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RabbitMQ Configuration

Overview

RabbitMQ comes with default built-in settings. Those can be entirely sufficient in some environment (e.g. development and QA). If it runs fine, then you possibly don't need any configuration at all. For all other cases, as well as production deployment tuning, there is a way to configure many things in the broker as well as plugins.

This guide covers a number of topics related to configuration:

  • The ways in which various settings of the server and plugins are configured
  • Configuration file(s)
  • Environment variables
  • Most commonly configured core server settings
  • Troubleshooting: how to verify config file location and effective configuration
Since configuration affects many areas of the system, including plugins, individual documentation guides dive deeper into what can be configured.

Means of Configuration

RabbitMQ provides three general ways to customise the server:

Mechanism Description
Environment Variables define node name, file and directory locations, runtime flags (taken from the shell, or set in the environment configuration file, rabbitmq-env.conf/rabbitmq-env-conf.bat)
Configuration File defines server and plugin settings for and so on.
Runtime Parameters and Policies defines cluster-wide settings which can change at run time as well as settings that are convenient to configure for groups of queues (exchanges, etc) such as including optional queue arguments.

Most settings are configured using the first two methods. This guide, therefore, focuses on them.

Config File Locations

Default config file locations vary between operating systems and package types. This topic is covered in more details in the rest of this guide.

When in doubt about RabbitMQ config file location for your OS and installation method, consult the log file and/or management UI as explained in the following sections.

Verify Configuration: How to Find Config File Location

The active configuration file can be verified by inspecting RabbitMQ log file. It will show up in the log file at the top together with other broker boot log entries, for example:

node           : rabbit@example
home dir       : /var/lib/rabbitmq
config file(s) : /etc/rabbitmq/rabbitmq.config
In case log file cannot be found or read by RabbitMQ, log entry will say so:
node           : rabbit@example
home dir       : /var/lib/rabbitmq
config file(s) : /var/lib/rabbitmq/hare.config (not found)

Alternatively config file location can be found in the management UI, together with other details about nodes.

When troubleshooting configuration settings, it is very useful to veirfy that the config file path is correct, exists and can be loaded (e.g. the file is readable) before checking effective node configuration.

Verify Configuration: How to Check Effective Configuration

It is possible to print effective configuration (user provided values merged into defaults) using the rabbitmqctl environment command.

Checking effective configuration

Customise RabbitMQ Environment

Certain server parameters can be configured using environment variables: node name, RabbitMQ configuration file location, inter-node communication ports, Erlang VM flags, and so on.

Unix (general)

On Unix-based systems (including Linux, MacOSX) you can create/edit rabbitmq-env.conf to define environment variables. Its location is configurable using the RABBITMQ_CONF_ENV_FILE environment variable.

Use the standard environment variable names (but drop the RABBITMQ_ prefix) e.g.

#example rabbitmq-env.conf file entries
#Rename the node
NODENAME=bunny@myhost
#Config file location and new filename bunnies.config
CONFIG_FILE=/etc/rabbitmq/testdir/bunnies
More info on using rabbitmq-env.conf

Windows

If you need to customise names, ports, locations, it is easiest to configure environment variables in the Windows dialogue: Start > Settings > Control Panel > System > Advanced > Environment Variables. Then create or edit the system variable name and value.

Alternatively, you can create/edit rabbitmq-env-conf.bat to define environment variables. Its location is configurable using the RABBITMQ_CONF_ENV_FILE environment variable.

For environment changes to take effect on Windows, the service must be re-installed. It is not sufficient to restart the service. This can be done using the installer or on the command line with administrator permissions:

  • Start an admin command prompt
  • cd into the sbin folder under RabbitMQ server installation directory (e.g. C:\Program Files (x86)\RabbitMQ Server\rabbitmq_server-3.6.11\sbin)
  • Run rabbitmq-service.bat remove
  • Set environment variables via command line, i.e. run commands like the following: set RABBITMQ_BASE=c:\Data\RabbitMQ
  • Run rabbitmq-service.bat install
Alternative, if new configuration needs to take effect after next broker restart, one step can be skipped:
  • Start an admin command prompt
  • cd into the sbin folder under RabbitMQ server installation directory
  • Set environment variables via command line
  • Run rabbitmq-service.bat install, which will only update service parameters

RabbitMQ Environment Variables

RabbitMQ environment variable names have the prefix RABBITMQ_. A typical variable called RABBITMQ_var_name is set as follows:

  • a shell environment variable called RABBITMQ_var_name is used if this is defined;
  • otherwise, a variable called var_name is used if this is set in the rabbitmq-env.conf file;
  • otherwise, a system-specified default value is used.

