vmmd: teardown gracefully (kill all vms), install SIGTERM handler to teardown

app/vmmd.ml

@@ -71,7 +71,7 @@ let handle out fd addr =
       (Ok ()) wires >|= function
     | Ok () -> Ok ()
     | Error (`Msg msg) ->
-      Logs.err (fun m -> m "error in process %s: %s" txt msg) ;
+      Logs.err (fun m -> m "error in processing data %s: %s" txt msg) ;
       Error ()
   in
   let rec loop () =
@@ -128,12 +128,13 @@ let create_mbox sock =
        if <stat> fails, we'd need to retransmit all VM info to stat (or stat has to ask at connect) *)
     let rec loop () =
       Lwt_mvar.take mvar >>= fun data ->
+      Logs.debug (fun m -> m "writing %a" Vmm_commands.pp_wire data) ;
       Vmm_lwt.write_wire fd data >>= function
       | Ok () -> loop ()
       | Error `Exception -> invalid_arg ("exception while writing to " ^ Fmt.to_to_string pp_socket sock) ;
     in
     Lwt.async loop ;
-    Some (mvar, fd)
+    Some (mvar, fd, Lwt_mutex.create ())
 
 let server_socket sock =
   let name = socket_path sock in
@@ -152,53 +153,71 @@ let rec stats_loop () =
   stats_loop ()
 
 let jump _ =
-  Sys.(set_signal sigpipe Signal_ignore) ;
+  Sys.(set_signal sigpipe Signal_ignore);
   Lwt_main.run
     (server_socket `Vmmd >>= fun ss ->
-     (create_mbox `Console >|= function
-       | None -> invalid_arg "cannot connect to console socket"
-       | Some c -> c) >>= fun (c, c_fd) ->
-     create_mbox `Stats >>= fun s ->
      (create_mbox `Log >|= function
        | None -> invalid_arg "cannot connect to log socket"
-       | Some l -> l) >>= fun (l, l_fd) ->
-     let write_reply (header, cmd) mvar fd =
-       Lwt_mvar.put mvar (header, cmd) >>= fun () ->
-       Vmm_lwt.read_wire fd >|= function
+       | Some l -> l) >>= fun (l, l_fd, l_mut) ->
+     let self_destruct () =
+       Vmm_vmmd.kill !state ;
+       (* not too happy about the sleep here, but cleaning up resources is
+          really important (fifos, vm images, tap devices) - which is done in
+          asynchronous (waiter tasks)
+       *)
+       Lwt_unix.sleep 1. >>= fun () ->
+       Vmm_lwt.safe_close ss
+     in
+     Sys.(set_signal sigterm (Signal_handle (fun _ -> Lwt.async self_destruct)));
+     (create_mbox `Console >|= function
+       | None -> invalid_arg "cannot connect to console socket"
+       | Some c -> c) >>= fun (c, c_fd, c_mut) ->
+     create_mbox `Stats >>= fun s ->
+
+     let write_reply (header, cmd) name mvar fd mut =
+       Lwt_mutex.with_lock mut (fun () ->
+           Lwt_mvar.put mvar (header, cmd) >>= fun () ->
+           Vmm_lwt.read_wire fd) >|= function
        | Ok (header', reply) ->
          if not Vmm_commands.(version_eq header.version header'.version) then
-           Error (`Msg "wrong version in reply")
+           Error (`Msg ("wrong version in reply from " ^ name))
          else if not Vmm_commands.(Int64.equal header.sequence header'.sequence) then
-           Error (`Msg "wrong id in reply")
+           Error (`Msg (
+               Fmt.strf "wrong id %Lu (expected %Lu) in reply from %s"
+                 header'.Vmm_commands.sequence header.Vmm_commands.sequence name))
          else begin match reply with
            | `Success _ -> Ok ()
-           | `Failure msg -> Error (`Msg msg)
-           | _ -> Error (`Msg "unexpected data")
+           | `Failure msg -> Error (`Msg (msg ^ " from " ^ name))
+           | _ -> Error (`Msg ("unexpected data from " ^ name))
          end
-       | Error _ -> Error (`Msg "error in read")
+       | Error _ -> Error (`Msg ("error in read from " ^ name))
      in
      let out = function
        | `Stat wire ->
          begin match s with
            | None -> Lwt.return (Ok ())
-           | Some (s, s_fd) -> write_reply wire s s_fd
+           | Some (s, s_fd, s_mut) -> write_reply wire "stats" s s_fd s_mut
          end
-       | `Log wire -> write_reply wire l l_fd
-       | `Cons wire -> write_reply wire c c_fd
+       | `Log wire -> write_reply wire "log" l l_fd l_mut
+       | `Cons wire -> write_reply wire "console" c c_fd c_mut
      in
      Lwt.async stats_loop ;
-     let rec loop () =
-       Lwt_unix.accept ss >>= fun (fd, addr) ->
-       Lwt_unix.set_close_on_exec fd ;
-       Lwt.async (fun () -> handle out fd addr) ;
-       loop ()
-     in
-     loop ())
+     Lwt.catch (fun () ->
+         let rec loop () =
+           Lwt_unix.accept ss >>= fun (fd, addr) ->
+           Lwt_unix.set_close_on_exec fd ;
+           Lwt.async (fun () -> handle out fd addr) ;
+           loop ()
+         in
+         loop ())
+       (fun e ->
+          Logs.err (fun m -> m "exception %s, shutting down" (Printexc.to_string e));
+          self_destruct ()))
 
 open Cmdliner
 
 let cmd =
-  Term.(ret (const jump $ setup_log)),
+  Term.(const jump $ setup_log),
   Term.info "vmmd" ~version:"%%VERSION_NUM%%"
 
 let () = match Term.eval cmd with `Ok () -> exit 0 | _ -> exit 1

src/vmm_vmmd.ml

@@ -16,6 +16,10 @@ type 'a t = {
   tasks : 'a String.Map.t ;
 }
 
+let kill t =
+  List.iter Vmm_unix.destroy
+    (List.map snd (Vmm_trie.all t.resources.Vmm_resources.unikernels))
+
 let init wire_version =
   let t = {
     wire_version ;

src/vmm_vmmd.mli

@@ -28,3 +28,5 @@ val handle_command : 'a t -> Vmm_commands.wire ->
                                       | `End ]) ]
 
 val setup_stats : 'a t -> Name.t -> Unikernel.t -> 'a t * out
+
+val kill : 'a t -> unit