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Managing MySQL® cluster hosts

Written by
Updated at May 5, 2025

You can add and remove cluster hosts and manage their settings. For information about moving cluster hosts to a different availability zone, see this guide.

Getting a list of cluster hosts

  1. Go to the folder page and select Managed Service for MySQL.
  2. Click the name of the cluster you need and select the Hosts tab.

If you do not have the Yandex Cloud CLI yet, install and initialize it.

The folder specified when creating the CLI profile is used by default. To change the default folder, use the yc config set folder-id <folder_ID> command. You can specify a different folder using the --folder-name or --folder-id parameter.

To get a list of cluster hosts, run the command:

yc managed-mysql host list \
   --cluster-name=<cluster_name>

Result:

+----------------------------+----------------------+---------+--------+---------------+
|            NAME            |      CLUSTER ID      |  ROLE   | HEALTH |    ZONE ID    |
+----------------------------+----------------------+---------+--------+---------------+
| rc1b...mdb.yandexcloud.net | c9q5k4ve7ev4******** | MASTER  | ALIVE  | ru-central1-b |
| rc1a...mdb.yandexcloud.net | c9q5k4ve7ev4******** | REPLICA | ALIVE  | ru-central1-a |
+----------------------------+----------------------+---------+--------+---------------+

You can request the cluster name with a list of clusters in the folder.

  1. Get an IAM token for API authentication and put it into the environment variable:

    export IAM_TOKEN="<IAM_token>"

  2. Use the Cluster.listHosts method and make a request, e.g., via cURL:

    curl \
    --request GET \
    --header "Authorization: Bearer $IAM_TOKEN" \
    --url 'https://mdb.api.cloud.yandex.net/managed-mysql/v1/clusters/<cluster_ID>/hosts'

    You can get the cluster ID with a list of clusters in the folder.

  3. View the server response to make sure the request was successful.

  1. Get an IAM token for API authentication and put it into the environment variable:

    export IAM_TOKEN="<IAM_token>"

  2. Clone the cloudapi repository:

    cd ~/ && git clone --depth=1 https://github.com/yandex-cloud/cloudapi

    Below, we assume the repository contents are stored in the ~/cloudapi/ directory.

  3. Use the ClusterService/ListHosts call and make a request, e.g., via gRPCurl:

    grpcurl \
    -format json \
    -import-path ~/cloudapi/ \
    -import-path ~/cloudapi/third_party/googleapis/ \
    -proto ~/cloudapi/yandex/cloud/mdb/mysql/v1/cluster_service.proto \
    -rpc-header "Authorization: Bearer $IAM_TOKEN" \
    -d '{
          "cluster_id": "<cluster_ID>"
        }' \
    mdb.api.cloud.yandex.net:443 \
    yandex.cloud.mdb.mysql.v1.ClusterService.ListHosts

    You can get the cluster ID with a list of clusters in the folder.

  4. View the server response to make sure the request was successful.

Adding a host

The number of hosts in Managed Service for MySQL® clusters is limited by the CPU and RAM quotas available to DB clusters in your cloud. To check the resources currently in use, open the Quotas page and find Managed Databases.

  1. Go to the folder page and select Managed Service for MySQL.

  2. Click the cluster name and go to the Hosts tab.

  3. Click Create host.

  4. Specify the host parameters:

    • Availability zone.

    • Subnet (if the required subnet is not on the list, create it).

    • Select Public access if the host must be accessible from outside Yandex Cloud.

    • Priority for assigning the host as a master.

    • Host priority as a MySQL® replica for creating backups.

If you do not have the Yandex Cloud CLI yet, install and initialize it.

The folder specified when creating the CLI profile is used by default. To change the default folder, use the yc config set folder-id <folder_ID> command. You can specify a different folder using the --folder-name or --folder-id parameter.

To add a host to a cluster:

  1. Request a list of cluster subnets to select one for the new host:

    yc vpc subnet list

    Result:

    +----------------------+-----------+-----------------------+---------------+------------------+
|          ID          |   NAME    |       NETWORK ID      |       ZONE    |      RANGE       |
+----------------------+-----------+-----------------------+---------------+------------------+
| b0cl69a2b4c6******** | default-d | enp6rq72rndgr******** | ru-central1-d | [172.**.*.*/20]  |
| e2lkj9qwe762******** | default-b | enp6rq72rndgr******** | ru-central1-b | [10.**.*.*/16]   |
| e9b0ph42bn96******** | a-2       | enp6rq72rndgr******** | ru-central1-a | [172.**.**.*/20] |
| e9b9v22r88io******** | default-a | enp6rq72rndgr******** | ru-central1-a | [172.**.**.*/20] |
+----------------------+-----------+-----------------------+---------------+------------------+

    If the required subnet is not in the list, create it.

