Refactor example/backend

Also promote init function from returning
interface{} to backend.Service to avoid
typecasting

Signed-off-by: Ulysses Souza <ulyssessouza@gmail.com>

azure/backend.go

@@ -22,7 +22,7 @@ import (
 )
 
 func init() {
-	backend.Register("aci", "aci", func(ctx context.Context) (interface{}, error) {
+	backend.Register("aci", "aci", func(ctx context.Context) (backend.Service, error) {
 		return New(ctx)
 	})
 }
@@ -53,11 +53,11 @@ func New(ctx context.Context) (backend.Service, error) {
 
 func getAciAPIService(cgc containerinstance.ContainerGroupsClient, aciCtx store.AciContext) *aciAPIService {
 	return &aciAPIService{
-		container: aciContainerService{
+		aciContainerService: aciContainerService{
 			containerGroupsClient: cgc,
 			ctx:                   aciCtx,
 		},
-		compose: aciComposeService{
+		aciComposeService: aciComposeService{
 			containerGroupsClient: cgc,
 			ctx:                   aciCtx,
 		},
@@ -65,21 +65,21 @@ func getAciAPIService(cgc containerinstance.ContainerGroupsClient, aciCtx store.
 }
 
 type aciAPIService struct {
-	container aciContainerService
-	compose   aciComposeService
+	aciContainerService
+	aciComposeService
 }
 
 func (a *aciAPIService) ContainerService() containers.Service {
 	return &aciContainerService{
-		containerGroupsClient: a.container.containerGroupsClient,
-		ctx:                   a.container.ctx,
+		containerGroupsClient: a.aciContainerService.containerGroupsClient,
+		ctx:                   a.aciContainerService.ctx,
 	}
 }
 
 func (a *aciAPIService) ComposeService() compose.Service {
 	return &aciComposeService{
-		containerGroupsClient: a.compose.containerGroupsClient,
-		ctx:                   a.compose.ctx,
+		containerGroupsClient: a.aciComposeService.containerGroupsClient,
+		ctx:                   a.aciComposeService.ctx,
 	}
 }
 

backend/backend.go

@@ -17,7 +17,7 @@ var (
 	errTypeRegistered = errors.New("backend: already registered")
 )
 
-type initFunc func(context.Context) (interface{}, error)
+type initFunc func(context.Context) (Service, error)
 
 type registeredBackend struct {
 	name        string
@@ -58,7 +58,7 @@ func Register(name string, backendType string, init initFunc) {
 
 // Get returns the backend registered for a particular type, it returns
 // an error if there is no registered backends for the given type.
-func Get(ctx context.Context, backendType string) (interface{}, error) {
+func Get(ctx context.Context, backendType string) (Service, error) {
 	for _, b := range backends.r {
 		if b.backendType == backendType {
 			return b.init(ctx)

client/client.go

@@ -29,7 +29,6 @@ package client
 
 import (
 	"context"
-	"errors"
 
 	"github.com/docker/api/backend"
 	backendv1 "github.com/docker/api/backend/v1"
@@ -53,15 +52,11 @@ func New(ctx context.Context) (*Client, error) {
 	}
 	contextType := s.GetType(cc)
 
-	b, err := backend.Get(ctx, contextType)
+	service, err := backend.Get(ctx, contextType)
 	if err != nil {
 		return nil, err
 	}
 
-	service, ok := b.(backend.Service)
-	if !ok {
-		return nil, errors.New("backend not found")
-	}
 	return &Client{
 		backendType: contextType,
 		bs:          service,

example/backend.go

@@ -6,17 +6,31 @@ import (
 	"io"
 
 	"github.com/docker/api/backend"
+	"github.com/docker/api/compose"
 	"github.com/docker/api/containers"
 )
 
-type containerService struct{}
+type apiService struct {
+	containerService
+	composeService
+}
+
+func (a *apiService) ContainerService() containers.Service {
+	return &a.containerService
+}
+
+func (a *apiService) ComposeService() compose.Service {
+	return &a.composeService
+}
 
 func init() {
-	backend.Register("example", "example", func(ctx context.Context) (interface{}, error) {
-		return &containerService{}, nil
+	backend.Register("example", "example", func(ctx context.Context) (backend.Service, error) {
+		return &apiService{}, nil
 	})
 }
 
+type containerService struct{}
+
 func (cs *containerService) List(ctx context.Context) ([]containers.Container, error) {
 	return []containers.Container{
 		{
@@ -44,3 +58,23 @@ func (cs *containerService) Logs(ctx context.Context, containerName string, requ
 	fmt.Fprintf(request.Writer, "Following logs for container %q", containerName)
 	return nil
 }
+
+type composeService struct{}
+
+func (cs *composeService) Up(ctx context.Context, opts compose.ProjectOptions) error {
+	prj, err := compose.ProjectFromOptions(&opts)
+	if err != nil {
+		return err
+	}
+	fmt.Printf("Up command on project %q", prj.Name)
+	return nil
+}
+
+func (cs *composeService) Down(ctx context.Context, opts compose.ProjectOptions) error {
+	prj, err := compose.ProjectFromOptions(&opts)
+	if err != nil {
+		return err
+	}
+	fmt.Printf("Down command on project %q", prj.Name)
+	return nil
+}