• Reference >
• MongoDB Package Components >
• mongos

mongos

Synopsis

mongos for “MongoDB Shard,” is a routing service for MongoDB shard configurations that processes queries from the application layer, and determines the location of this data in the sharded cluster, in order to complete these operations. From the perspective of the application, a mongos instance behaves identically to any other MongoDB instance.

Considerations

Never change the name of the mongos binary.

Options

mongos

Core Options

--help, -h

Returns information on the options and use of mongos.

--version

Returns the mongos release number.

--config <filename>, -f <filename>

Specifies a configuration file for runtime configuration options. The configuration file is the preferred method for runtime configuration of mongos. The options are equivalent to the command-line configuration options. See Configuration File Options for more information.

Ensure the configuration file uses ASCII encoding. The mongos instance does not support configuration files with non-ASCII encoding, including UTF-8.

--verbose, -v

Increases the amount of internal reporting returned on standard output or in log files. Increase the verbosity with the -v form by including the option multiple times, (e.g. -vvvvv.)

--quiet

Runs the mongos in a quiet mode that attempts to limit the amount of output.

This option suppresses:

• output from database commands
• replication activity
• connection accepted events
• connection closed events

--port <port>

Default: 27017

Specifies the TCP port on which the MongoDB instance listens for client connections.

--bind_ip <ip address>

Default: All interfaces.

Changed in version 2.6.0: The deb and rpm packages include a default configuration file (/etc/mongod.conf) that sets --bind_ip to 127.0.0.1.

The IP addresses and/or full Unix domain socket paths on which mongos should listen for client connections. You may attach mongos to any interface. To bind to multiple addresses, enter a list of comma-separated values.

Example

localhost,/tmp/mongod.sock

You can specify both IPv4 and IPv6 addresses, or hostnames that resolve to an IPv4 or IPv6 address.

Example

localhost, 2001:0DB8:e132:ba26:0d5c:2774:e7f9:d513

Note

If specifying an IPv6 address or a hostname that resolves to an IPv6 address to --bind_ip, you must start mongos with --ipv6 to enable IPv6 support. Specifying an IPv6 address to --bind_ip does not enable IPv6 support.

If specifying a link-local IPv6 address (fe80::/10), you must append the zone index to that address (i.e. fe80::<address>%<adapter-name>).

Example

localhost,fe80::a00:27ff:fee0:1fcf%enp0s3

Tip

To avoid downtime, give each config server a logical DNS name (unrelated to the server’s physical or virtual hostname). Without logical DNS names, moving or renaming a config server requires shutting down every mongod and mongos instance in the sharded cluster.

Warning

Before binding to a non-localhost (e.g. publicly accessible) IP address, ensure you have secured your cluster from unauthorized access. For a complete list of security recommendations, see Security Checklist. At minimum, consider enabling authentication and hardening network infrastructure.

To bind to all IPv4 addresses, enter 0.0.0.0.

To bind to all IPv4 and IPv6 addresses, enter 0.0.0.0,::.

--maxConns <number>

The maximum number of simultaneous connections that mongos will accept. This setting has no effect if it is higher than your operating system’s configured maximum connection tracking threshold.

Do not assign too low of a value to this option, or you will encounter errors during normal application operation.

This is particularly useful for a mongos if you have a client that creates multiple connections and allows them to timeout rather than closing them.

In this case, set maxIncomingConnections to a value slightly higher than the maximum number of connections that the client creates, or the maximum size of the connection pool.

This setting prevents the mongos from causing connection spikes on the individual shards. Spikes like these may disrupt the operation and memory allocation of the sharded cluster.

Note

Changed in version 2.6: MongoDB removed the upward limit on the maxIncomingConnections setting.

--syslog

Sends all logging output to the host’s syslog system rather than to standard output or to a log file. , as with --logpath.

The --syslog option is not supported on Windows.

--syslogFacility <string>

Default: user

Specifies the facility level used when logging messages to syslog. The value you specify must be supported by your operating system’s implementation of syslog. To use this option, you must enable the --syslog option..

--logpath <path>

Sends all diagnostic logging information to a log file instead of to standard output or to the host’s syslog system. MongoDB creates the log file at the path you specify.

By default, MongoDB will move any existing log file rather than overwrite it. To instead append to the log file, set the --logappend option.

--logappend

Appends new entries to the end of the existing log file when the mongos instance restarts. Without this option, mongod will back up the existing log and create a new file.