In this way, variables set in the shell environment take priority over variables set in rabbitmq-env.conf, which in turn over-ride RabbitMQ built-in defaults.

It is unlikely you will need to set any of these environment variables. If you have non-standard requirements, then RabbitMQ environment variables include, but are not limited to:

NameDefaultDescription
RABBITMQ_NODE_IP_ADDRESS the empty string - meaning bind to all network interfaces. Change this if you only want to bind to one network interface. To bind to two or more interfaces, use the tcp_listeners key in rabbitmq.config.
RABBITMQ_NODE_PORT 5672
RABBITMQ_DIST_PORT RABBITMQ_NODE_PORT + 20000 Port used for inter-node and CLI tool communition. Ignored if your config file sets kernel.inet_dist_listen_min or kernel.inet_dist_listen_max keys. See Networking for details.
RABBITMQ_NODENAME
  • Unix*: rabbit@$HOSTNAME
  • Windows: rabbit@%COMPUTERNAME%
The node name should be unique per erlang-node-and-machine combination. To run multiple nodes, see the clustering guide.
RABBITMQ_CONF_ENV_FILE
  • Generic UNIX - $RABBITMQ_HOME/etc/rabbitmq/rabbitmq-env.conf
  • Debian - /etc/rabbitmq/rabbitmq-env.conf
  • RPM - /etc/rabbitmq/rabbitmq-env.conf
  • Mac OS X (Homebrew) - ${install_prefix}/etc/rabbitmq/rabbitmq-env.conf, the Homebrew prefix is usually /usr/local
  • Windows - %APPDATA%\RabbitMQ\rabbitmq-env-conf.bat
Location of the file that contains environment variable definitions (without the RABBITMQ_ prefix). Note that the file name on Windows is different from other operating systems.
RABBITMQ_USE_LONGNAME When set to true this will cause RabbitMQ to use fully qualified names to identify nodes. This may prove useful on EC2. Note that it is not possible to switch between using short and long names without resetting the node.
RABBITMQ_SERVICENAME Windows Service: RabbitMQ The name of the installed service. This will appear in services.msc.
RABBITMQ_CONSOLE_LOG Windows Service: Set this variable to new or reuse to redirect console output from the server to a file named %RABBITMQ_SERVICENAME%.debug in the default RABBITMQ_BASE directory.
  • If not set, console output from the server will be discarded (default).
  • new A new file will be created each time the service starts.
  • reuse The file will be overwritten each time the service starts.
RABBITMQ_CTL_ERL_ARGS None Parameters for the erl command used when invoking rabbitmqctl. This should be overridden for debugging purposes only.
RABBITMQ_SERVER_ERL_ARGS
  • Unix*: +P 1048576 +t 5000000 +stbt db +zdbbl 32000
  • Windows: None
Standard parameters for the erl command used when invoking the RabbitMQ Server. This should be overridden for debugging purposes only. Overriding this variable replaces the default value.
RABBITMQ_SERVER_ADDITIONAL_ERL_ARGS
  • Unix*: None
  • Windows: None
Additional parameters for the erl command used when invoking the RabbitMQ Server. The value of this variable is appended the default list of arguments (RABBITMQ_SERVER_ERL_ARGS). This is the environment variable to use if +K true needs to be overwritten.
RABBITMQ_SERVER_START_ARGS None Extra parameters for the erl command used when invoking the RabbitMQ Server. This will not override RABBITMQ_SERVER_ERL_ARGS.
* Unix, Linux, MacOSX

In addition, there are several environment variables which tell RabbitMQ where to locate its database, log files, plugins, configuration etc.

Other variables upon which RabbitMQ depends are:

NameDefaultDescription
HOSTNAME
  • Unix, Linux: env hostname
  • MacOSX: env hostname -s
The name of the current machine
COMPUTERNAME Windows: localhost The name of the current machine
ERLANG_SERVICE_MANAGER_PATH Windows Service: %ERLANG_HOME%\erts-x.x.x\bin This path is the location of erlsrv.exe, the Erlang service wrapper script.

Configuration File

The rabbitmq.config File

The configuration file rabbitmq.config allows the RabbitMQ core application, Erlang services and RabbitMQ plugins to be configured. It is a standard Erlang configuration file, documented on the Erlang Config Man Page.

An minimalistic example configuration file follows:

  [
    {rabbit, [{tcp_listeners, [5673]}]}
  ].

