How to permanently increase RabbitMQ file descriptors limit

I'm trying to permanently increase the RabbitMQ file descriptors limit. I've already increased the system limit to 65535 and did the same for the RabbitMQ process by adding an entry to the /etc/security/limits.d/rabbitmq.conf file.

Output of ulimit -n is 65536.

Output of su - rabbitmq -s /bin/sh -c 'ulimit -n' is 65535.

Output of rabbitmqctl status | grep -A 4 limit is:

{vm_memory_limit,16900370432},
{disk_free_limit,16900370432},
{disk_free,1786935627776},
{file_descriptors,
  [{total_limit,924},{total_used,5},{sockets_limit,829},{sockets_used,1}]},
{processes,[{limit,1048576},{used,204}]},
{run_queue,0},
{uptime,3}]

If I run rabbitmqctl eval 'file_handle_cache:set_limit(65000).' then I get:

{vm_memory_limit,16900370432},
{disk_free_limit,16900370432},
{disk_free,1786935721984},
{file_descriptors,
  [{total_limit,65000},
    {total_used,5},
    {sockets_limit,58498},
    {sockets_used,1}]},
{processes,[{limit,1048576},{used,204}]},
{run_queue,0},
{uptime,91}]

Does anyone know how can I permanently increase the file_descriptors total_limit? It goes back to 924 each time I restart RabbitMQ. I don't want it to change though, so I was wondering if you guys can tell what I'm missing here :D

For the sake of completeness follows my full /etc/rabbitmq/rabbitmq.config file:

%% -*- mode: erlang -*-
%% ----------------------------------------------------------------------------
%% RabbitMQ Sample Configuration File.
%%
%% See http://www.rabbitmq.com/configure.html for details.
%% ----------------------------------------------------------------------------
[
 {rabbit,
  [%%
   %% Network Connectivity
   %% ====================
   %%

   %% By default, RabbitMQ will listen on all interfaces, using
   %% the standard (reserved) AMQP port.
   %%
   %% {tcp_listeners, [5672]},

   %% To listen on a specific interface, provide a tuple of {IpAddress, Port}.
   %% For example, to listen only on localhost for both IPv4 and IPv6:
   %%
   %% {tcp_listeners, [{"127.0.0.1", 5672},
   %%                  {"::1",       5672}]},

   %% SSL listeners are configured in the same fashion as TCP listeners,
   %% including the option to control the choice of interface.
   %%
   %% {ssl_listeners, [5671]},

   %% Maximum time for AMQP 0-8/0-9/0-9-1 handshake (after socket connection
   %% and SSL handshake), in milliseconds.
   %%
   %% {handshake_timeout, 10000},

   %% Log levels (currently just used for connection logging).
   %% One of 'debug', 'info', 'warning', 'error' or 'none', in decreasing
   %% order of verbosity. Defaults to 'info'.
   %%
   %% {log_levels, [{connection, info}, {channel, info}]},

   %% Set to 'true' to perform reverse DNS lookups when accepting a
   %% connection. Hostnames will then be shown instead of IP addresses
   %% in rabbitmqctl and the management plugin.
   %%
   %% {reverse_dns_lookups, true},

   %%
   %% Security / AAA
   %% ==============
   %%

   %% The default "guest" user is only permitted to access the server
   %% via a loopback interface (e.g. localhost).
   %% {loopback_users, [<<"guest">>]},
   %%
   %% Uncomment the following line if you want to allow access to the
   %% guest user from anywhere on the network.
   %% {loopback_users, []},

   %% Configuring SSL.
   %% See http://www.rabbitmq.com/ssl.html for full documentation.
   %%
   %% {ssl_options, [{cacertfile,           "/path/to/testca/cacert.pem"},
   %%                {certfile,             "/path/to/server/cert.pem"},
   %%                {keyfile,              "/path/to/server/key.pem"},
   %%                {verify,               verify_peer},
   %%                {fail_if_no_peer_cert, false}]},

   %% Choose the available SASL mechanism(s) to expose.
   %% The two default (built in) mechanisms are 'PLAIN' and
   %% 'AMQPLAIN'. Additional mechanisms can be added via
   %% plugins.
   %%
   %% See http://www.rabbitmq.com/authentication.html for more details.
   %%
   %% {auth_mechanisms, ['PLAIN', 'AMQPLAIN']},

   %% Select an authentication database to use. RabbitMQ comes bundled
   %% with a built-in auth-database, based on mnesia.
   %%
   %% {auth_backends, [rabbit_auth_backend_internal]},

   %% Configurations supporting the rabbitmq_auth_mechanism_ssl and
   %% rabbitmq_auth_backend_ldap plugins.
   %%
   %% NB: These options require that the relevant plugin is enabled.
   %% See http://www.rabbitmq.com/plugins.html for further details.

