incusd/instance/lxc: Pass log file to forknet dhcp

Signed-off-by: Gwendolyn <[email protected]>

Author: gwenya

internal/server/instance/drivers/driver_lxc.go

@@ -2499,7 +2499,23 @@ ff02::2 ip6-allrouters
 			return "", nil, err
 		}
 
-		err = lxcSetConfigItem(cc, "lxc.hook.start-host", fmt.Sprintf("/proc/%d/exe forknet dhcp %s", os.Getpid(), filepath.Join(d.Path(), "network")))
+		forknetDhcpLogfilePath := filepath.Join(d.LogPath(), "forknet-dhcp.log")
+		forknetDhcpLogfile, err := os.Create(forknetDhcpLogfilePath)
+		if err != nil {
+			return "", nil, err
+		}
+
+		err = forknetDhcpLogfile.Close()
+		if err != nil {
+			return "", nil, err
+		}
+
+		err = lxcSetConfigItem(cc, "lxc.hook.start-host", fmt.Sprintf(
+			"/proc/%d/exe forknet dhcp %s %s",
+			os.Getpid(),
+			filepath.Join(d.Path(), "network"),
+			forknetDhcpLogfilePath,
+		))
 		if err != nil {
 			return "", nil, err
 		}