Add respawn command

main.go

@@ -6,6 +6,7 @@ import (
 	log "github.com/Sirupsen/logrus"
 	"github.com/docker/docker/pkg/reexec"
 	osInit "github.com/rancherio/os/init"
+	"github.com/rancherio/os/respawn"
 	"github.com/rancherio/os/sysinit"
 	"github.com/rancherio/os/user"
 )
@@ -17,6 +18,7 @@ func main() {
 	reexec.Register("/sbin/init-sys", sysinit.SysInit)
 	reexec.Register("/usr/bin/system-docker", user.SystemDocker)
 	reexec.Register("system-docker", user.SystemDocker)
+	reexec.Register("respawn", respawn.Main)
 
 	if !reexec.Init() {
 		log.Fatalf("Failed to find an entry point for %s", os.Args[0])

respawn/respawn.go

@@ -0,0 +1,65 @@
+package respawn
+
+import (
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"strings"
+	"sync"
+	"time"
+
+	log "github.com/Sirupsen/logrus"
+)
+
+func Main() {
+	input, err := ioutil.ReadAll(os.Stdin)
+	if err != nil {
+		panic(err)
+	}
+
+	var wait sync.WaitGroup
+
+	for _, line := range strings.Split(string(input), "\n") {
+		wait.Add(1)
+		go execute(line, wait)
+	}
+
+	wait.Wait()
+}
+
+func execute(line string, wait sync.WaitGroup) {
+	start := time.Now()
+	count := 0
+
+	for {
+		args := strings.Split(line, " ")
+
+		cmd := exec.Command(args[0], args[1:]...)
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+
+		err := cmd.Start()
+		if err != nil {
+			log.Error("%s : %v", line, err)
+		}
+
+		err = cmd.Wait()
+		if err != nil {
+			log.Error("%s : %v", line, err)
+		}
+
+		count++
+
+		if count > 10 {
+			if start.Sub(time.Now()) <= (1 * time.Second) {
+				log.Errorf("%s : restarted too fast, not executing", line)
+				break
+			}
+
+			count = 0
+			start = time.Now()
+		}
+	}
+
+	wait.Done()
+}