Change Hostnames in a Replica Set更改副本集中的主机名

Prerequisites先决条件

The following procedure reads and updates the system.replset collection in the local database.以下过程读取并更新local数据库中的system.replset集合。

If your deployment enforces access control, the user performing the procedure must have find and update privilege actions on the system.replset collection.如果部署强制执行访问控制，则执行该过程的用户必须对system.replset集合具有find和update权限操作。

To create a role that provides the necessary privileges:要创建提供必要权限的角色，请执行以下操作：

1. Log in as a user with privileges to manage users and roles, such as a user with userAdminAnyDatabase role. 以具有管理用户和角色权限的用户身份登录，例如具有userAdminAnyDatabase角色的用户。The following procedure uses the myUserAdmin created in Enable Access Control.以下过程使用在启用访问控制中创建的myUserAdmin。

   mongosh --port 27017 -u myUserAdmin --authenticationDatabase 'admin' -p

2. Create a user role that provides the necessary privileges on the system.replset collection in the local database:创建一个用户角色，为local数据库中的system.replset集合提供必要的权限：

   db.adminCommand( {
      createRole: "systemreplsetRole",
      privileges: [
         { resource: { db: "local", collection: "system.replset" }, actions: ["find","update"] }
      ],
      roles: []
   } );

3. Grant the role to the user who will be performing the rename procedure. 将角色授予将执行重命名过程的用户。For example, the following assumes an existing user "userPerformingRename" in the admin database.例如，以下假设admin数据库中有一个现有用户"userPerformingRename"。

   use admin
   db.grantRolesToUser( "userPerformingRename", [ { role: "systemreplsetRole", db: "admin" } ] );

Procedure过程

1. Stop all members in the replica set.停止复制副本集中的所有成员。
2. Restart each member on a different port and without using the --replSet run-time option. 在不同的端口上重新启动每个成员，而不使用--replSet运行时选项。Changing the port number during maintenance prevents clients from connecting to this host while you perform maintenance. 在维护期间更改端口号可防止客户端在执行维护时连接到此主机。Use the member's usual --dbpath, which in this example is /data/db1. Use a command that resembles the following:使用成员常用的--dbpath，在本例中为/data/db1。使用类似于以下内容的命令：
   Warning

   Before you bind your instance to a publicly-accessible IP address, you must secure your cluster from unauthorized access. 在将实例绑定到可公开访问的IP地址之前，必须保护群集不受未经授权的访问。For a complete list of security recommendations, see Security Checklist. 有关安全建议的完整列表，请参阅安全检查表。At minimum, consider enabling authentication and hardening network infrastructure.至少，考虑启用身份验证和强化网络基础设施。

   mongod --dbpath /data/db1/ --port 37017 --bind_ip localhost,<hostname(s)|ip address(es)>

   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.若要避免由于IP地址更改而导致配置更新，请使用DNS主机名而不是IP地址。在配置复制集成员或分片集群成员时，使用DNS主机名而不是IP地址尤为重要。

   Use hostnames instead of IP addresses to configure clusters across a split network horizon. Starting in MongoDB 5.0, nodes that are only configured with an IP address will fail startup validation and will not start.使用主机名而不是IP地址来跨拆分的网络范围配置群集。从MongoDB 5.0开始，只配置了IP地址的节点将无法通过启动验证，也不会启动。

3. For each member of the replica set, perform the following sequence of operations:对于复制副本集的每个成员，执行以下操作序列：
   1. Connect mongosh to the mongod running on the new, temporary port. 将mongosh连接到在新的临时端口上运行的mongod。For example, for a member running on a temporary port of 37017, you would issue this command:例如，对于在37017的临时端口上运行的成员，您将发出以下命令：

      mongosh --port 37017

      If running with access control, connect as a user with appropriate privileges. 如果使用访问控制运行，请以具有适当权限的用户身份进行连接。See Prerequisites.请参阅先决条件。

      mongosh --port 37017 -u userPerformingRename --authenticationDatabase=admin  -p

   2. Edit the replica set configuration manually. 手动编辑复制副本集配置。The replica set configuration is the only document in the system.replset collection in the local database.副本集配置是local数据库中system.replset集合中的唯一文档。

      To change the hostnames, edit the replica set configuration to provide the new hostnames and ports for all members of the replica set.要更改主机名，请编辑副本集配置，为副本集的所有成员提供新的主机名和端口。

      1. Switch to the local database.切换到local数据库。

         use local

      2. Create a JavaScript variable for the configuration document. 为配置文档创建一个JavaScript变量。Modify the value of the _id field to match your replica set.修改_id字段的值以匹配您的复制副本集。

         cfg = db.system.replset.findOne( { "_id": "rs0" } )

      3. Provide new hostnames and ports for each member of the replica set. Modify the hostnames and ports to match your replica set.为复制副本集的每个成员提供新的主机名和端口。修改主机名和端口以匹配您的复制副本集。

         cfg.members[0].host = "mongodb0.example.net:27017"
         cfg.members[1].host = "mongodb1.example.net:27017"
         cfg.members[2].host = "mongodb2.example.net:27017"

      4. Update the hostnames and ports in the system.replset collection:更新system.replset集合中的主机名和端口：

         db.system.replset.updateOne( { "_id": "rs0" }, { $set: cfg } )

      5. Verify the changes:验证更改：

         db.system.replset.find( {}, { "members.host": 1 } )

   3. Stop the mongod process on the member.停止成员上的mongod进程。
4. After re-configuring all members of the set, start each mongod instance in the normal way: use the usual port number and use the --replSet option. 在重新配置集合的所有成员后，以正常方式启动每个mongod实例：使用通常的端口号并使用--replSet选项。For example:例如：
   Warning

   Before you bind your instance to a publicly-accessible IP address, you must secure your cluster from unauthorized access. 在将实例绑定到可公开访问的IP地址之前，必须保护群集不受未经授权的访问。For a complete list of security recommendations, see Security Checklist. 有关安全建议的完整列表，请参阅安全检查表。At minimum, consider enabling authentication and hardening network infrastructure.至少，考虑启用身份验证和强化网络基础设施。

   mongod --dbpath /data/db1/ --port 27017 --replSet rs0 --bind_ip localhost,<hostname(s)|ip address(es)>

5. Connect to one of the mongod instances using mongosh. 使用mongosh连接到其中一个mongod实例。For example:例如：

   mongosh --port 27017

6. To confirm the new configuration, call rs.conf() in mongosh.要确认新配置，请在mongosh中调用rs.conf()。

   Your output should resemble:您的输出应该类似于：

   {
       "_id" : "rs0",
       "version" : 4,
       "members" : [
           {
               "_id" : 0,
               "host" : "mongodb0.example.net:27017"
           },
           {
               "_id" : 1,
               "host" : "mongodb1.example.net:27017"
           },
           {
               "_id" : 2,
               "host" : "mongodb2.example.net:27017"
           }
       ]
   }