdateOptions) (*apitypes.ServiceUpdateResponse, error) {

 	var resp *apitypes.ServiceUpdateResponse

 	err := c.lockedManagerAction(func(ctx context.Context, state nodeState) error {

@@ -157,13 +157,14 @@ func (c *Cluster) UpdateService(serviceIDOrName string, version uint64, spec typ

 			return errors.New("service does not use container tasks")

 		}

+		encodedAuth := flags.EncodedRegistryAuth

 		if encodedAuth != "" {

 			newCtnr.PullOptions = &swarmapi.ContainerSpec_PullOptions{RegistryAuth: encodedAuth}

 		} else {

 			// this is needed because if the encodedAuth isn't being updated then we

 			// shouldn't lose it, and continue to use the one that was already present

 			var ctnr *swarmapi.ContainerSpec

-			switch registryAuthFrom {

+			switch flags.RegistryAuthFrom {

 			case apitypes.RegistryAuthFromSpec, "":

 				ctnr = currentService.Spec.Task.GetContainer()

 			case apitypes.RegistryAuthFromPreviousSpec:

@@ -208,6 +209,16 @@ func (c *Cluster) UpdateService(serviceIDOrName string, version uint64, spec typ

 			}

 		}

+		var rollback swarmapi.UpdateServiceRequest_Rollback

+		switch flags.Rollback {

+		case "", "none":

+			rollback = swarmapi.UpdateServiceRequest_NONE

+		case "previous":

+			rollback = swarmapi.UpdateServiceRequest_PREVIOUS

+		default:

+			return fmt.Errorf("unrecognized rollback option %s", flags.Rollback)

+		}

+

 		_, err = state.controlClient.UpdateService(

 			ctx,

 			&swarmapi.UpdateServiceRequest{

@@ -216,6 +227,7 @@ func (c *Cluster) UpdateService(serviceIDOrName string, version uint64, spec typ

 				ServiceVersion: &swarmapi.Version{

 					Index: version,

 				},

+				Rollback: rollback,

 			},

 		)

 		return err

@@ -138,6 +138,7 @@ func (s *DockerSwarmSuite) TestAPISwarmServicesUpdate(c *check.C) {

 	// create service

 	instances := 5

 	parallelism := 2

+	rollbackParallelism := 3

 	id := daemons[0].CreateService(c, serviceForUpdate, setInstances(instances))

 	// wait for tasks ready

@@ -161,20 +162,16 @@ func (s *DockerSwarmSuite) TestAPISwarmServicesUpdate(c *check.C) {

 		map[string]int{image2: instances})

 	// Roll back to the previous version. This uses the CLI because

-	// rollback is a client-side operation.

+	// rollback used to be a client-side operation.

 	out, err := daemons[0].Cmd("service", "update", "--rollback", id)

 	c.Assert(err, checker.IsNil, check.Commentf(out))

 	// first batch

 	waitAndAssert(c, defaultReconciliationTimeout, daemons[0].CheckRunningTaskImages, checker.DeepEquals,

-		map[string]int{image2: instances - parallelism, image1: parallelism})

+		map[string]int{image2: instances - rollbackParallelism, image1: rollbackParallelism})

 	// 2nd batch

 	waitAndAssert(c, defaultReconciliationTimeout, daemons[0].CheckRunningTaskImages, checker.DeepEquals,

-		map[string]int{image2: instances - 2*parallelism, image1: 2 * parallelism})

-

-	// 3nd batch

-	waitAndAssert(c, defaultReconciliationTimeout, daemons[0].CheckRunningTaskImages, checker.DeepEquals,

 		map[string]int{image1: instances})

 }

@@ -210,7 +207,7 @@ func (s *DockerSwarmSuite) TestAPISwarmServicesFailedUpdate(c *check.C) {

 	c.Assert(v, checker.Equals, instances-2)

 	// Roll back to the previous version. This uses the CLI because

-	// rollback is a client-side operation.

+	// rollback used to be a client-side operation.

 	out, err := daemons[0].Cmd("service", "update", "--rollback", id)

 	c.Assert(err, checker.IsNil, check.Commentf(out))

@@ -556,6 +556,11 @@ func serviceForUpdate(s *swarm.Service) {

 			Delay:         4 * time.Second,

 			FailureAction: swarm.UpdateFailureActionContinue,

 		},

+		RollbackConfig: &swarm.UpdateConfig{

+			Parallelism:   3,

+			Delay:         4 * time.Second,

+			FailureAction: swarm.UpdateFailureActionContinue,

+		},

 	}

 	s.Spec.Name = "updatetest"

 }