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replSetInitiate![](/docs/v5.2/assets/link.svg)
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replSetInitiate
The
replSetInitiate
command initializes a new replica set.To run
replSetInitiate
, use thedb.runCommand( { <command> } )
method.Note
Run the command on only one of the
mongod
instances for the replica set.Use the following syntax:
{ replSetInitiate : <config_document> } The
<config_document>
is a document that specifies the replica set's configuration. For instance, here's a config document for creating a simple 3-member replica set:{ _id : <setname>, members : [ {_id : 0, host : <host0>}, {_id : 1, host : <host1>}, {_id : 2, host : <host2>}, ] } Important
To avoid configuration updates due to IP address changes, use DNS hostnames instead of IP addresses. It is particularly important to use a DNS hostname instead of an IP address when configuring replica set members or sharded cluster members.
Use hostnames instead of IP addresses to configure clusters across a split network horizon. Starting in MongDB 5.0, nodes that are only configured with an IP address will fail startup validation and will not start.
IP Binding![](/docs/v5.2/assets/link.svg)
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.
MongoDB binaries, mongod
and mongos
, bind
to localhost by default. If the net.ipv6
configuration file
setting or the --ipv6
command line option is set for the binary,
the binary additionally binds to the localhost IPv6 address.
By default mongod
and mongos
that are
bound to localhost only accept connections from clients that are
running on the same computer. This binding behavior includes
mongosh
and other members of your replica set or sharded
cluster. Remote clients cannot connect to binaries that are bound only
to localhost.
To override the default binding and bind to other IP addresses, use the
net.bindIp
configuration file setting or the --bind_ip
command-line option to specify a list of hostnames or IP addresses.
Warning
Starting in MongDB 5.0, split horizon DNS nodes that are
only configured with an IP address fail startup validation and
report an error. See disableSplitHorizonIPCheck
.
For example, the following mongod
instance binds to both
the localhost and the hostname My-Example-Associated-Hostname
, which is
associated with the IP address 198.51.100.1
:
mongod --bind_ip localhost,My-Example-Associated-Hostname
In order to connect to this instance, remote clients must specify
the hostname or its associated IP address 198.51.100.1
:
mongosh --host My-Example-Associated-Hostname mongosh --host 198.51.100.1
Example![](/docs/v5.2/assets/link.svg)
Assign a config document to a variable and then to pass the document to
the rs.initiate()
helper:
config = { _id : "my_replica_set", members : [ {_id : 0, host : "rs1.example.net:27017"}, {_id : 1, host : "rs2.example.net:27017"}, {_id : 2, host : "rs3.example.net", arbiterOnly: true}, ] } rs.initiate(config)
Important
To avoid configuration updates due to IP address changes, use DNS hostnames instead of IP addresses. It is particularly important to use a DNS hostname instead of an IP address when configuring replica set members or sharded cluster members.
Use hostnames instead of IP addresses to configure clusters across a split network horizon. Starting in MongDB 5.0, nodes that are only configured with an IP address will fail startup validation and will not start.
Notice that omitting the port cause the host to use the default port
of 27017. Notice also that you can specify other options in the config
documents such as the arbiterOnly
setting in this example.