   %% The RabbitMQ-auth-mechanism-ssl plugin makes it possible to
   %% authenticate a user based on the client's SSL certificate.
   %%
   %% To use auth-mechanism-ssl, add to or replace the auth_mechanisms
   %% list with the entry 'EXTERNAL'.
   %%
   %% {auth_mechanisms, ['EXTERNAL']},

   %% The rabbitmq_auth_backend_ldap plugin allows the broker to
   %% perform authentication and authorisation by deferring to an
   %% external LDAP server.
   %%
   %% For more information about configuring the LDAP backend, see
   %% http://www.rabbitmq.com/ldap.html.
   %%
   %% Enable the LDAP auth backend by adding to or replacing the
   %% auth_backends entry:
   %%
   %% {auth_backends, [rabbit_auth_backend_ldap]},

   %% This pertains to both the rabbitmq_auth_mechanism_ssl plugin and
   %% STOMP ssl_cert_login configurations. See the rabbitmq_stomp
   %% configuration section later in this file and the README in
   %% https://github.com/rabbitmq/rabbitmq-auth-mechanism-ssl for further
   %% details.
   %%
   %% To use the SSL cert's CN instead of its DN as the username
   %%
   %% {ssl_cert_login_from, common_name},

   %% SSL handshake timeout, in milliseconds.
   %%
   %% {ssl_handshake_timeout, 5000},

   %%
   %% Default User / VHost
   %% ====================
   %%

   %% On first start RabbitMQ will create a vhost and a user. These
   %% config items control what gets created. See
   %% http://www.rabbitmq.com/access-control.html for further
   %% information about vhosts and access control.
   %%
   %% {default_vhost,       <<"/">>},
   %% {default_user,        <<"guest">>},
   %% {default_pass,        <<"guest">>},
   %% {default_permissions, [<<".*">>, <<".*">>, <<".*">>]},

   %% Tags for default user
   %%
   %% For more details about tags, see the documentation for the
   %% Management Plugin at http://www.rabbitmq.com/management.html.
   %%
   %% {default_user_tags, [administrator]},

   %%
   %% Additional network and protocol related configuration
   %% =====================================================
   %%

   %% Set the default AMQP heartbeat delay (in seconds).
   %%
   %% {heartbeat, 600},

   %% Set the max permissible size of an AMQP frame (in bytes).
   %%
   %% {frame_max, 131072},

   %% Set the max permissible number of channels per connection.
   %% 0 means "no limit".
   %%
   %% {channel_max, 128},

   %% Customising Socket Options.
   %%
   %% See (http://www.erlang.org/doc/man/inet.html#setopts-2) for
   %% further documentation.
   %%
   %% {tcp_listen_options, [binary,
   %%                       {packet,        raw},
   %%                       {reuseaddr,     true},
   %%                       {backlog,       128},
   %%                       {nodelay,       true},
   %%                       {exit_on_close, false}]},

   %%
   %% Resource Limits & Flow Control
   %% ==============================
   %%
   %% See http://www.rabbitmq.com/memory.html for full details.

   %% Memory-based Flow Control threshold.
   %%
      {vm_memory_high_watermark, 0.5},

   %% Fraction of the high watermark limit at which queues start to
   %% page message out to disc in order to free up memory.
   %%
   %% {vm_memory_high_watermark_paging_ratio, 0.5},

   %% Set disk free limit (in bytes). Once free disk space reaches this
   %% lower bound, a disk alarm will be set - see the documentation
   %% listed above for more details.
   %%
   %% {disk_free_limit, "4GB"},

   %% Alternatively, we can set a limit relative to total available RAM.
   %%
      {disk_free_limit, {mem_relative, 0.5}},

      {file_descriptors, [
        {total_limit, 65000}
      ]}

   %%
   %% Misc/Advanced Options
   %% =====================
   %%
   %% NB: Change these only if you understand what you are doing!
   %%

   %% To announce custom properties to clients on connection:
   %%
   %% {server_properties, []},

