albatross/app/vmm_log.ml

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2017-05-26 14:30:34 +00:00
(* (c) 2017 Hannes Mehnert, all rights reserved *)
(* the process responsible for event log *)
(* communication channel is a single unix domain socket shared between vmmd and
vmm_log. There are two commands from vmmd to vmm_log, history and data. *)
(* TODO: this should (optionally?) persist to a remote target *)
(* internally, a ring buffer for the last N events is preserved in memory
each new event is directly written to disk! *)
open Lwt.Infix
open Astring
open Vmm_wire
open Vmm_wire.Log
let my_version = `WV0
let write_complete s str =
let l = String.length str in
let b = Bytes.unsafe_of_string str in
let rec w off =
let len = l - off in
Lwt_unix.write s b off len >>= fun n ->
if n = len then Lwt.return_unit else w (off + n)
in
w 0
let pp_sockaddr ppf = function
| Lwt_unix.ADDR_UNIX str -> Fmt.pf ppf "unix domain socket %s" str
| Lwt_unix.ADDR_INET (addr, port) -> Fmt.pf ppf "TCP %s:%d"
(Unix.string_of_inet_addr addr) port
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let handle fd ring s addr () =
Logs.info (fun m -> m "handling connection from %a" pp_sockaddr addr) ;
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let str = Fmt.strf "%a: CONNECT\n" (Ptime.pp_human ~tz_offset_s:0 ()) (Ptime_clock.now ()) in
write_complete fd str >>= fun () ->
let rec loop () =
Vmm_lwt.read_exactly s >>= function
| Error (`Msg e) ->
Logs.err (fun m -> m "error while reading %s" e) ;
loop ()
| Error _ ->
Logs.err (fun m -> m "exception while reading") ;
Lwt.return_unit
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| Ok (hdr, data) ->
let out =
(if not (version_eq hdr.version my_version) then
Error (`Msg "unknown version")
else match int_to_op hdr.tag with
| Some Data ->
(match decode_ts data with
| Ok ts -> Vmm_ring.write ring (ts, data)
| Error _ ->
Logs.warn (fun m -> m "ignoring error while decoding timestamp %s" data)) ;
Ok (`Data data)
| Some History ->
begin match decode_str data with
| Error e -> Error e
| Ok (str, off) -> match decode_ts ~off data with
| Error e -> Error e
| Ok ts ->
let elements = Vmm_ring.read_history ring ts in
let res = List.fold_left (fun acc (_, x) ->
match Vmm_wire.Log.decode_log_hdr (Cstruct.of_string x) with
| Ok (hdr, _) ->
Logs.debug (fun m -> m "found an entry: %a" (Vmm_core.Log.pp_hdr []) hdr) ;
if String.equal str (Vmm_core.string_of_id hdr.Vmm_core.Log.context) then
x :: acc
else
acc
| _ -> acc)
[] elements
in
(* just need a wrapper in tag = Log.Data, id = reqid *)
let out =
List.fold_left (fun acc x ->
let length = String.length x in
let hdr = Vmm_wire.create_header { length ; id = hdr.id ; tag = op_to_int Data ; version = my_version } in
(Cstruct.to_string hdr ^ x) :: acc)
[] (List.rev res)
in
Ok (`Out out)
end
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| _ -> Error (`Msg "unknown command"))
in
match out with
| Error (`Msg msg) ->
begin
Logs.err (fun m -> m "error while processing: %s" msg) ;
Vmm_lwt.write_raw s (fail ~msg hdr.id my_version) >>= function
| Error _ -> Logs.err (fun m -> m "error0 while writing") ; Lwt.return_unit
| Ok () -> loop ()
end
| Ok (`Data data) ->
begin
write_complete fd data >>= fun () ->
Vmm_lwt.write_raw s (success hdr.id my_version) >>= function
| Error _ -> Logs.err (fun m -> m "error1 while writing") ; Lwt.return_unit
| Ok () -> loop ()
end
| Ok (`Out datas) ->
Lwt_list.fold_left_s (fun r x -> match r with
| Error e -> Lwt.return (Error e)
| Ok () -> Vmm_lwt.write_raw s x)
(Ok ()) datas >>= function
| Error _ -> Logs.err (fun m -> m "error2 while writing") ; Lwt.return_unit
| Ok () ->
Vmm_lwt.write_raw s (success hdr.id my_version) >>= function
| Error _ -> Logs.err (fun m -> m "error3 while writing") ; Lwt.return_unit
| Ok () -> loop ()
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in
loop () >>= fun () ->
Lwt.catch (fun () -> Lwt_unix.close s) (fun _ -> Lwt.return_unit)
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let jump _ file sock =
Sys.(set_signal sigpipe Signal_ignore) ;
Lwt_main.run
(Lwt_unix.openfile file Lwt_unix.[O_APPEND;O_CREAT;O_WRONLY] 0o600 >>= fun fd ->
(Lwt_unix.file_exists sock >>= function
| true -> Lwt_unix.unlink sock
| false -> Lwt.return_unit) >>= fun () ->
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let s = Lwt_unix.(socket PF_UNIX SOCK_STREAM 0) in
Lwt_unix.(bind s (ADDR_UNIX sock)) >>= fun () ->
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Lwt_unix.listen s 1 ;
let ring = Vmm_ring.create () in
let rec loop () =
Lwt_unix.accept s >>= fun (cs, addr) ->
Lwt.async (handle fd ring cs addr) ;
loop ()
in
loop ())
let setup_log style_renderer level =
Fmt_tty.setup_std_outputs ?style_renderer ();
Logs.set_level level;
Logs.set_reporter (Logs_fmt.reporter ~dst:Format.std_formatter ())
open Cmdliner
let setup_log =
Term.(const setup_log
$ Fmt_cli.style_renderer ()
$ Logs_cli.level ())
let socket =
let doc = "Socket to listen on" in
let sock = Fpath.(to_string (Vmm_core.tmpdir / "log" + "sock")) in
Arg.(value & opt string sock & info [ "s" ; "socket" ] ~doc)
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let file =
let doc = "File to write the log to" in
Arg.(value & opt string "/var/log/albatross" & info [ "logfile" ] ~doc)
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let cmd =
Term.(ret (const jump $ setup_log $ file $ socket)),
Term.info "vmm_log" ~version:"%%VERSION_NUM%%"
let () = match Term.eval cmd with `Ok () -> exit 0 | _ -> exit 1