This example will alter the port RabbitMQ listens on for AMQP 0-9-1 client connections from 5672 to 5673.

To override main RabbitMQ config file location, use the RABBITMQ_CONFIG_FILE environment variable.

Note that this configuration file is not the same as the environment configuration file, rabbitmq-env.conf, which can be used to set environment variables on non-Windows systems.

Location of rabbitmq.config and rabbitmq-env.conf

The location of these files is distribution-specific. By default, they are not created, but expect to be located in the following places on each platform:

  • Generic UNIX - $RABBITMQ_HOME/etc/rabbitmq/
  • Debian - /etc/rabbitmq/
  • RPM - /etc/rabbitmq/
  • Mac OS X (Homebrew) - ${install_prefix}/etc/rabbitmq/, the Homebrew prefix is usually /usr/local
  • Windows - %APPDATA%\RabbitMQ\

If rabbitmq-env.conf doesn't exist, it can be created manually in the location, specified by the RABBITMQ_CONF_ENV_FILE variable. On Windows systems, it is named rabbitmq-env.bat.

If rabbitmq.config doesn't exist, it can be created manually. Set the RABBITMQ_CONFIG_FILE environment variable if you change the location. The Erlang runtime automatically appends the .config extension to the value of this variable.

Restart the server after changes. Windows service users will need to re-install the service after adding or removing a configuration file.

Example rabbitmq.config File

RabbitMQ server source repository contains an example configuration file named rabbitmq.config.example. This example file contains an example of most of the configuration items you might want to set (with some very obscure ones omitted) along with documentation for those settings. All configuration items are commented out in the example, so you can uncomment what you need. Note that the example file is meant to be used as, well, example, and should not be treated as a general recommendation.

In most distributions we place this example file in the same location as the real file should be placed (see above). However, for the Debian and RPM distributions policy forbids doing so; instead you can find it in /usr/share/doc/rabbitmq-server/ or /usr/share/doc/rabbitmq-server-3.6.11/ respectively.

Variables Configurable in rabbitmq.config

Many users of RabbitMQ never need to change any of these values, and some are fairly obscure. However, for completeness they are all listed here.

Key Documentation
tcp_listeners Ports or hostname/pair on which to listen for AMQP connections (without TLS). See the Networking guide for more details and examples.

Default: [5672]

num_tcp_acceptors Number of Erlang processes that will accept connections for the TCP listeners.

Default: 10

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

Default: 10000

ssl_listeners As above, for SSL connections.

Default: []

num_ssl_acceptors Number of Erlang processes that will accept connections for the SSL listeners.

Default: 1

ssl_options SSL configuration. See the SSL documentation.

Default: []

ssl_handshake_timeout SSL handshake timeout, in milliseconds.

Default: 5000

vm_memory_high_watermark Memory threshold at which the flow control is triggered. See the memory-based flow control documentation.

Default: 0.4

vm_memory_calculation_strategy Strategy for memory usage reporting. Can be one of the following:
  • rss - use operating system RSS memory reporting
  • erlang - use Erlang memory reporting

Default: rss

vm_memory_high_watermark_paging_ratio Fraction of the high watermark limit at which queues start to page messages out to disc to free up memory. See the memory-based flow control documentation.

Default: 0.5

disk_free_limit Disk free space limit of the partition on which RabbitMQ is storing data. When available disk space falls below this limit, flow control is triggered. The value may be set relative to the total amount of RAM (e.g. {mem_relative, 1.0}). The value may also be set to an integer number of bytes. Or, alternatively, in information units (e.g "50MB"). By default free disk space must exceed 50MB. See the Disk Alarms documentation.

Default: 50000000

log_levels Controls the granularity of logging. The value is a list of log event category and log level pairs.

The level can be one of 'none' (no events are logged), 'error' (only errors are logged), 'warning' (only errors and warning are logged), 'info' (errors, warnings and informational messages are logged), or 'debug' (errors, warnings, informational messages and debugging messages are logged).

At present there are four categories defined. Other, currently uncategorised, events are always logged.

The categories are:

  • channel - for all events relating to AMQP channels
  • connection - for all events relating to network connections
  • federation - for all events relating to federation
  • mirroring - for all events relating to mirrored queues

Default: [{connection, info}]

frame_max Maximum permissible size of a frame (in bytes) to negotiate with clients. Setting to 0 means "unlimited" but will trigger a bug in some QPid clients. Setting a larger value may improve throughput; setting a smaller value may improve latency.