   %% How to respond to cluster partitions.
   %% See http://www.rabbitmq.com/partitions.html for further details.
   %%
   %% {cluster_partition_handling, ignore},

   %% Make clustering happen *automatically* at startup - only applied
   %% to nodes that have just been reset or started for the first time.
   %% See http://www.rabbitmq.com/clustering.html#auto-config for
   %% further details.
   %%
   %% {cluster_nodes, {['[email protected]'], disc}},

   %% Interval (in milliseconds) at which we send keepalive messages
   %% to other cluster members. Note that this is not the same thing
   %% as net_ticktime; missed keepalive messages will not cause nodes
   %% to be considered down.
   %%
   %% {cluster_keepalive_interval, 10000},

   %% Set (internal) statistics collection granularity.
   %%
   %% {collect_statistics, none},

   %% Statistics collection interval (in milliseconds).
   %%
   %% {collect_statistics_interval, 5000},

   %% Explicitly enable/disable hipe compilation.
   %%
   %% {hipe_compile, true},

   %% Timeout used when waiting for Mnesia tables in a cluster to
   %% become available.
   %%
   %% {mnesia_table_loading_timeout, 30000},

   %% Size in bytes below which to embed messages in the queue index. See
   %% http://www.rabbitmq.com/persistence-conf.html
   %%
   %% {queue_index_embed_msgs_below, 4096}

  ]},

 %% ----------------------------------------------------------------------------
 %% Advanced Erlang Networking/Clustering Options.
 %%
 %% See http://www.rabbitmq.com/clustering.html for details
 %% ----------------------------------------------------------------------------
 {kernel,
  [%% Sets the net_kernel tick time.
   %% Please see http://erlang.org/doc/man/kernel_app.html and
   %% http://www.rabbitmq.com/nettick.html for further details.
   %%
   %% {net_ticktime, 60}
  ]},

 %% ----------------------------------------------------------------------------
 %% RabbitMQ Management Plugin
 %%
 %% See http://www.rabbitmq.com/management.html for details
 %% ----------------------------------------------------------------------------

 {rabbitmq_management,
  [%% Pre-Load schema definitions from the following JSON file. See
   %% http://www.rabbitmq.com/management.html#load-definitions
   %%
   %% {load_definitions, "/path/to/schema.json"},

   %% Log all requests to the management HTTP API to a file.
   %%
   %% {http_log_dir, "/path/to/access.log"},

   %% Change the port on which the HTTP listener listens,
   %% specifying an interface for the web server to bind to.
   %% Also set the listener to use SSL and provide SSL options.
   %%
   %% {listener, [{port,     12345},
   %%             {ip,       "127.0.0.1"},
   %%             {ssl,      true},
   %%             {ssl_opts, [{cacertfile, "/path/to/cacert.pem"},
   %%                         {certfile,   "/path/to/cert.pem"},
   %%                         {keyfile,    "/path/to/key.pem"}]}]},

   %% One of 'basic', 'detailed' or 'none'. See
   %% http://www.rabbitmq.com/management.html#fine-stats for more details.
   %% {rates_mode, basic},

   %% Configure how long aggregated data (such as message rates and queue
   %% lengths) is retained. Please read the plugin's documentation in
   %% http://www.rabbitmq.com/management.html#configuration for more
   %% details.
   %%
   %% {sample_retention_policies,
   %%  [{global,   [{60, 5}, {3600, 60}, {86400, 1200}]},
   %%   {basic,    [{60, 5}, {3600, 60}]},
   %%   {detailed, [{10, 5}]}]}
  ]},

 %% ----------------------------------------------------------------------------
 %% RabbitMQ Shovel Plugin
 %%
 %% See http://www.rabbitmq.com/shovel.html for details
 %% ----------------------------------------------------------------------------

 {rabbitmq_shovel,
  [{shovels,
    [%% A named shovel worker.
     %% {my_first_shovel,
     %%  [

     %% List the source broker(s) from which to consume.
     %%
     %%   {sources,
     %%    [%% URI(s) and pre-declarations for all source broker(s).
     %%     {brokers, ["amqp://user:[email protected]/my_vhost"]},
     %%     {declarations, []}
     %%    ]},

     %% List the destination broker(s) to publish to.
     %%   {destinations,
     %%    [%% A singular version of the 'brokers' element.
     %%     {broker, "amqp://"},
     %%     {declarations, []}
     %%    ]},

