incusd/instance/lxc: Cleanup DHCP client

Signed-off-by: Stéphane Graber <stgraber@stgraber.org>

cmd/incusd/main_forknet.go

@@ -384,6 +384,13 @@ func (c *cmdForknet) RunDHCP(cmd *cobra.Command, args []string) error {
 		return nil
 	}
 
+	// Create PID file.
+	err = os.WriteFile(filepath.Join(args[0], "dhcp.pid"), []byte(fmt.Sprintf("%d", os.Getpid())), 0644)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Giving up on DHCP, couldn't write PID file: %v\n", err)
+		return nil
+	}
+
 	// Handle DHCP renewal.
 	for {
 		// Wait until it's renewal time.

internal/server/instance/drivers/driver_lxc.go

@@ -3228,6 +3228,17 @@ func (d *lxc) onStop(args map[string]string) error {
 		// Clean up devices.
 		d.cleanupDevices(false, "")
 
+		// Stop DHCP client if any.
+		if util.PathExists(filepath.Join(d.Path(), "network", "dhcp.pid")) {
+			dhcpPIDStr, err := os.ReadFile(filepath.Join(d.Path(), "network", "dhcp.pid"))
+			if err == nil {
+				dhcpPID, err := strconv.Atoi(strings.TrimSpace(string(dhcpPIDStr)))
+				if err == nil {
+					_ = unix.Kill(dhcpPID, unix.SIGTERM)
+				}
+			}
+		}
+
 		// Remove directory ownership (to avoid issue if uidmap is re-used)
 		err := os.Chown(d.Path(), 0, 0)
 		if err != nil {