1 files changed, 174 insertions, 0 deletions
diff --git a/deps/rabbit/apps/rabbitmq_prelaunch/src/rabbit_boot_state_systemd.erl b/deps/rabbit/apps/rabbitmq_prelaunch/src/rabbit_boot_state_systemd.erl
new file mode 100644
index 0000000000..f838535b6a
--- /dev/null
+++ b/deps/rabbit/apps/rabbitmq_prelaunch/src/rabbit_boot_state_systemd.erl
@@ -0,0 +1,174 @@
+%% This Source Code Form is subject to the terms of the Mozilla Public
+%% License, v. 2.0. If a copy of the MPL was not distributed with this
+%% file, You can obtain one at https://mozilla.org/MPL/2.0/.
+%%
+%% Copyright (c) 2015-2020 VMware, Inc. or its affiliates.  All rights reserved.
+%%
+
+-module(rabbit_boot_state_systemd).
+
+-behaviour(gen_server).
+
+-export([start_link/0]).
+
+-export([init/1,
+         handle_call/3,
+         handle_cast/2,
+         terminate/2,
+         code_change/3]).
+
+-record(state, {mechanism,
+                sd_notify_module,
+                socket}).
+
+-define(LOG_PREFIX, "Boot state/systemd: ").
+
+start_link() ->
+    gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
+
+init([]) ->
+    case os:type() of
+        {unix, _} ->
+            case code:load_file(sd_notify) of
+                {module, sd_notify} ->
+                    {ok, #state{mechanism = legacy,
+                                sd_notify_module = sd_notify}};
+                {error, _} ->
+                    case os:getenv("NOTIFY_SOCKET") of
+                        false ->
+                            ignore;
+                        "" ->
+                            ignore;
+                        Socket ->
+                            {ok, #state{mechanism = socat,
+                                        socket = Socket}}
+                    end
+            end;
+        _ ->
+            ignore
+    end.
+
+handle_call(_Request, _From, State) ->
+    {noreply, State}.
+
+handle_cast({notify_boot_state, BootState}, State) ->
+    notify_boot_state(BootState, State),
+    {noreply, State}.
+
+terminate(normal, _State) ->
+    ok.
+
+code_change(_OldVsn, State, _Extra) ->
+    {ok, State}.
+
+%%% Private
+
+notify_boot_state(ready = BootState,
+                  #state{mechanism = legacy, sd_notify_module = SDNotify}) ->
+    rabbit_log_prelaunch:debug(
+      ?LOG_PREFIX "notifying of state `~s` (via native module)",
+      [BootState]),
+    sd_notify_legacy(SDNotify);
+notify_boot_state(ready = BootState,
+                  #state{mechanism = socat, socket = Socket}) ->
+    rabbit_log_prelaunch:debug(
+      ?LOG_PREFIX "notifying of state `~s` (via socat(1))",
+      [BootState]),
+    sd_notify_socat(Socket);
+notify_boot_state(BootState, _) ->
+    rabbit_log_prelaunch:debug(
+      ?LOG_PREFIX "ignoring state `~s`",
+      [BootState]),
+    ok.
+
+sd_notify_message() ->
+    "READY=1\nSTATUS=Initialized\nMAINPID=" ++ os:getpid() ++ "\n".
+
+sd_notify_legacy(SDNotify) ->
+    SDNotify:sd_notify(0, sd_notify_message()).
+
+%% socat(1) is the most portable way the sd_notify could be
+%% implemented in erlang, without introducing some NIF. Currently the
+%% following issues prevent us from implementing it in a more
+%% reasonable way:
+%% - systemd-notify(1) is unstable for non-root users
+%% - erlang doesn't support unix domain sockets.
+%%
+%% Some details on how we ended with such a solution:
+%%   https://github.com/rabbitmq/rabbitmq-server/issues/664
+sd_notify_socat(Socket) ->
+    case sd_current_unit() of
+        {ok, Unit} ->
+            rabbit_log_prelaunch:debug(
+              ?LOG_PREFIX "systemd unit for activation check: \"~s\"~n",
+              [Unit]),
+            sd_notify_socat(Socket, Unit);
+        _ ->
+            ok
+    end.
+
+sd_notify_socat(Socket, Unit) ->
+    try sd_open_port(Socket) of
+        Port ->
+            Port ! {self(), {command, sd_notify_message()}},
+            Result = sd_wait_activation(Port, Unit),
+            port_close(Port),
+            Result
+    catch
+        Class:Reason ->
+            rabbit_log_prelaunch:debug(
+              ?LOG_PREFIX "Failed to start socat(1): ~p:~p~n",
+              [Class, Reason]),
+            false
+    end.
+
+sd_current_unit() ->
+    CmdOut = os:cmd("ps -o unit= -p " ++ os:getpid()),
+    Ret = (catch re:run(CmdOut,
+                        "([-.@0-9a-zA-Z]+)",
+                        [unicode, {capture, all_but_first, list}])),
+    case Ret of
+        {'EXIT', _}     -> error;
+        {match, [Unit]} -> {ok, Unit};
+        _               -> error
+    end.
+
+socat_socket_arg("@" ++ AbstractUnixSocket) ->
+    "abstract-sendto:" ++ AbstractUnixSocket;
+socat_socket_arg(UnixSocket) ->
+    "unix-sendto:" ++ UnixSocket.
+
+sd_open_port(Socket) ->
+    open_port(
+        {spawn_executable, os:find_executable("socat")},
+        [{args, [socat_socket_arg(Socket), "STDIO"]},
+            use_stdio, out]).
+
+sd_wait_activation(Port, Unit) ->
+    case os:find_executable("systemctl") of
+        false ->
+            rabbit_log_prelaunch:debug(
+              ?LOG_PREFIX "systemctl(1) unavailable, falling back to sleep~n"),
+            timer:sleep(5000),
+            ok;
+        _ ->
+            sd_wait_activation(Port, Unit, 10)
+    end.
+
+sd_wait_activation(_, _, 0) ->
+    rabbit_log_prelaunch:debug(
+      ?LOG_PREFIX "service still in 'activating' state, bailing out~n"),
+    ok;
+sd_wait_activation(Port, Unit, AttemptsLeft) ->
+    Ret = os:cmd("systemctl show --property=ActiveState -- '" ++ Unit ++ "'"),
+    case Ret of
+        "ActiveState=activating\n" ->
+            timer:sleep(1000),
+            sd_wait_activation(Port, Unit, AttemptsLeft - 1);
+        "ActiveState=" ++ _ ->
+            ok;
+        _ = Err ->
+            rabbit_log_prelaunch:debug(
+              ?LOG_PREFIX "unexpected status from systemd: ~p~n", [Err]),
+            ok
+    end.