     %% Name of the queue to shovel messages from.
     %%
     %% {queue, <<"your-queue-name-goes-here">>},

     %% Optional prefetch count.
     %%
     %% {prefetch_count, 10},

     %% when to acknowledge messages:
     %% - no_ack: never (auto)
     %% - on_publish: after each message is republished
     %% - on_confirm: when the destination broker confirms receipt
     %%
     %% {ack_mode, on_confirm},

     %% Overwrite fields of the outbound basic.publish.
     %%
     %% {publish_fields, [{exchange,    <<"my_exchange">>},
     %%                   {routing_key, <<"from_shovel">>}]},

     %% Static list of basic.properties to set on re-publication.
     %%
     %% {publish_properties, [{delivery_mode, 2}]},

     %% The number of seconds to wait before attempting to
     %% reconnect in the event of a connection failure.
     %%
     %% {reconnect_delay, 2.5}

     %% ]} %% End of my_first_shovel
    ]}
   %% Rather than specifying some values per-shovel, you can specify
   %% them for all shovels here.
   %%
   %% {defaults, [{prefetch_count,     0},
   %%             {ack_mode,           on_confirm},
   %%             {publish_fields,     []},
   %%             {publish_properties, [{delivery_mode, 2}]},
   %%             {reconnect_delay,    2.5}]}
  ]},

 %% ----------------------------------------------------------------------------
 %% RabbitMQ Stomp Adapter
 %%
 %% See http://www.rabbitmq.com/stomp.html for details
 %% ----------------------------------------------------------------------------

 {rabbitmq_stomp,
  [%% Network Configuration - the format is generally the same as for the broker

   %% Listen only on localhost (ipv4 & ipv6) on a specific port.
   %% {tcp_listeners, [{"127.0.0.1", 61613},
   %%                  {"::1",       61613}]},

   %% Listen for SSL connections on a specific port.
   %% {ssl_listeners, [61614]},

   %% Additional SSL options

   %% Extract a name from the client's certificate when using SSL.
   %%
   %% {ssl_cert_login, true},

   %% Set a default user name and password. This is used as the default login
   %% whenever a CONNECT frame omits the login and passcode headers.
   %%
   %% Please note that setting this will allow clients to connect without
   %% authenticating!
   %%
   %% {default_user, [{login,    "guest"},
   %%                 {passcode, "guest"}]},

   %% If a default user is configured, or you have configured use SSL client
   %% certificate based authentication, you can choose to allow clients to
   %% omit the CONNECT frame entirely. If set to true, the client is
   %% automatically connected as the default user or user supplied in the
   %% SSL certificate whenever the first frame sent on a session is not a
   %% CONNECT frame.
   %%
   %% {implicit_connect, true}
  ]},

 %% ----------------------------------------------------------------------------
 %% RabbitMQ MQTT Adapter
 %%
 %% See https://github.com/rabbitmq/rabbitmq-mqtt/blob/stable/README.md
 %% for details
 %% ----------------------------------------------------------------------------

 {rabbitmq_mqtt,
  [%% Set the default user name and password. Will be used as the default login
   %% if a connecting client provides no other login details.
   %%
   %% Please note that setting this will allow clients to connect without
   %% authenticating!
   %%
   %% {default_user, <<"guest">>},
   %% {default_pass, <<"guest">>},

   %% Enable anonymous access. If this is set to false, clients MUST provide
   %% login information in order to connect. See the default_user/default_pass
   %% configuration elements for managing logins without authentication.
   %%
   %% {allow_anonymous, true},

   %% If you have multiple chosts, specify the one to which the
   %% adapter connects.
   %%
   %% {vhost, <<"/">>},

   %% Specify the exchange to which messages from MQTT clients are published.
   %%
   %% {exchange, <<"amq.topic">>},

   %% Specify TTL (time to live) to control the lifetime of non-clean sessions.
   %%
   %% {subscription_ttl, 1800000},

   %% Set the prefetch count (governing the maximum number of unacknowledged
   %% messages that will be delivered).
   %%
   %% {prefetch, 10},

   %% TCP/SSL Configuration (as per the broker configuration).
   %%
   %% {tcp_listeners, [1883]},
   %% {ssl_listeners, []},

   %% TCP/Socket options (as per the broker configuration).
   %%
   %% {tcp_listen_options, [binary,
   %%                       {packet,    raw},
   %%                       {reuseaddr, true},
   %%                       {backlog,   128},
   %%                       {nodelay,   true}]}
  ]},