--timeStampFormat <string>

Default: iso8601-local

The time format for timestamps in log messages. Specify one of the following values:

Value	Description
ctime	Displays timestamps as Wed Dec 31 18:17:54.811.
iso8601-utc	Displays timestamps in Coordinated Universal Time (UTC) in the ISO-8601 format. For example, for New York at the start of the Epoch: 1970-01-01T00:00:00.000Z
iso8601-local	Displays timestamps in local time in the ISO-8601 format. For example, for New York at the start of the Epoch: 1969-12-31T19:00:00.000-0500

--pidfilepath <path>

Specifies a file location to hold the process ID of the mongos process where mongos will write its PID. This is useful for tracking the mongos process in combination with the the --fork option. Without a specified --pidfilepath option, the process creates no PID file.

--keyFile <file>

Specifies the path to a key file that stores the shared secret that MongoDB instances use to authenticate to each other in a sharded cluster or replica set. --keyFile implies --auth. See Internal Authentication for more information.

--setParameter <options>

Specifies one of the MongoDB parameters described in MongoDB Server Parameters. You can specify multiple setParameter fields.

--httpinterface

Deprecated since version 3.2: HTTP interface for MongoDB

Enables the HTTP interface. Enabling the interface can increase network exposure.

Leave the HTTP interface disabled for production deployments. If you do enable this interface, you should only allow trusted clients to access this port. See Firewalls.

Note

• While MongoDB Enterprise does support Kerberos authentication, Kerberos is not supported in HTTP status interface in any version of MongoDB.

New in version 2.6.

--nounixsocket

Disables listening on the UNIX domain socket. --nounixsocket applies only to Unix-based systems.

The mongos process always listens on the UNIX socket unless one of the following is true:

• --nounixsocket is set
• net.bindIp is not set
• net.bindIp does not specify 127.0.0.1

New in version 2.6: mongos installed from official .deb and .rpm packages have the bind_ip configuration set to 127.0.0.1 by default.

--unixSocketPrefix <path>

Default: /tmp

The path for the UNIX socket. --unixSocketPrefix applies only to Unix-based systems.

If this option has no value, the mongos process creates a socket with /tmp as a prefix. MongoDB creates and listens on a UNIX socket unless one of the following is true:

• net.unixDomainSocket.enabled is false
• --nounixsocket is set
• net.bindIp is not set
• net.bindIp does not specify 127.0.0.1

--filePermissions <path>

Default: 0700

Sets the permission for the UNIX domain socket file.

--filePermissions applies only to Unix-based systems.

--fork

Enables a daemon mode that runs the mongos process in the background. By default mongos does not run as a daemon: typically you will run mongos as a daemon, either by using --fork or by using a controlling process that handles the daemonization process (e.g. as with upstart and systemd).

The --fork option is not supported on Windows.

Sharded Cluster Options

--configdb <replicasetName>/<config1>,<config2>...

Changed in version 3.2.

Specifies the configuration servers for the sharded cluster.

Starting in MongoDB 3.2, config servers for sharded clusters can be deployed as a replica set. The replica set config servers must run the WiredTiger storage engine. MongoDB 3.2 deprecates the use of three mirrored mongod instances for config servers.

Specify the config server replica set name and the hostname and port of at least one of the members of the config server replica set.

copy

sharding:
  configDB: <configReplSetName>/cfg1.example.net:27017, cfg2.example.net:27017,...

The mongos instances for the sharded cluster must specify the same config server replica set name but can specify hostname and port of different members of the replica set.

If using the deprecated mirrored instances, specify the hostnames and ports of the three mongod instances. The mongos instances must specify the same config string.

--localThreshold

Default: 15

Specifies the ping time, in milliseconds, that mongos uses to determine which secondary replica set members to pass read operations from clients. The default value of 15 corresponds to the default value in all of the client drivers.

When mongos receives a request that permits reads to secondary members, the mongos will:

• Find the member of the set with the lowest ping time.

• Construct a list of replica set members that is within a ping time of 15 milliseconds of the nearest suitable member of the set.

  If you specify a value for the --localThreshold option, mongos will construct the list of replica members that are within the latency allowed by this value.

• Select a member to read from at random from this list.

The ping time used for a member compared by the --localThreshold setting is a moving average of recent ping times, calculated at most every 10 seconds. As a result, some queries may reach members above the threshold until the mongos recalculates the average.

See the Read Preference for Replica Sets section of the read preference documentation for more information.

--chunkSize <value>

Default: 64

Determines the size in megabytes of each chunk in the sharded cluster. A size of 64 megabytes is ideal in most deployments: larger chunk size can lead to uneven data distribution; smaller chunk size can lead to inefficient movement of chunks between nodes.

--chunkSize affects chunk size only when you initialize the cluster for the first time. If you later modify the option, the new value has no effect. See the Modify Chunk Size in a Sharded Cluster procedure if you need to change the chunk size on an existing sharded cluster.

--noAutoSplit

Disables mongos from automatically splitting chunks for sharded collections. If set on all mongos instances, this prevents MongoDB from creating new chunks as the data in a collection grows.

