Add "dev render" command

pkg/appdefinition/appdefinition.go

@@ -120,6 +120,15 @@ func (a *AppDefinition) WithBuildParams(params map[string]interface{}) (*AppDefi
 	}, nil
 }
 
+func (a *AppDefinition) JSON() (string, error) {
+	app, err := a.ctx.Value()
+	if err != nil {
+		return "", err
+	}
+	data, err := json.MarshalIndent(app, "", "  ")
+	return string(data), err
+}
+
 func (a *AppDefinition) AppSpec() (*v1.AppSpec, error) {
 	app, err := a.ctx.Value()
 	if err != nil {

pkg/cli/dev.go

@@ -12,13 +12,15 @@ import (
 )
 
 func NewDev() *cobra.Command {
-	return cli.Command(&Dev{}, cobra.Command{
+	cmd := cli.Command(&Dev{}, cobra.Command{
 		Use:          "dev [flags] DIRECTORY",
 		SilenceUsage: true,
 		Short:        "Build and run an app in development mode",
 		Long:         "Build and run an app in development mode",
 		Args:         cobra.MaximumNArgs(1),
 	})
+	cmd.AddCommand(NewRender())
+	return cmd
 }
 
 type Dev struct {

pkg/cli/dev_render.go

@@ -0,0 +1,79 @@
+package cli
+
+import (
+	"fmt"
+
+	"github.com/acorn-io/acorn/pkg/appdefinition"
+	"github.com/acorn-io/acorn/pkg/build"
+	"github.com/acorn-io/acorn/pkg/cue"
+	"github.com/acorn-io/acorn/pkg/flagparams"
+	cli "github.com/rancher/wrangler-cli"
+	"github.com/spf13/cobra"
+	"github.com/spf13/pflag"
+)
+
+func NewRender() *cobra.Command {
+	cmd := cli.Command(&Render{}, cobra.Command{
+		Use:          "render [flags] DIRECTORY",
+		SilenceUsage: true,
+		Short:        "Evaluate and display an acorn.cue with deploy params",
+		Args:         cobra.MinimumNArgs(1),
+	})
+	cmd.Flags().SetInterspersed(false)
+	return cmd
+}
+
+type Render struct {
+	File string `short:"f" usage:"Name of the dev file" default:"DIRECTORY/acorn.cue"`
+}
+
+func (s *Render) Run(cmd *cobra.Command, args []string) error {
+	cwd := "."
+	if len(args) > 0 {
+		cwd = args[0]
+	}
+
+	buildFile := build.ResolveFile(s.File, cwd)
+	data, err := cue.ReadCUE(buildFile)
+	if err != nil {
+		return err
+	}
+
+	appDef, err := appdefinition.NewAppDefinition(data)
+	if err != nil {
+		return err
+	}
+
+	appSpec, err := appDef.AppSpec()
+	if err != nil {
+		return err
+	}
+
+	params, err := appDef.DeployParams()
+	if err != nil {
+		return err
+	}
+
+	flags := flagparams.New(s.File, params)
+	flags.Usage = usage(appSpec)
+
+	deployParams, err := flags.Parse(args)
+	if pflag.ErrHelp == err {
+		return nil
+	} else if err != nil {
+		return err
+	}
+
+	appDef, err = appDef.WithDeployParams(deployParams)
+	if err != nil {
+		return err
+	}
+
+	v, err := appDef.JSON()
+	if err != nil {
+		return err
+	}
+	fmt.Print(v)
+
+	return nil
+}