Merge branch 'cloudamqp-max_connections' into stable

Author: michaelklishin

Makefile

@@ -25,6 +25,7 @@ define PROJECT_ENV
 	    %% breaks the QPid Java client
 	    {frame_max, 131072},
 	    {channel_max, 0},
+	    {connection_max, infinity},
 	    {heartbeat, 60},
 	    {msg_store_file_size_limit, 16777216},
 	    {fhc_write_buffering, true},

docs/rabbitmq.config.example

@@ -218,6 +218,25 @@
    %%
    %% {channel_max, 0},
 
+   %% Set the max permissible number of client connections to the node.
+   %% `infinity` means "no limit".
+   %%
+   %% This limit applies to client connections to all listeners (regardless of
+   %% the protocol, whether TLS is used and so on). CLI tools and inter-node
+   %% connections are exempt.
+   %%
+   %% When client connections are rapidly opened in succession, it is possible
+   %% for the total connection count to go slightly higher than the configured limit.
+   %% The limit works well as a general safety measure.
+   %%
+   %% Clients that are hitting the limit will see their TCP connections fail or time out.
+   %%
+   %% Introduced in 3.6.13.
+   %%
+   %% Related doc guide: http://www.rabbitmq.com/networking.html.
+   %%
+   %% {connection_max, infinity},
+
    %% TCP socket options.
    %%
    %% Related doc guide: http://www.rabbitmq.com/networking.html.

src/tcp_listener_sup.erl

@@ -49,10 +49,11 @@ start_link(IPAddress, Port, Transport, SocketOpts, ProtoSup, ProtoOpts, OnStartu
 init({IPAddress, Port, Transport, SocketOpts, ProtoSup, ProtoOpts, OnStartup, OnShutdown,
       ConcurrentAcceptorCount, Label}) ->
     {ok, AckTimeout} = application:get_env(rabbit, ssl_handshake_timeout),
+    MaxConnections = rabbit_misc:get_env(rabbit, connection_max, infinity),
     {ok, {{one_for_all, 10, 10}, [
         ranch:child_spec({acceptor, IPAddress, Port}, ConcurrentAcceptorCount,
             Transport, [{port, Port}, {ip, IPAddress},
-                {max_connections, infinity},
+                {max_connections, MaxConnections},
                 {ack_timeout, AckTimeout},
                 {connection_type, supervisor}|SocketOpts],
             ProtoSup, ProtoOpts),