Because any mongos in a cluster can create a split, to totally disable splitting in a cluster you must set --noAutoSplit on all mongos.

Warning

With --noAutoSplit specified, the data in your sharded cluster may become imbalanced over time. Use the option with caution.

TLS/SSL Options

See

Configure mongod and mongos for TLS/SSL for full documentation of MongoDB’s support.

--sslOnNormalPorts

Deprecated since version 2.6: Use --sslMode requireSSL instead.

Enables TLS/SSL for mongos.

With --sslOnNormalPorts, a mongos requires TLS/SSL encryption for all connections on the default MongoDB port, or the port specified by --port. By default, --sslOnNormalPorts is disabled.

For more information about TLS/SSL and MongoDB, see Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients .

--sslMode <mode>

New in version 2.6.

Enables TLS/SSL or mixed TLS/SSL used for all network connections. The argument to the --sslMode option can be one of the following:

Value	Description
disabled	The server does not use TLS/SSL.
allowSSL	Connections between servers do not use TLS/SSL. For incoming connections, the server accepts both TLS/SSL and non-TLS/non-SSL.
preferSSL	Connections between servers use TLS/SSL. For incoming connections, the server accepts both TLS/SSL and non-TLS/non-SSL.
requireSSL	The server uses and accepts only TLS/SSL encrypted connections.

If using x.509 authentication, --sslCAFile or ssl.CAFile must be specified.

For more information about TLS/SSL and MongoDB, see Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients .

--sslPEMKeyFile <filename>

Specifies the .pem file that contains both the TLS/SSL certificate and key. Specify the file name of the .pem file using relative or absolute paths.

You must specify --sslPEMKeyFile when TLS/SSL is enabled.

For more information about TLS/SSL and MongoDB, see Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients .

--sslPEMKeyPassword <value>

Specifies the password to de-crypt the certificate-key file (i.e. --sslPEMKeyFile). Use the --sslPEMKeyPassword option only if the certificate-key file is encrypted. In all cases, the mongos will redact the password from all logging and reporting output.

Changed in version 2.6: If the private key in the PEM file is encrypted and you do not specify the --sslPEMKeyPassword option, the mongos will prompt for a passphrase. See TLS/SSL Certificate Passphrase.

For more information about TLS/SSL and MongoDB, see Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients .

--clusterAuthMode <option>

Default: keyFile

New in version 2.6.

The authentication mode used for cluster authentication. If you use internal x.509 authentication, specify so here. This option can have one of the following values:

Value	Description
keyFile	Use a keyfile for authentication. Accept only keyfiles.
sendKeyFile	For rolling upgrade purposes. Send a keyfile for authentication but can accept both keyfiles and x.509 certificates.
sendX509	For rolling upgrade purposes. Send the x.509 certificate for authentication but can accept both keyfiles and x.509 certificates.
x509	Recommended. Send the x.509 certificate for authentication and accept only x.509 certificates.

If using x.509 authentication, --sslCAFile or ssl.CAFile must be specified.

For more information about TLS/SSL and MongoDB, see Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients .

--sslClusterFile <filename>

New in version 2.6.

Specifies the .pem file that contains the x.509 certificate-key file for membership authentication for the cluster or replica set.

If --sslClusterFile does not specify the .pem file for internal cluster authentication, the cluster uses the .pem file specified in the --sslPEMKeyFile option.

If using x.509 authentication, --sslCAFile or ssl.CAFile must be specified.

For more information about TLS/SSL and MongoDB, see Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients .

--sslClusterPassword <value>

New in version 2.6.

Specifies the password to de-crypt the x.509 certificate-key file specified with --sslClusterFile. Use the --sslClusterPassword option only if the certificate-key file is encrypted. In all cases, the mongos will redact the password from all logging and reporting output.

If the x.509 key file is encrypted and you do not specify the --sslClusterPassword option, the mongos will prompt for a passphrase. See TLS/SSL Certificate Passphrase.

For more information about TLS/SSL and MongoDB, see Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients .

--sslCAFile <filename>

Specifies the .pem file that contains the root certificate chain from the Certificate Authority. Specify the file name of the .pem file using relative or absolute paths.

If using x.509 authentication, --sslCAFile or ssl.CAFile must be specified.

For more information about TLS/SSL and MongoDB, see Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients .

--sslCRLFile <filename>

Specifies the the .pem file that contains the Certificate Revocation List. Specify the file name of the .pem file using relative or absolute paths.

For more information about TLS/SSL and MongoDB, see Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients .

--sslAllowConnectionsWithoutCertificates

Disables the requirement for TLS/SSL certificate validation that --sslCAFile enables. With the --sslAllowConnectionsWithoutCertificates option, the mongos will accept connections when the client does not present a certificate when establishing the connection.