  2. View a description of the CLI command for adding a host:

    yc managed-mysql host add --help

  3. Run the add host command (the example does not show all the available parameters):

    yc managed-mysql host add \
  --cluster-name=<cluster_name> \
  --host zone-id=<availability_zone_ID>,`
    `subnet-id=<subnet_ID>,`
    `assign-public-ip=<public_access_to_subcluster_host>,`
    `replication-source=<source_host_name>,`
    `backup-priority=<host_backup_priority>,`
    `priority=<priority_for_assigning_host_as_master>

    Where:

    • --cluster-name: Managed Service for MySQL® cluster name.
    • --host: Host parameters:
      • zone-id: Availability zone.
      • subnet-id: Subnet ID. Specify if two or more subnets are created in the selected availability zone.
      • assign-public-ip: Host accessibility from the internet, true or false..
      • replication-source: Replication source for the host.
      • backup-priority: Host's backup priority, between 0 and 100.
      • priority: Priority for assigning the host as master if the primary master fails, between 0 and 100.

    You can request the cluster name with a list of clusters in the folder.

  1. Open the current Terraform configuration file with an infrastructure plan.

    For more information about creating this file, see Creating clusters.

  2. Add a host block to the Managed Service for MySQL® cluster description:

    resource "yandex_mdb_mysql_cluster" "<cluster_name>" {
  ...
  host {
    zone             = "<availability_zone>"
    subnet_id        = <subnet_ID>
    assign_public_ip = <public_access_to_host>
    priority         = <priority_for_assigning_host_as_master>
    ...
  }
}

    Where:

    • assign_public_ip: Public access to the host, true or false.
    • priority: Priority of assigning the host as master, between 0 and 100.

  3. Make sure the settings are correct.

    1. In the command line, navigate to the directory that contains the current Terraform configuration files defining the infrastructure.

    2. Run this command:

      terraform validate

      Terraform will show any errors found in your configuration files.

  4. Confirm updating the resources.

    1. Run this command to view the planned changes:

      terraform plan

      If you described the configuration correctly, the terminal will display a list of the resources to update and their parameters. This is a verification step that does not apply changes to your resources.

    2. If everything looks correct, apply the changes:

      1. Run this command:

        terraform apply

      2. Confirm updating the resources.

      3. Wait for the operation to complete.

For more information, see the Terraform provider documentation.

Time limits

A Terraform provider sets the timeout for Managed Service for MySQL® cluster operations:

  • Creating a cluster, including by restoring one from a backup: 15 minutes.
  • Editing a cluster, including the MySQL® version update: 60 minutes.
  • Deleting a cluster: 15 minutes.

Operations exceeding the set timeout are interrupted.

How do I change these limits?

Add the timeouts block to the cluster description, for example:

resource "yandex_mdb_mysql_cluster" "<cluster_name>" {
  ...
  timeouts {
    create = "1h30m" # 1 hour 30 minutes
    update = "2h"    # 2 hours
    delete = "30m"   # 30 minutes
  }
}

  1. Get an IAM token for API authentication and put it into the environment variable:

    export IAM_TOKEN="<IAM_token>"

  2. Use the Cluster.addHosts method and make a request, e.g., via cURL:

    curl \
    --request POST \
    --header "Authorization: Bearer $IAM_TOKEN" \
    --header "Content-Type: application/json" \
    --url 'https://mdb.api.cloud.yandex.net/managed-mysql/v1/clusters/<cluster_ID>/hosts:batchCreate' \
    --data '{
              "hostSpecs": [
                {
                  "zoneId": "<availability_zone>",
                  "subnetId": "<subnet_ID>",
                  "assignPublicIp": <public_host_address:_true_or_false>,
                  "replicationSource": "<host_FQDN>",
                  "backupPriority": "<host_backup_priority>",
                  "priority": "<priority_for_assigning_host_as_master>"
                }
              ]
            }'

    Where hostSpecs is an array of new hosts. One array element contains settings for a single host and has the following structure:

    • zoneId: Availability zone.
    • subnetId: Subnet ID.
    • assignPublicIp: Internet access to the host via a public IP address.
    • replicationSource: Replication source for the host to manually manage replication threads. In the parameter, specify the FQDN of the host to be used as a replication source.
    • backupPriority: Host's backup priority, between 0 and 100.
    • priority: Priority for assigning the host as master if the primary master fails, between 0 and 100.

