Introduce a limit for how many virtual hosts can be created in a cluster

deps/rabbit/priv/schema/rabbit.schema

@@ -897,6 +897,19 @@ end}.
  end
 }.
 
+{mapping, "vhost_max", "rabbit.vhost_max",
+  [{datatype, [{atom, infinity}, integer]}, {validators, ["non_negative_integer"]}]}.
+
+{translation, "rabbit.vhost_max",
+ fun(Conf) ->
+  case cuttlefish:conf_get("vhost_max", Conf, undefined) of
+      undefined -> cuttlefish:unset();
+      infinity  -> infinity;
+      Val when is_integer(Val) -> Val;
+      _         -> cuttlefish:invalid("should be a non-negative integer")
+  end
+ end
+}.
 
 {mapping, "max_message_size", "rabbit.max_message_size",
     [{datatype, integer}, {validators, ["max_message_size"]}]}.

deps/rabbit/src/rabbit_queue_type.erl

@@ -55,6 +55,8 @@
 -type arguments() :: queue_arguments | consumer_arguments.
 -type queue_type() :: rabbit_classic_queue | rabbit_quorum_queue | rabbit_stream_queue.
 
+-export_type([queue_type/0]).
+
 -define(STATE, ?MODULE).
 
 %% Recoverable mirrors shouldn't really be a generic one, but let's keep it here until

deps/rabbit/src/rabbit_vhost.erl

@@ -162,6 +162,7 @@ add(Name, Metadata, ActingUser) ->
     end.
 
 do_add(Name, Metadata, ActingUser) ->
+    ok = is_over_vhost_limit(Name),
     Description = maps:get(description, Metadata, undefined),
     Tags = maps:get(tags, Metadata, []),
 
@@ -194,6 +195,7 @@ do_add(Name, Metadata, ActingUser) ->
                             [Name, Description, Tags])
     end,
     DefaultLimits = rabbit_db_vhost_defaults:list_limits(Name),
+
     {NewOrNot, VHost} = rabbit_db_vhost:create_or_get(Name, DefaultLimits, Metadata),
     case NewOrNot of
         new ->
@@ -284,9 +286,22 @@ delete(VHost, ActingUser) ->
     rabbit_vhost_sup_sup:delete_on_all_nodes(VHost),
     ok.
 
+-spec put_vhost(vhost:name(),
+    binary(),
+    vhost:tags(),
+    boolean(),
+    rabbit_types:username()) ->
+    'ok' | {'error', any()} | {'EXIT', any()}.
 put_vhost(Name, Description, Tags0, Trace, Username) ->
     put_vhost(Name, Description, Tags0, undefined, Trace, Username).
 
+-spec put_vhost(vhost:name(),
+    binary(),
+    vhost:unparsed_tags() | vhost:tags(),
+    rabbit_queue_type:queue_type() | 'undefined',
+    boolean(),
+    rabbit_types:username()) ->
+    'ok' | {'error', any()} | {'EXIT', any()}.
 put_vhost(Name, Description, Tags0, DefaultQueueType, Trace, Username) ->
     Tags = case Tags0 of
       undefined   -> <<"">>;
@@ -331,6 +346,26 @@ put_vhost(Name, Description, Tags0, DefaultQueueType, Trace, Username) ->
     end,
     Result.
 
+-spec is_over_vhost_limit(vhost:name()) -> 'ok' | no_return().
+is_over_vhost_limit(Name) ->
+    Limit = rabbit_misc:get_env(rabbit, vhost_max, infinity),
+    is_over_vhost_limit(Name, Limit).
+
+-spec is_over_vhost_limit(vhost:name(), 'infinity' | non_neg_integer())
+        -> 'ok' | no_return().
+is_over_vhost_limit(_Name, infinity) ->
+    ok;
+is_over_vhost_limit(Name, Limit) when is_integer(Limit) ->
+    case length(rabbit_db_vhost:list()) >= Limit of
+        false ->
+            ok;
+        true ->
+            ErrorMsg = rabbit_misc:format("cannot create vhost '~ts': "
+                                          "vhost limit of ~tp is reached",
+                                          [Name, Limit]),
+            exit({vhost_limit_exceeded, ErrorMsg})
+    end.
+
 %% when definitions are loaded on boot, Username here will be ?INTERNAL_USER,
 %% which does not actually exist
 maybe_grant_full_permissions(_Name, ?INTERNAL_USER) ->

deps/rabbit/src/vhost.erl

@@ -46,6 +46,8 @@
 
 -type(description() :: binary()).
 -type(tag() :: atom()).
+-type(tags() :: [tag()]).
+-type(unparsed_tags() :: binary() | string() | atom()).
 