If the client presents a certificate and the mongos has --sslAllowConnectionsWithoutCertificates enabled, the mongos will validate the certificate using the root certificate chain specified by --sslCAFile and reject clients with invalid certificates.

Use the --sslAllowConnectionsWithoutCertificates option if you have a mixed deployment that includes clients that do not or cannot present certificates to the mongos.

For more information about TLS/SSL and MongoDB, see Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients .

--sslAllowInvalidCertificates

Bypasses the validation checks for TLS/SSL certificates on other servers in the cluster and allows the use of invalid certificates to connect.

Note

Starting in MongoDB 3.2.21, if you specify --sslAllowInvalidCertificates or ssl.allowInvalidCertificates: true when using x.509 authentication, an invalid certificate is only sufficient to establish a TLS/SSL connection but is insufficient for authentication.

When using the --sslAllowInvalidCertificates setting, MongoDB logs a warning regarding the use of the invalid certificate.

For more information about TLS/SSL and MongoDB, see Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients .

--sslAllowInvalidHostnames

New in version 3.0.

Disables the validation of the hostnames in TLS/SSL certificates, when connecting to other members of the replica set or sharded cluster for inter-process authentication. This allows mongos to connect to other members if the hostnames in their certificates do not match their configured hostname.

For more information about TLS/SSL and MongoDB, see Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients .

--sslDisabledProtocols <protocol(s)>

New in version 3.0.7.

Prevents a MongoDB server running with TLS/SSL from accepting incoming connections that use a specific protocol or protocols. --sslDisabledProtocols recognizes the following protocols: TLS1_0, TLS1_1, and TLS1_2. Specifying an unrecognized protocol will prevent the server from starting.

To specify multiple protocols, use a comma separated list of protocols.

Members of replica sets and sharded clusters must speak at least one protocol in common.

See also

Disallow Protocols

--sslFIPSMode

Directs the mongos to use the FIPS mode of the installed OpenSSL library. Your system must have a FIPS compliant OpenSSL library to use the --sslFIPSMode option.

Note

FIPS-compatible TLS/SSL is available only in MongoDB Enterprise. See Configure MongoDB for FIPS for more information.

Audit Options

--auditDestination

Enables auditing and specifies where mongos sends all audit events.

--auditDestination can have one of the following values:

Value	Description
syslog	Output the audit events to syslog in JSON format. Not available on Windows. Audit messages have a syslog severity level of info and a facility level of user. The syslog message limit can result in the truncation of audit messages. The auditing system will neither detect the truncation nor error upon its occurrence.
console	Output the audit events to stdout in JSON format.
file	Output the audit events to the file specified in --auditPath in the format specified in --auditFormat.

Note

Available only in MongoDB Enterprise.

--auditFormat

New in version 2.6.

Specifies the format of the output file for auditing if --auditDestination is file. The --auditFormat option can have one of the following values:

Value	Description
JSON	Output the audit events in JSON format to the file specified in --auditPath.
BSON	Output the audit events in BSON binary format to the file specified in --auditPath.

Printing audit events to a file in JSON format degrades server performance more than printing to a file in BSON format.

Note

Available only in MongoDB Enterprise.

--auditPath

New in version 2.6.

Specifies the output file for auditing if --auditDestination has value of file. The --auditPath option can take either a full path name or a relative path name.

Note

Available only in MongoDB Enterprise.

--auditFilter

New in version 2.6.

Specifies the filter to limit the types of operations the audit system records. The option takes a string representation of a query document of the form:

copy

{ <field1>: <expression1>, ... }

The <field> can be any field in the audit message, including fields returned in the param document. The <expression> is a query condition expression.

To specify an audit filter, enclose the filter document in single quotes to pass the document as a string.

To specify the audit filter in a configuration file, you must use the YAML format of the configuration file.

Note

Available only in MongoDB Enterprise.

Additional Options

--ipv6

Enables IPv6 support. mongos disables IPv6 support by default.

Setting --ipv6 does not direct the mongos to listen on any local IPv6 addresses or interfaces. To configure the mongos to listen on an IPv6 interface, you must configure --bind_ip with one or more IPv6 addresses or hostnames that resolve to IPv6 addresses.

--jsonp

Permits JSONP access via an HTTP interface. Enabling the interface can increase network exposure. The --jsonp option enables the HTTP interface, even if the HTTP interface option is disabled.

Deprecated since version 3.2: HTTP interface for MongoDB

--noscripting

Disables the scripting engine.

←   mongod mongo  →

© MongoDB, Inc 2008-present. MongoDB, Mongo, and the leaf logo are registered trademarks of MongoDB, Inc.