Default: 131072

channel_max Maximum permissible number of channels to negotiate with clients. Setting to 0 means "unlimited". Using more channels increases memory footprint of the broker.

Default: 0

channel_operation_timeout Channel operation timeout in milliseconds (used internally, not directly exposed to clients due to messaging protocol differences and limitations).

Default: 15000

heartbeat Value representing the heartbeat delay, in seconds, that the server sends in the connection.tune frame. If set to 0, heartbeats are disabled. Clients might not follow the server suggestion, see the AMQP reference for more details. Disabling heartbeats might improve performance in situations with a great number of connections, but might lead to connections dropping in the presence of network devices that close inactive connections.

Default: 60 (580 prior to release 3.5.5)

default_vhost Virtual host to create when RabbitMQ creates a new database from scratch. The exchange amq.rabbitmq.log will exist in this virtual host.

Default: <<"/">>

default_user User name to create when RabbitMQ creates a new database from scratch.

Default: <<"guest">>

default_pass Password for the default user.

Default: <<"guest">>

default_user_tags Tags for the default user.

Default: [administrator]

default_permissions Permissions to assign to the default user when creating it.

Default: [<<".*">>, <<".*">>, <<".*">>]

loopback_users List of users which are only permitted to connect to the broker via a loopback interface (i.e. localhost).

If you wish to allow the default guest user to connect remotely, you need to change this to [].

Default: [<<"guest">>]

cluster_nodes Set this to cause clustering to happen automatically when a node starts for the very first time. The first element of the tuple is the nodes that the node will try to cluster to. The second element is either disc or ram and determines the node type.

Default: {[], disc}

server_properties List of key-value pairs to announce to clients on connection.

Default: []

collect_statistics Statistics collection mode. Primarily relevant for the management plugin. Options are:
  • none (do not emit statistics events)
  • coarse (emit per-queue / per-channel / per-connection statistics)
  • fine (also emit per-message statistics)
You probably don't want to change this yourself.

Default: none

collect_statistics_interval Statistics collection interval in milliseconds. Primarily relevant for the management plugin.

Default: 5000

management_db_cache_multiplier Affects the amount of time the management plugin will cache expensive management queries such as queue listings. The cache will multiply the elapsed time of the last query by this value and cache the result for this amount of time.

Default: 5

auth_mechanisms SASL authentication mechanisms to offer to clients.

Default: ['PLAIN', 'AMQPLAIN']

auth_backends

List of authentication and authorisation backends to use.

Other databases than rabbit_auth_backend_internal are available through plugins.

Default: [rabbit_auth_backend_internal]

reverse_dns_lookups Set to true to have RabbitMQ perform a reverse DNS lookup on client connections, and present that information through rabbitmqctl and the management plugin.

Default: false

delegate_count Number of delegate processes to use for intra-cluster communication. On a machine which has a very large number of cores and is also part of a cluster, you may wish to increase this value.

Default: 16

trace_vhosts Used internally by the tracer. You shouldn't change this.

Default: []

tcp_listen_options Default socket options. You probably don't want to change this.

Default:

[{backlog,       128},
 {nodelay,       true},
 {linger,        {true,0}},
 {exit_on_close, false}]
                

hipe_compile Set to true to precompile parts of RabbitMQ with HiPE, a just-in-time compiler for Erlang. This will increase server throughput at the cost of increased startup time.

You might see 20-50% better performance at the cost of a few minutes delay at startup. These figures are highly workload- and hardware-dependent.

HiPE support may not be compiled into your Erlang installation. If it is not, enabling this option will just cause a warning message to be displayed and startup will proceed as normal. For example, Debian / Ubuntu users will need to install the erlang-base-hipe package.

HiPE is not available at all on some platforms, notably including Windows.

HiPE has known issues in Erlang/OTP versions prior to 17.5. Using a recent Erlang/OTP version is highly recommended for HiPE.

Default: false

cluster_partition_handling How to handle network partitions. Available modes are:
  • ignore
  • pause_minority
  • {pause_if_all_down, [nodes], ignore | autoheal} where [nodes] is a list of node names
    (ex: ['rabbit@node1', 'rabbit@node2'])
  • autoheal
See the documentation on partitions for more information.

Default: ignore

cluster_keepalive_interval How frequently nodes should send keepalive messages to other nodes (in milliseconds). Note that this is not the same thing as net_ticktime; missed keepalive messages will not cause nodes to be considered down.

Default: 10000

queue_index_embed_msgs_below Size in bytes of message below which messages will be embedded directly in the queue index. You are advised to read the persister tuning documentation before changing this.

