package client

import (
	"encoding/json"
	"net/url"
	"strconv"

	"github.com/docker/docker/api/types"
	"github.com/docker/docker/api/types/swarm"
	"golang.org/x/net/context"
)

// ServiceUpdate updates a Service.
func (cli *Client) ServiceUpdate(ctx context.Context, serviceID string, version swarm.Version, service swarm.ServiceSpec, options types.ServiceUpdateOptions) (types.ServiceUpdateResponse, error) {
	var (
		headers map[string][]string
		query   = url.Values{}
	)

	if options.EncodedRegistryAuth != "" {
		headers = map[string][]string{
			"X-Registry-Auth": {options.EncodedRegistryAuth},
		}
	}

	if options.RegistryAuthFrom != "" {
		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
	resp, err := cli.post(ctx, "/services/"+serviceID+"/update", query, service, headers)
	if err != nil {
		return response, err
	}

	err = json.NewDecoder(resp.body).Decode(&response)
	ensureReaderClosed(resp)
	return response, err
}

package client

import (
	"encoding/json"
	"net/url"
	"strconv"

	"github.com/docker/docker/api/types"
	"github.com/docker/docker/api/types/swarm"
	"golang.org/x/net/context"
)

// ServiceUpdate updates a Service.
func (cli *Client) ServiceUpdate(ctx context.Context, serviceID string, version swarm.Version, service swarm.ServiceSpec, options types.ServiceUpdateOptions) (types.ServiceUpdateResponse, error) {
	var (
		headers map[string][]string
		query   = url.Values{}
	)

	if options.EncodedRegistryAuth != "" {
		headers = map[string][]string{
			"X-Registry-Auth": {options.EncodedRegistryAuth},
		}
	}

	if options.RegistryAuthFrom != "" {
		query.Set("registryAuthFrom", options.RegistryAuthFrom)
	}

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

	var response types.ServiceUpdateResponse
	resp, err := cli.post(ctx, "/services/"+serviceID+"/update", query, service, headers)
	if err != nil {
		return response, err
	}

	err = json.NewDecoder(resp.body).Decode(&response)
	ensureReaderClosed(resp)
	return response, err
}

--- 
+++ 
@@ -27,6 +27,10 @@
 		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
Implement server-side rollback, for daemon versions that support this

Server-side rollback can take advantage of the rollback-specific update
parameters, instead of being treated as a normal update that happens to
go back to a previous version of the spec.

Signed-off-by: Aaron Lehmann <8ecfc6017a87905413dcd7d63696a2a4c351b604@docker.com>