 %% ----------------------------------------------------------------------------
 %% RabbitMQ AMQP 1.0 Support
 %%
 %% See https://github.com/rabbitmq/rabbitmq-amqp1.0/blob/stable/README.md
 %% for details
 %% ----------------------------------------------------------------------------

 {rabbitmq_amqp1_0,
  [%% Connections that are not authenticated with SASL will connect as this
   %% account. See the README for more information.
   %%
   %% Please note that setting this will allow clients to connect without
   %% authenticating!
   %%
   %% {default_user, "guest"},

   %% Enable protocol strict mode. See the README for more information.
   %%
   %% {protocol_strict_mode, false}
  ]},

 %% ----------------------------------------------------------------------------
 %% RabbitMQ LDAP Plugin
 %%
 %% See http://www.rabbitmq.com/ldap.html for details.
 %%
 %% ----------------------------------------------------------------------------

 {rabbitmq_auth_backend_ldap,
  [%%
   %% Connecting to the LDAP server(s)
   %% ================================
   %%

   %% Specify servers to bind to. You *must* set this in order for the plugin
   %% to work properly.
   %%
   %% {servers, ["your-server-name-goes-here"]},

   %% Connect to the LDAP server using SSL
   %%
   %% {use_ssl, false},

   %% Specify the LDAP port to connect to
   %%
   %% {port, 389},

   %% LDAP connection timeout, in milliseconds or 'infinity'
   %%
   %% {timeout, infinity},

   %% Enable logging of LDAP queries.
   %% One of
   %%   - false (no logging is performed)
   %%   - true (verbose logging of the logic used by the plugin)
   %%   - network (as true, but additionally logs LDAP network traffic)
   %%
   %% Defaults to false.
   %%
   %% {log, false},

   %%
   %% Authentication
   %% ==============
   %%

   %% Pattern to convert the username given through AMQP to a DN before
   %% binding
   %%
   %% {user_dn_pattern, "cn=${username},ou=People,dc=example,dc=com"},

   %% Alternatively, you can convert a username to a Distinguished
   %% Name via an LDAP lookup after binding. See the documentation for
   %% full details.

   %% When converting a username to a dn via a lookup, set these to
   %% the name of the attribute that represents the user name, and the
   %% base DN for the lookup query.
   %%
   %% {dn_lookup_attribute,   "userPrincipalName"},
   %% {dn_lookup_base,        "DC=gopivotal,DC=com"},

   %% Controls how to bind for authorisation queries and also to
   %% retrieve the details of users logging in without presenting a
   %% password (e.g., SASL EXTERNAL).
   %% One of
   %%  - as_user (to bind as the authenticated user - requires a password)
   %%  - anon    (to bind anonymously)
   %%  - {UserDN, Password} (to bind with a specified user name and password)
   %%
   %% Defaults to 'as_user'.
   %%
   %% {other_bind, as_user},

   %%
   %% Authorisation
   %% =============
   %%

   %% The LDAP plugin can perform a variety of queries against your
   %% LDAP server to determine questions of authorisation. See
   %% http://www.rabbitmq.com/ldap.html#authorisation for more
   %% information.

   %% Set the query to use when determining vhost access
   %%
   %% {vhost_access_query, {in_group,
   %%                       "ou=${vhost}-users,ou=vhosts,dc=example,dc=com"}},

   %% Set the query to use when determining resource (e.g., queue) access
   %%
   %% {resource_access_query, {constant, true}},

   %% Set queries to determine which tags a user has
   %%
   %% {tag_queries, []}
  ]}
].

depending on the OS, for Ubuntu and Debian you can do it as:

https://www.rabbitmq.com/install-rpm.html#linux-max-open-files-limit-options-other-linux

With systemd (Recent Linux Distributions)

On distributions that use systemd, the OS limits are controlled via a configuration file at /etc/systemd/system/rabbitmq-server.service.d/limits.conf, for example:

[Service]
LimitNOFILE=300000

If your Linux distribution is using systemd, it looks like systemd ignores /etc/security/limits.conf on purpose.

The linked bug report suggests to set LimitNOFILE in the unit file, but because in the case of RabbitMQ, this file is automatically generated, it's probably a bad idea.

The RabbitMQ website points to the Riack documentation for file descriptors limit tuning, maybe it can help you.

Note that a real unit file should be provided with RabbitMQ 3.6.2 so it integrates natively with systemd.