replSetInitiate
replSetInitiate
- The
replSetInitiate
command initializes a new replica set.
To run replSetInitiate
, use the db.runCommand( { <command> } )
method.
Note
Run the command on only one of the mongod
instancesfor the replica set.
Use the following syntax:
- { replSetInitiate : <config_document> }
The <config_document>
is a document that specifiesthe replica set’s configuration. For instance, here’s a config documentfor creating a simple 3-member replica set:
- {
- _id : <setname>,
- members : [
- {_id : 0, host : <host0>},
- {_id : 1, host : <host1>},
- {_id : 2, host : <host2>},
- ]
- }
Tip
When possible, use a logical DNS hostname instead of an ip address,particularly when configuring replica set members or sharded clustermembers. The use of logical DNS hostnames avoids configurationchanges due to ip address changes.
IP Binding
Starting in MongoDB 3.6, MongoDB binaries, mongod
andmongos
, bind to localhost by default. If thenet.ipv6
configuration file setting or the —ipv6
command line option is set for the binary, the binary additionally bindsto the localhost IPv6 address.
Previously, starting from MongoDB 2.6, only the binaries from theofficial MongoDB RPM (Red Hat, CentOS, Fedora Linux, and derivatives)and DEB (Debian, Ubuntu, and derivatives) packages bind to localhost bydefault.
When bound only to the localhost, these MongoDB 3.6 binaries can onlyaccept connections from clients (including the mongo
shell,other members in your deployment for replica sets and sharded clusters)that are running on the same machine. Remote clients cannot connect tothe binaries bound only to localhost.
To override and bind to other ip addresses, you can use thenet.bindIp
configuration file setting or the—bind_ip
command-line option to specify a list of hostnames or ipaddresses.
Warning
Before binding to a non-localhost (e.g. publicly accessible)IP address, ensure you have secured your cluster from unauthorizedaccess. For a complete list of security recommendations, seeSecurity Checklist. At minimum, considerenabling authentication andhardening network infrastructure.
For example, the following mongod
instance binds to boththe localhost and the hostname My-Example-Associated-Hostname
, which isassociated 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 specifythe hostname or its associated ip address 198.51.100.1
:
- mongo --host My-Example-Associated-Hostname
- mongo --host 198.51.100.1
Example
Assign a config document to a variable and then to pass the document tothe 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)
Tip
When possible, use a logical DNS hostname instead of an ip address,particularly when configuring replica set members or sharded clustermembers. The use of logical DNS hostnames avoids configurationchanges due to ip address changes.
Notice that omitting the port cause the host to use the default portof 27017. Notice also that you can specify other options in the configdocuments such as the arbiterOnly
setting in this example.
See also
Replica Set Configuration,Replica Set Deployment Tutorials, and Replica SetReconfiguration.