Fix dhcpcd zoombie issue

cmd/cloudinitsave/cloudinitsave.go

@@ -65,6 +65,9 @@ func Main() {
 	if err := saveCloudConfig(); err != nil {
 		log.Errorf("Failed to save cloud-config: %v", err)
 	}
+
+	// exit dhcpcd
+	netconf.StopDhcpcd()
 }
 
 func saveCloudConfig() error {

cmd/network/network.go

@@ -2,6 +2,9 @@ package network
 
 import (
 	"io/ioutil"
+	"os"
+	"os/signal"
+	"syscall"
 
 	"github.com/rancher/os/config"
 	"github.com/rancher/os/pkg/docker"
@@ -29,7 +32,11 @@ func Main() {
 		log.Error(err)
 	}
 
-	select {}
+	signalChan := make(chan os.Signal, 1)
+	signal.Notify(signalChan, syscall.SIGTERM)
+	<-signalChan
+	log.Info("Received SIGTERM, shutting down")
+	netconf.StopDhcpcd()
 }
 
 func ApplyNetworkConfig(cfg *config.CloudConfig) {

pkg/netconf/netconf_linux.go

@@ -25,6 +25,7 @@ const (
 
 var (
 	defaultDhcpArgs = []string{"dhcpcd", "-MA4"}
+	exitDhcpArgs    = []string{"dhcpcd", "-x"}
 	dhcpReleaseCmd  = "dhcpcd --release"
 )
 
@@ -527,5 +528,13 @@ func GetValidLinkList() ([]netlink.Link, error) {
 	}
 
 	return validLinkList, nil
-
+}
+
+func StopDhcpcd() {
+	cmd := exec.Command(exitDhcpArgs[0], exitDhcpArgs[1:]...)
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	if err := cmd.Run(); err != nil {
+		log.Errorf("Failed to run command [%v]: %v", cmd, err)
+	}
 }