    You can get the cluster ID with a list of clusters in the folder.

  3. View the server response to make sure the request was successful.

  1. Get an IAM token for API authentication and put it into the environment variable:

    export IAM_TOKEN="<IAM_token>"

  2. Clone the cloudapi repository:

    cd ~/ && git clone --depth=1 https://github.com/yandex-cloud/cloudapi

    Below, we assume the repository contents are stored in the ~/cloudapi/ directory.

  3. Use the ClusterService/AddHosts call and make a request, e.g., via gRPCurl:

    grpcurl \
    -format json \
    -import-path ~/cloudapi/ \
    -import-path ~/cloudapi/third_party/googleapis/ \
    -proto ~/cloudapi/yandex/cloud/mdb/mysql/v1/cluster_service.proto \
    -rpc-header "Authorization: Bearer $IAM_TOKEN" \
    -d '{
          "cluster_id": "<cluster_ID>",
          "host_specs": [
            {
              "zone_id": "<availability_zone>",
              "subnet_id": "<subnet_ID>",
              "assign_public_ip": <public_host_address:_true_or_false>,
              "replication_source": "<host_FQDN>",
              "backup_priority": "<host_backup_priority>",
              "priority": "<priority_for_assigning_host_as_master>"
            }
          ]
        }' \
    mdb.api.cloud.yandex.net:443 \
    yandex.cloud.mdb.mysql.v1.ClusterService.AddHosts

    Where host_specs is an array of new hosts. One array element contains settings for a single host and has the following structure:

    • zone_id: Availability zone.
    • subnet_id: Subnet ID.
    • assign_public_ip: Internet access to the host via a public IP address.
    • replication_source: Replication source for the host to manually manage replication threads. In the parameter, specify the FQDN of the host to be used as a replication source.
    • backup_priority: Host's backup priority, between 0 and 100.
    • priority: Priority for assigning the host as master if the primary master fails, between 0 and 100.

    You can get the cluster ID with a list of clusters in the folder.

  4. View the server response to make sure the request was successful.

Warning

If you cannot connect to the host you added, check that the cluster security group is configured correctly for the host's subnet.

Changing a host

For each host in a Managed Service for MySQL® cluster, you can:

Note

You cannot restart a separate cluster host. To restart hosts, stop and restart the cluster.

To change the parameters of the cluster host:

  1. Go to the folder page and select Managed Service for MySQL.
  2. Click the cluster name and open the Hosts tab.
  3. Click in the host row and select Edit.
  4. Set new settings for the host:
    1. Select a replication source for the host to control replication threads manually.
    2. Enable Public access if the host must be accessible from outside Yandex Cloud.
    3. Set the value of the Master priority field.
    4. Set the value of the Backup priority field.
  5. Click Save.

If you do not have the Yandex Cloud CLI yet, install and initialize it.

The folder specified when creating the CLI profile is used by default. To change the default folder, use the yc config set folder-id <folder_ID> command. You can specify a different folder using the --folder-name or --folder-id parameter.

To modify host parameters, execute the command below (the parameter list in the example is not exhaustive):

yc managed-mysql host update <host_name> \
  --cluster-name=<cluster_name> \
  --replication-source=<source_host_name> \
  --assign-public-ip=<public_access_to_host> \
  --backup-priority=<host_backup_priority> \
  --priority=<priority_for_assigning_host_as_master>

Where:

  • --cluster-name: Managed Service for MySQL® cluster name.
  • --replication-source: Replication source for the host.
  • --assign-public-ip: Host accessibility from the internet, true or false.
  • --backup-priority: Host's backup priority, between 0 and 100.
  • --priority: Priority for assigning the host as master if the primary master fails, between 0 and 100.

You can request the host name with a list of cluster hosts, and the cluster name, with a list of clusters in the folder.

To change the parameters of the cluster host:

  1. Open the current Terraform configuration file with an infrastructure plan.

    For more information about creating this file, see Creating clusters.

  2. In the Managed Service for MySQL® cluster description, change the attributes of the host block corresponding to the host you are updating.

    resource "yandex_mdb_mysql_cluster" "<cluster_name>" {
  ...
  host {
    replication_source_name = "<replication_source>"
    assign_public_ip        = <public_access_to_host>
    priority                = <priority_for_assigning_host_as_master>
  }
}

    Where:

    • assign_public_ip: Public access to the host, true or false.
    • priority: Priority of assigning the host as master, between 0 and 100.