 -type vhost() :: vhost_v2().
 
@@ -76,6 +78,8 @@
               metadata/0,
               description/0,
               tag/0,
+              unparsed_tags/0,
+              tags/0,
               vhost/0,
               vhost_v2/0,
               vhost_pattern/0,

deps/rabbit/test/per_node_limit_SUITE.erl

@@ -21,7 +21,8 @@ all() ->
 groups() ->
     [
      {parallel_tests, [parallel], [
-                                   node_connection_limit
+                                   node_connection_limit,
+                                   vhost_limit
                                   ]}
     ].
 
@@ -58,6 +59,9 @@ end_per_group(_Group, Config) ->
 init_per_testcase(Testcase, Config) ->
     rabbit_ct_helpers:testcase_started(Config, Testcase).
 
+end_per_testcase(vhost_limit = Testcase, Config) ->
+    [rabbit_ct_broker_helpers:delete_vhost(Config, integer_to_binary(I)) || I <- lists:seq(1,4)],
+    rabbit_ct_helpers:testcase_finished(Config, Testcase);
 end_per_testcase(Testcase, Config) ->
     rabbit_ct_helpers:testcase_finished(Config, Testcase).
 
@@ -78,7 +82,25 @@ node_connection_limit(Config) ->
 
     set_node_limit(Config, infinity),
     C = rabbit_ct_client_helpers:open_unmanaged_connection(Config, 0),
-    true = is_pid(C).
+    true = is_pid(C),
+    close_all_connections([C]),
+    ok.
+
+vhost_limit(Config) ->
+    set_vhost_limit(Config, 0),
+    {'EXIT',{vhost_limit_exceeded, _}} = rabbit_ct_broker_helpers:add_vhost(Config, <<"foo">>),
+
+    set_vhost_limit(Config, 5),
+    [ok = rabbit_ct_broker_helpers:add_vhost(Config, integer_to_binary(I)) || I <- lists:seq(1,4)],
+    {'EXIT',{vhost_limit_exceeded, _}} = rabbit_ct_broker_helpers:add_vhost(Config, <<"5">>),
+    [rabbit_ct_broker_helpers:delete_vhost(Config, integer_to_binary(I)) || I <- lists:seq(1,4)],
+
+    set_vhost_limit(Config, infinity),
+    [ok = rabbit_ct_broker_helpers:add_vhost(Config, integer_to_binary(I)) || I <- lists:seq(1,4)],
+    ok = rabbit_ct_broker_helpers:add_vhost(Config, <<"5">>),
+    [rabbit_ct_broker_helpers:delete_vhost(Config, integer_to_binary(I)) || I <- lists:seq(1,5)],
+    ok.
+
 
 %% -------------------------------------------------------------------
 %% Implementation
@@ -97,3 +119,8 @@ set_node_limit(Config, Limit) ->
     rabbit_ct_broker_helpers:rpc(Config, 0,
                                  application,
                                  set_env, [rabbit, connection_max, Limit]).
+
+set_vhost_limit(Config, Limit) ->
+    rabbit_ct_broker_helpers:rpc(Config, 0,
+                                 application,
+                                 set_env, [rabbit, vhost_max, Limit]).

deps/rabbitmq_cli/lib/rabbitmq/cli/ctl/commands/add_vhost_command.ex

@@ -51,6 +51,10 @@ defmodule RabbitMQ.CLI.Ctl.Commands.AddVhostCommand do
     {:error, ExitCodes.exit_usage(), "Unsupported default queue type"}
   end
 
