readme: ejemplo de cache

main.go

@@ -17,6 +17,8 @@ func main() {
 	config, err := readConfig()
 	must(err)
 
+	must(os.RemoveAll("rootfs/"))
+
 	must(os.MkdirAll("rootfs/etc/apk/keys", 0700))
 	must(os.WriteFile("rootfs/etc/apk/repositories", []byte(
 		`https://dl-cdn.alpinelinux.org/alpine/v3.17/main
@@ -66,6 +68,8 @@ https://dl-cdn.alpinelinux.org/alpine/v3.17/community`), 0600))
 			"--ro-bind", ".", "/src",
 			"--dev-bind", "/dev", "/dev",
 			"--bind", tmp, "/work",
+			"--unshare-user", "--uid", "1000", "--gid", "1000",
+			"--setenv", "HOME", "/home/repro",
 			"--chdir", "/work",
 		},
 		cachedParams...)
@@ -77,6 +81,10 @@ https://dl-cdn.alpinelinux.org/alpine/v3.17/community`), 0600))
 	// cmd.Stdout = os.Stdout
 	// cmd.Stderr = os.Stderr
 	must(cmd.Run(), "bwrap apk add")
+	cmd = exec.Command("bwrap", append(params,
+		"--uid", "0",
+		"adduser", "-u", "1000", "-D", "repro")...)
+	must(cmd.Run(), "bwrap adduser repro")
 
 	cmd = exec.Command("bwrap", append(params, strings.Split(config.Command, " ")...)...)
 	cmd.Stdout = os.Stdout

readme.md

@@ -17,7 +17,8 @@ file repro-run
 ```
 
 ```sh
-echo '{"Command": "/src/test"}' | go run .
+echo '{"Command": "/src/test", "Cache": ["/home/repro/.cache/go-build"]}
+' | go run .
 ```
 
 genera