cmd/app: multiple template uppers

Having multiple environments is useful, and this was trivial to implement.

Signed-off-by: Ophestra <cat@gensokyo.uk>

cmd/app/main.go

@@ -7,6 +7,7 @@ package main
 import (
 	"context"
 	"errors"
+	"fmt"
 	"io"
 	"log"
 	"os"
@@ -35,7 +36,7 @@ func main() {
 		flagVerbose bool
 		flagBase    string
 
-		base, template, initial, upper, work *check.Absolute
+		base, template, initial *check.Absolute
 	)
 	c := command.New(os.Stderr, log.Printf, "app", func([]string) (err error) {
 		msg.SwapVerbose(flagVerbose)
@@ -50,9 +51,7 @@ func main() {
 		}
 
 		template = base.Append("template")
-		initial = template.Append("initial")
-		upper = template.Append("upper")
-		work = template.Append("work")
+		initial = base.Append("initial")
 		return
 	}).Flag(
 		&flagVerbose,
@@ -71,7 +70,21 @@ func main() {
 		)
 		c.NewCommand(
 			"enter", "Enter mutable state template",
-			func([]string) error {
+			func(args []string) error {
+				if len(args) != 1 {
+					dents, err := os.ReadDir(template.String())
+					if err != nil {
+						return err
+					}
+					for _, dent := range dents {
+						if !dent.IsDir() {
+							continue
+						}
+						fmt.Println(dent.Name())
+					}
+					return nil
+				}
+
 				config := hst.Config{
 					ID: "app.hakurei.mutable",
 					Container: &hst.ContainerConfig{
@@ -80,8 +93,8 @@ func main() {
 							{FilesystemConfig: &hst.FSOverlay{
 								Target: fhs.AbsRoot,
 								Lower:  []*check.Absolute{initial},
-								Upper:  upper,
-								Work:   work,
+								Upper:  template.Append(args[0], "upper"),
+								Work:   template.Append(args[0], "work"),
 							}},
 							{FilesystemConfig: &hst.FSEphemeral{
 								Target: fhs.AbsTmp,
@@ -131,7 +144,17 @@ func main() {
 		"run", "Start the named application",
 		func(args []string) error {
 			if len(args) != 1 {
-				return errors.New("run requires 1 argument")
+				dents, err := os.ReadDir(base.Append("app").String())
+				if err != nil {
+					return err
+				}
+				for _, dent := range dents {
+					if dent.IsDir() {
+						continue
+					}
+					fmt.Println(dent.Name())
+				}
+				return nil
 			}
 
 			var config *hst.Config