+  def output({:badrpc, {:EXIT, {:vhost_limit_exceeded, msg}}}, _opts) do
+    {:error, ExitCodes.exit_usage(), msg}
+  end
+
   use RabbitMQ.CLI.DefaultOutput
 
   def usage,

deps/rabbitmq_management/src/rabbit_mgmt_wm_vhost.erl

@@ -10,14 +10,16 @@
 -export([init/2, resource_exists/2, to_json/2,
          content_types_provided/2, content_types_accepted/2,
          is_authorized/2, allowed_methods/2, accept_content/2,
-         delete_resource/2, id/1, put_vhost/6]).
+         delete_resource/2, id/1]).
 -export([variances/2]).
 
 -import(rabbit_misc, [pget/2]).
 
 -include_lib("rabbitmq_management_agent/include/rabbit_mgmt_records.hrl").
 -include_lib("rabbit_common/include/rabbit.hrl").
 
+-dialyzer({nowarn_function, accept_content/2}).
+
 %%--------------------------------------------------------------------
 
 init(Req, _State) ->
@@ -60,25 +62,28 @@ accept_content(ReqData0, Context = #context{user = #user{username = Username}})
     rabbit_mgmt_util:with_decode(
       [], ReqData0, Context,
       fun(_, BodyMap, ReqData) ->
-        Trace = rabbit_mgmt_util:parse_bool(maps:get(tracing, BodyMap, undefined)),
-        Description = maps:get(description, BodyMap, <<"">>),
-        Tags = maps:get(tags, BodyMap, <<"">>),
-        %% defaultqueuetype was an unfortunate name picked originally for 3.11.0,
-        %% so fall back to it. See rabbitmq/rabbitmq-server#7734.
-        FallbackQT = maps:get(defaultqueuetype, BodyMap, undefined),
-        DefaultQT = maps:get(default_queue_type, BodyMap, FallbackQT),
-        case put_vhost(Name, Description, Tags, DefaultQT, Trace, Username) of
-            ok ->
-                {true, ReqData, Context};
-            {error, timeout} = E ->
-                rabbit_mgmt_util:internal_server_error(
-                  "Timed out while waiting for the vhost to initialise", E,
-                  ReqData0, Context);
-            {error, E} ->
-                rabbit_mgmt_util:internal_server_error(
-                  "Error occured while adding vhost", E,
-                  ReqData0, Context)
-        end
+              Trace = rabbit_mgmt_util:parse_bool(maps:get(tracing, BodyMap, undefined)),
+              Description = maps:get(description, BodyMap, <<"">>),
+              Tags = maps:get(tags, BodyMap, <<"">>),
+              %% defaultqueuetype was an unfortunate name picked originally for 3.11.0,
+              %% so fall back to it. See rabbitmq/rabbitmq-server#7734.
+              FallbackQT = maps:get(defaultqueuetype, BodyMap, undefined),
+              DefaultQT = maps:get(default_queue_type, BodyMap, FallbackQT),
+              case rabbit_vhost:put_vhost(Name, Description, Tags, DefaultQT, Trace, Username) of
+                  ok ->
+                      {true, ReqData, Context};
+                  {error, timeout} = E ->
+                      rabbit_mgmt_util:internal_server_error(
+                        "Timed out while waiting for the vhost to initialise", E,
+                        ReqData0, Context);
+                  {error, E} ->
+                      rabbit_mgmt_util:internal_server_error(
+                        "Error occured while adding vhost", E,
+                        ReqData0, Context);
+                  {'EXIT', {vhost_limit_exceeded,
+                      Explanation}} ->
+                      rabbit_mgmt_util:bad_request(list_to_binary(Explanation), ReqData, Context)
+              end
       end).
 
 delete_resource(ReqData, Context = #context{user = #user{username = Username}}) ->
@@ -101,5 +106,3 @@ id(ReqData) ->
       Value   -> Value
     end.
 
-put_vhost(Name, Description, Tags, DefaultQT, Trace, Username) ->
-    rabbit_vhost:put_vhost(Name, Description, Tags, DefaultQT, Trace, Username).