appctl.erl

#!/usr/bin/env escript

config() ->
    [{app_node, app@localhost},
     {appctl_node, appctl@localhost},
     {cookie, app},
     {timeout, 100}].

main(Args) ->
    ScriptDir = filename:dirname(filename:absname(escript:script_name())),
    code:add_path(filename:join(ScriptDir, "ebin")),

    {AppCtlNode, Cookie} = get_values([appctl_node, cookie]),

    os:cmd("epmd -daemon"),
    net_kernel:start([AppCtlNode, shortnames]),
    erlang:set_cookie(node(), Cookie),

    try process(Args, ScriptDir)
    catch
	error:{cant_start, already_running} ->
	    error("Error: can't start because App is already running");
	error:{cant_stop, isnt_running} ->
	    error("Error: can't stop because App is not running");
	_:Reason ->
	    Message = io_lib:format("Unknown error occured.~n"
				    "Reason: ~p.~n"
				    "Stack trace: ~p",
				    [Reason, erlang:get_stacktrace()]),
	    error(Message)
    end.

process([Arg], ScriptDir) ->
    {AppNode, Cookie} = get_values([app_node, cookie]),
    if
	Arg =:= "--start"; Arg =:= "-s" ->
	    start(AppNode, Cookie, ScriptDir);
	Arg =:= "--stop"; Arg =:= "-q" ->
	    stop(AppNode);
	Arg =:= "--restart"; Arg =:= "-r" ->
	    stop(AppNode),
	    start(AppNode, Cookie, ScriptDir);
	true ->
	    usage()
    end;
process(_, _) ->
    usage().

start(AppNode, Cookie, ScriptDir) ->
    case net_adm:ping(AppNode) of
	pong -> erlang:error({cant_start, already_running});
	pang -> ok
    end,

    Deps = string:join(lists:foldl(fun(Dep, Acc) ->
					   ["-pa", filename:join(ScriptDir, Dep) | Acc]
				   end, [], ["ebin", "deps/*/ebin"]), " "),

    Cmd = io_lib:format("erl -detached -sname ~p -setcookie ~p "
			"+K true "
			"-boot start_sasl -config log "
			"~s "
			"-s app",
			[AppNode, Cookie, Deps]),
    os:cmd(Cmd).

stop(AppNode) ->
    case net_adm:ping(AppNode) of
	pong -> ok;
	pang -> erlang:error({cant_stop, isnt_running})
    end,

    rpc:call(AppNode, init, stop, []),
    wait_for_stop(AppNode, get_value(timeout)).

wait_for_stop(AppNode, Timeout) ->
    case net_adm:ping(AppNode) of
	pong ->
	    timer:sleep(Timeout),
	    wait_for_stop(AppNode, Timeout);
	pang ->
	    ok
    end.

usage() ->
    io:format("Usage: ~s [--start | -s] [--stop | -q] [--restart | -r]~n",
	      [escript:script_name()]).

get_value(Key) ->
    proplists:get_value(Key, config()).

get_values(Keys) ->
    get_values(Keys, config()).
get_values(Keys, Config) when is_tuple(Keys) ->
    get_values(tuple_to_list(Keys), Config);
get_values(Keys, Config) when is_list (Keys) ->
    Values = lists:foldl(fun(Key, Values) ->
				 [proplists:get_value(Key, Config) | Values]
			 end, [], Keys),
    list_to_tuple(lists:reverse(Values)).

error(Message) ->
    io:format(Message ++ ".~n"),
    halt(1).