  3. Make sure the settings are correct.

    1. In the command line, navigate to the directory that contains the current Terraform configuration files defining the infrastructure.

    2. Run this command:

      terraform validate

      Terraform will show any errors found in your configuration files.

  4. Confirm updating the resources.

    1. Run this command to view the planned changes:

      terraform plan

      If you described the configuration correctly, the terminal will display a list of the resources to update and their parameters. This is a verification step that does not apply changes to your resources.

    2. If everything looks correct, apply the changes:

      1. Run this command:

        terraform apply

      2. Confirm updating the resources.

      3. Wait for the operation to complete.

For more information, see the Terraform provider documentation.

Time limits

A Terraform provider sets the timeout for Managed Service for MySQL® cluster operations:

  • Creating a cluster, including by restoring one from a backup: 15 minutes.
  • Editing a cluster, including the MySQL® version update: 60 minutes.
  • Deleting a cluster: 15 minutes.

Operations exceeding the set timeout are interrupted.

How do I change these limits?

Add the timeouts block to the cluster description, for example:

resource "yandex_mdb_mysql_cluster" "<cluster_name>" {
  ...
  timeouts {
    create = "1h30m" # 1 hour 30 minutes
    update = "2h"    # 2 hours
    delete = "30m"   # 30 minutes
  }
}

  1. Get an IAM token for API authentication and put it into the environment variable:

    export IAM_TOKEN="<IAM_token>"

  2. Use the Cluster.updateHosts method and make a request, e.g., via cURL:

    curl \
    --request POST \
    --header "Authorization: Bearer $IAM_TOKEN" \
    --header "Content-Type: application/json" \
    --url 'https://mdb.api.cloud.yandex.net/managed-mysql/v1/clusters/<cluster_ID>/hosts:batchUpdate' \
    --data '{
              "updateHostSpecs": [
                {
                  "updateMask": "assignPublicIp,replicationSource,backupPriority,priority",
                  "hostName": "<host_FQDN>",
                  "assignPublicIp": <public_host_address:_true_or_false>,
                  "replicationSource": "<host_FQDN>",
                  "backupPriority": "<host_backup_priority>",
                  "priority": "<priority_for_assigning_host_as_master>"
                }
              ]
            }'

    Where updateHostSpecs is an array of hosts being changed. One array element contains settings for a single host and has the following structure:

    You can get the cluster ID with a list of clusters in the folder.

  3. View the server response to make sure the request was successful.

  1. Get an IAM token for API authentication and put it into the environment variable:

    export IAM_TOKEN="<IAM_token>"

  2. Clone the cloudapi repository:

    cd ~/ && git clone --depth=1 https://github.com/yandex-cloud/cloudapi

    Below, we assume the repository contents are stored in the ~/cloudapi/ directory.

  3. Use the ClusterService/UpdateHosts call and make a request, e.g., via gRPCurl:

    grpcurl \
    -format json \
    -import-path ~/cloudapi/ \
    -import-path ~/cloudapi/third_party/googleapis/ \
    -proto ~/cloudapi/yandex/cloud/mdb/mysql/v1/cluster_service.proto \
    -rpc-header "Authorization: Bearer $IAM_TOKEN" \
    -d '{
          "cluster_id": "<cluster_ID>",
          "update_host_specs": [
            {
              "update_mask": {
                "paths": [
                  "assign_public_ip", "replication_source", "backup_priority", "priority"
                ]
              },
              "host_name": "<host_FQDN>",
              "assign_public_ip": <public_host_address:_true_or_false>,
              "replication_source": "<host_FQDN>",
              "backup_priority": "<host_backup_priority>",
              "priority": "<priority_for_assigning_host_as_master>"
            }
          ]
        }' \
    mdb.api.cloud.yandex.net:443 \
    yandex.cloud.mdb.mysql.v1.ClusterService.UpdateHosts

    Where update_host_specs is an array of hosts being changed. One array element contains settings for a single host and has the following structure:

    You can get the cluster ID with a list of clusters in the folder.

  4. View the server response to make sure the request was successful.

Warning

If you cannot connect to the host after you changed it, check that the cluster security group is configured correctly for the host's subnet.