Default: 4096

msg_store_index_module Implementation module for queue indexing. You are advised to read the persister tuning documentation before changing this.

Default: rabbit_msg_store_ets_index

backing_queue_module Implementation module for queue contents. You probably don't want to change this.

Default: rabbit_variable_queue

msg_store_file_size_limit Tunable value for the persister. You almost certainly should not change this.

Default: 16777216

mnesia_table_loading_retry_limit Number of times to retry while waiting for Mnesia tables in a cluster to become available.

Default: 10

mnesia_table_loading_retry_timeout Time to wait per retry for Mnesia tables in a cluster to become available.

Default: 30000

queue_index_max_ journal_entries Tunable value for the persister. You almost certainly should not change this.

Default: 65536

queue_master_locator Queue master location strategy. Available strategies are:
  • <<"min-masters">>
  • <<"client-local">>
  • <<"random">>
See the documentation on queue master location for more information.

Default: <<"client-local">>

lazy_queue_explicit_ gc_run_operation_threshold Tunable value only for lazy queues when under memory pressure. This is the threshold at which the garbage collector and other memory reduction activities are triggered. A low value could reduce performance, and a high one can improve performance, but cause higher memory consumption. You almost certainly should not change this.

Default: 1000

queue_explicit_ gc_run_operation_threshold Tunable value only for normal queues when under memory pressure. This is the threshold at which the garbage collector and other memory reduction activities are triggered. A low value could reduce performance, and a high one can improve performance, but cause higher memory consumption. You almost certainly should not change this.

Default: 1000

In addition, many plugins can have sections in the configuration file, with names of the form rabbitmq_plugin. Our maintained plugins are documented in the following locations:

Configuration entry encryption

Sensitive configuration entries (e.g. password, URL containing credentials) can be encrypted in the RabbitMQ configuration file. The broker decrypts encrypted entries on start.

Note that encrypted configuration entries don't make the system meaningfully more secure. Nevertheless, they allow deployments of RabbitMQ to conform to regulations in various countries requiring that no sensitive data should appear in plain text in configuration files.

Encrypted values must be inside an Erlang encrypted tuple: {encrypted, ...}. Here is an example of a configuration file with an encrypted password for the default user:

[
  {rabbit, [
      {default_user, <<"guest">>},
      {default_pass,
        {encrypted,
         <<"cPAymwqmMnbPXXRVqVzpxJdrS8mHEKuo2V+3vt1u/fymexD9oztQ2G/oJ4PAaSb2c5N/hRJ2aqP/X0VAfx8xOQ==">>
        }
      },
      {config_entry_decoder, [
             {passphrase, <<"mypassphrase">>}
         ]}
    ]}
].
            
Note the config_entry_decoder key with the passphrase that RabbitMQ will use to decrypt encrypted values.

The passphrase doesn't have to be hardcoded in the configuration file, it can be in a separate file:

[
  {rabbit, [
      ...
      {config_entry_decoder, [
             {passphrase, {file, "/path/to/passphrase/file"}}
         ]}
    ]}
].
            
RabbitMQ can also request an operator to enter the passphrase when it starts by using {passphrase, prompt}.

Use rabbitmqctl and the encode command to encrypt values:

rabbitmqctl encode '<<"guest">>' mypassphrase
{encrypted,<<"... long encrypted value...">>}
rabbitmqctl encode '"amqp://fred:secret@host1.domain/my_vhost"' mypassphrase
{encrypted,<<"... long encrypted value...">>}
            
Add the decode command if you want to decrypt values:
rabbitmqctl decode '{encrypted, <<"...">>}' mypassphrase
<<"guest">>
rabbitmqctl decode '{encrypted, <<"...">>}' mypassphrase
"amqp://fred:secret@host1.domain/my_vhost"
            

Values of different types can be encoded. The example above encodes both binaries (<<"guest">>) and strings ("amqp://fred:secret@host1.domain/my_vhost").

The encryption mechanism uses PBKDF2 to produce a derived key from the passphrase. The default hash function is SHA512 and the default number of iterations is 1000. The default cipher is AES 256 CBC.

You can change these defaults in the configuration file:

[
  {rabbit, [
      ...
      {config_entry_decoder, [
             {passphrase, "mypassphrase"},
             {cipher, blowfish_cfb64},
             {hash, sha256},
             {iterations, 10000}
         ]}
    ]}
].          
On the command line:
rabbitmqctl encode --cipher blowfish_cfb64 --hash sha256 --iterations 10000 \
                     '<<"guest">>' mypassphrase