feat: Initial commit

README.md

@@ -0,0 +1,5 @@
+# miniroot
+
+> docker but simpler
+
+Usage: `miniroot -root "/opt/something" -workdir "/usr/src/app" -init "/usr/loacal/bin/npm start"`

go.mod

@@ -0,0 +1,3 @@
+module git.ddd.rip/ptrcnull/miniroot
+
+go 1.17

main.go

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+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+	"syscall"
+)
+
+var rootPath = flag.String("root", "", "path to root directory")
+var initCmd = flag.String("init", "/sbin/init", "init command")
+var workdir = flag.String("workdir", "/", "work directory")
+
+func main() {
+	flag.Parse()
+
+	if *rootPath == "" {
+		fmt.Println("root directory not set")
+		os.Exit(1)
+	}
+
+	initParts := strings.Split(*initCmd, " ")
+	cmd := exec.Command(initParts[0], initParts[1:]...)
+	cmd.Dir = *workdir
+	cmd.SysProcAttr = &syscall.SysProcAttr{
+		Chroot:       *rootPath,
+		Cloneflags:   syscall.CLONE_NEWUSER|syscall.CLONE_NEWPID,
+		UidMappings: []syscall.SysProcIDMap{
+			{ContainerID: 0, HostID: os.Getuid(), Size: 1},
+		},
+		GidMappings: []syscall.SysProcIDMap{
+			{ContainerID: 0, HostID: os.Getgid(), Size: 1},
+		},
+	}
+	cmd.Stdin = os.Stdin
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	err := cmd.Start()
+	if err != nil {
+		fmt.Printf("failed to start: %s\n", err)
+	}
+
+	err = cmd.Wait()
+	if err != nil {
+		fmt.Printf("process exited with error: %s\n", err)
+	}
+}