Removing a host

You can remove a host from a MySQL® cluster if it is not the only host in it. To replace a single host, first create a new host and then remove the old one.

If the host is the master when deleted, Managed Service for MySQL® automatically assigns the replica of the next highest priority as the master.

  1. Go to the folder page and select Managed Service for MySQL.
  2. Click the cluster name and open the Hosts tab.
  3. Click in the host row and select Delete.

If you do not have the Yandex Cloud CLI yet, install and initialize it.

The folder specified when creating the CLI profile is used by default. To change the default folder, use the yc config set folder-id <folder_ID> command. You can specify a different folder using the --folder-name or --folder-id parameter.

To remove a host from the cluster, run:

yc managed-mysql host delete <host_name> \
   --cluster-name=<cluster_name>

You can request the host name with a list of cluster hosts, and the cluster name, with a list of clusters in the folder.

  1. Open the current Terraform configuration file with an infrastructure plan.

    For more information about creating this file, see Creating clusters.

  2. Delete the host block from the Managed Service for MySQL® cluster description.

  3. Make sure the settings are correct.

    1. In the command line, navigate to the directory that contains the current Terraform configuration files defining the infrastructure.

    2. Run this command:

      terraform validate

      Terraform will show any errors found in your configuration files.

  4. Type yes and press Enter.

    1. Run this command to view the planned changes:

      terraform plan

      If you described the configuration correctly, the terminal will display a list of the resources to update and their parameters. This is a verification step that does not apply changes to your resources.

    2. If everything looks correct, apply the changes:

      1. Run this command:

        terraform apply

      2. Confirm updating the resources.

      3. Wait for the operation to complete.

For more information, see the Terraform provider documentation.

Time limits

A Terraform provider sets the timeout for Managed Service for MySQL® cluster operations:

  • Creating a cluster, including by restoring one from a backup: 15 minutes.
  • Editing a cluster, including the MySQL® version update: 60 minutes.
  • Deleting a cluster: 15 minutes.

Operations exceeding the set timeout are interrupted.

How do I change these limits?

Add the timeouts block to the cluster description, for example:

resource "yandex_mdb_mysql_cluster" "<cluster_name>" {
  ...
  timeouts {
    create = "1h30m" # 1 hour 30 minutes
    update = "2h"    # 2 hours
    delete = "30m"   # 30 minutes
  }
}

  1. Get an IAM token for API authentication and put it into the environment variable:

    export IAM_TOKEN="<IAM_token>"

  2. Use the Cluster.deleteHosts method and make a request, e.g., via cURL:

    curl \
    --request POST \
    --header "Authorization: Bearer $IAM_TOKEN" \
    --header "Content-Type: application/json" \
    --url 'https://mdb.api.cloud.yandex.net/managed-mysql/v1/clusters/<cluster_ID>/hosts:batchDelete' \
    --data '{
              "hostNames": [
                "<host_FQDN>"
              ]
            }'

    Where hostNames is an array with the host to delete.

    Only one host FQDN can be provided in a single request. If you need to delete multiple hosts, run the request for each of them.

    You can get the cluster ID with a list of clusters in the folder.

  3. View the server response to make sure the request was successful.

  1. Get an IAM token for API authentication and put it into the environment variable:

    export IAM_TOKEN="<IAM_token>"

  2. Clone the cloudapi repository:

    cd ~/ && git clone --depth=1 https://github.com/yandex-cloud/cloudapi

    Below, we assume the repository contents are stored in the ~/cloudapi/ directory.

  3. Use the ClusterService/DeleteHosts call and make a request, e.g., via gRPCurl:

    grpcurl \
    -format json \
    -import-path ~/cloudapi/ \
    -import-path ~/cloudapi/third_party/googleapis/ \
    -proto ~/cloudapi/yandex/cloud/mdb/mysql/v1/cluster_service.proto \
    -rpc-header "Authorization: Bearer $IAM_TOKEN" \
    -d '{
          "cluster_id": "<cluster_ID>",
          "host_names": [
            "<host_FQDN>"
          ]
        }' \
    mdb.api.cloud.yandex.net:443 \
    yandex.cloud.mdb.mysql.v1.ClusterService.DeleteHosts

    Where host_names is an array with the host to delete.

    Only one host FQDN can be provided in a single request. If you need to delete multiple hosts, run the request for each of them.

    You can get the cluster ID with a list of clusters in the folder.

  4. View the server response to make sure the request was successful.

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Stopping and starting a cluster
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Migrating hosts to a different availability zone