Refactor and simplify cnab-run main.

Signed-off-by: Silvin Lubecki <silvin.lubecki@docker.com>

Author: silvin-lubecki

cmd/cnab-run/inspect.go

@@ -7,7 +7,7 @@ import (
 	"github.com/docker/app/internal/packager"
 )
 
-func inspect() error {
+func inspectAction(instanceName string) error {
 	app, err := packager.Extract("")
 	// todo: merge additional compose file
 	if err != nil {

cmd/cnab-run/install.go

@@ -22,7 +22,7 @@ const (
 	imageMapFilePath = "/cnab/app/image-map.json"
 )
 
-func install(instanceName string) error {
+func installAction(instanceName string) error {
 	cli, err := setupDockerContext()
 	if err != nil {
 		return errors.Wrap(err, "unable to restore docker context")

cmd/cnab-run/main.go

@@ -8,76 +8,41 @@ import (
 	"github.com/docker/app/internal"
 )
 
-type cnabAction string
-
-const (
-	cnabActionInstall   = cnabAction("install")
-	cnabActionUninstall = cnabAction("uninstall")
-	cnabActionUpgrade   = cnabAction("upgrade")
-	cnabActionStatus    = cnabAction(internal.Namespace + "status")
-	cnabActionInspect   = cnabAction(internal.Namespace + "inspect")
-)
-
-type cnabOperation struct {
-	action       cnabAction
-	installation string
-}
-
-func getCnabAction() (cnabAction, error) {
-	action, ok := os.LookupEnv("CNAB_ACTION")
-	if !ok {
-		return "", errors.New("no CNAB action specified")
+type cnabAction func(string) error
+
+var (
+	cnabActions = map[string]cnabAction{
+		"install":                      installAction,
+		"upgrade":                      installAction,
+		"uninstall":                    uninstallAction,
+		internal.Namespace + "status":  statusAction,
+		internal.Namespace + "inspect": inspectAction,
 	}
-	return cnabAction(action), nil
-}
+)
 
-func getCnabOperation() (cnabOperation, error) {
+func getCnabAction() (cnabAction, string, error) {
 	// CNAB_ACTION should always be set. but in future we want to have
 	// claim-less actions. So we don't fail if no installation is set
-	action, err := getCnabAction()
-	if err != nil {
-		return cnabOperation{}, err
+	actionName, ok := os.LookupEnv("CNAB_ACTION")
+	if !ok {
+		return nil, "", errors.New("no CNAB action specified")
+	}
+	action, ok := cnabActions[actionName]
+	if !ok {
+		return nil, "", fmt.Errorf("action %q not supported", actionName)
 	}
-	return cnabOperation{
-		action:       action,
-		installation: os.Getenv("CNAB_INSTALLATION_NAME"),
-	}, nil
+	return action, actionName, nil
 }
 
 func main() {
-	op, err := getCnabOperation()
+	action, actionName, err := getCnabAction()
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "Error while parsing cnab operation: %s", err)
 		os.Exit(1)
 	}
-	switch op.action {
-	case cnabActionInstall:
-		if err := install(op.installation); err != nil {
-			fmt.Fprintf(os.Stderr, "Install failed: %s", err)
-			os.Exit(1)
-		}
-	case cnabActionUpgrade:
-		if err := install(op.installation); err != nil {
-			fmt.Fprintf(os.Stderr, "Upgrade failed: %s", err)
-			os.Exit(1)
-		}
-	case cnabActionUninstall:
-		if err := uninstall(op.installation); err != nil {
-			fmt.Fprintf(os.Stderr, "Uninstall failed: %s", err)
-			os.Exit(1)
-		}
-	case cnabActionStatus:
-		if err := status(op.installation); err != nil {
-			fmt.Fprintf(os.Stderr, "Status failed: %s", err)
-			os.Exit(1)
-		}
-	case cnabActionInspect:
-		if err := inspect(); err != nil {
-			fmt.Fprintf(os.Stderr, "Inspect failed: %s", err)
-			os.Exit(1)
-		}
-	default:
-		fmt.Fprintf(os.Stderr, "Action %q is not supported", op.action)
+	instanceName := os.Getenv("CNAB_INSTALLATION_NAME")
+	if err := action(instanceName); err != nil {
+		fmt.Fprintf(os.Stderr, "Action %q failed: %s", actionName, err)
 		os.Exit(1)
 	}
 }

cmd/cnab-run/status.go

@@ -9,7 +9,7 @@ import (
 	"github.com/pkg/errors"
 )
 
-func status(instanceName string) error {
+func statusAction(instanceName string) error {
 	cli, err := setupDockerContext()
 	if err != nil {
 		return errors.Wrap(err, "unable to restore docker context")

cmd/cnab-run/uninstall.go

@@ -8,7 +8,7 @@ import (
 	"github.com/pkg/errors"
 )
 
-func uninstall(instanceName string) error {
+func uninstallAction(instanceName string) error {
 	cli, err := setupDockerContext()
 	if err != nil {
 		return errors.Wrap(err, "unable to restore docker context")