Help Center/ MapReduce Service/ API Reference/ API V2/ Cluster Management APIs/ Scaling Out a Cluster - ExpandCluster
Updated on 2026-09-15 GMT+08:00
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Scaling Out a Cluster - ExpandCluster

Function

This API is used to scale out an MRS cluster by adding nodes to a specified node group. Only MRS clusters in the running state can be scaled out. You can view the scale-out progress by using the cluster details query API. This API works together with the cluster scale-in API to enable dynamic adjustment of cluster capacity.

Constraints

None

Debugging

You can debug this API in API Explorer. Automatic authentication is supported. API Explorer can automatically generate sample SDK code and supports sample SDK code debugging.

Authorization Information

Each account has all the permissions required to call all APIs, but IAM users must be assigned the required permissions.

  • If you are using role/policy-based authorization, see Permissions Policies and Supported Actions for details on the required permissions.
  • If you are using identity policy-based authorization, the following identity policy-based permissions are required.

    Action

    Access Level

    Resource Type (*: required)

    Condition Key

    Alias

    Dependency

    mrs:cluster:resizeNodes

    Write

    cluster *

    • g:ResourceTag/<tag-key>

    • g:EnterpriseProjectId
    • mrs:cluster:resize

    -

URI

POST /v2/{project_id}/clusters/{cluster_id}/expand

Table 1 URI parameters

Parameter

Mandatory

Type

Description

project_id

Yes

String

Definition

Project ID. For details about how to obtain it, see Obtaining a Project ID.

Constraints

N/A

Range

The value can contain 1 to 64 characters. Only letters and digits are allowed.

Default Value

N/A

cluster_id

Yes

String

Definition

Cluster ID. For details about how to obtain it, see Obtaining a Cluster ID.

Constraints

N/A

Range

The value can contain 1 to 64 characters. Only letters, digits, underscores (_), and hyphens (-) are allowed.

Default Value

N/A

Request Parameters

Table 2 Request body parameters

Parameter

Mandatory

Type

Description

node_group_name

Yes

String

Definition

Node group name.

Constraints

N/A

Range

The value can contain 1 to 64 characters, including only letters, digits, underscores (_), and hyphens (-).

Default Value

N/A

count

Yes

Integer

Definition

Number of nodes to add

Constraints

N/A

Range

N/A

Default Value

N/A

skip_bootstrap_scripts

No

Boolean

Definition

Whether to skip the specified bootstrap action during cluster creation on the new node during scale-out.

Constraints

N/A

Range

  • true: The bootstrap action specified during cluster creation is skipped.
  • false: The bootstrap action specified during cluster creation is not skipped.

Default Value

true

scale_without_start

No

Boolean

Definition

Whether the components remain stopped on the added nodes after cluster scale-out.

Constraints

N/A

Range

  • true: Do not start components after scale-out.
  • false: Start components after scale-out.

Default Value

false

Response Parameters

Status code: 200

Table 3 Response body parameter

Parameter

Type

Description

result

String

Definition

Result of the request. Value succeeded indicates that the operation is successful, and value failed indicates that the operation fails. This parameter is returned when a request for scaling out a non-yearly/monthly node group is successfully delivered.

Range

  • succeeded: The operation is successful.
  • failed: The operation failed.

order_id

String

Definition

Order ID. When you scale out a yearly/monthly node group, the order ID generated during the scale-out is returned. You need to pay for the order to trigger the scale-out.

Range

N/A

Example Request

  • Scale out the node group node_group_1 by adding one node. Skip bootstrap actions and start components by default. 
    /v2/ff8080828997cb24018a1b2db3440b80/clusters/f7f45c04-4303-411c-9b71-d2cb730dd162/expand 

 { 
   "node_group_name" : "node_group_1", 
   "count" : "1" 
 }
  • Scale out the node group node_group_1 by adding one node. Do not skip bootstrap actions or start components. 
    /v2/ff8080828997cb24018a1b2db3440b80/clusters/f7f45c04-4303-411c-9b71-d2cb730dd162/expand 
  
 { 
   "node_group_name" : "node_group_1", 
   "count" : "1", 
   "skip_bootstrap_scripts" : false, 
   "scale_without_start" : true 
 }

Example Response

Status code: 200

The response body varies depending on the billing mode of node groups. The order ID is returned for you to settle payment for scaling out a yearly/monthly node group.

  • A pay-per-use node group is scaled out successfully. 
    {
  "result" : "succeeded"
}
  • A yearly/monthly node group is scaled out successfully. The ID of the order you need to pay is CS231XXXXXXXXXXX. 
    {
  "order_id" : "CS231XXXXXXXXXXX"
}

SDK Sample Code

The SDK sample code is as follows.

  • Scale out the node group node_group_1 by adding one node. Skip bootstrap actions and start components by default.

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    package com.huaweicloud.sdk.test;

import com.huaweicloud.sdk.core.auth.ICredential;
import com.huaweicloud.sdk.core.auth.BasicCredentials;
import com.huaweicloud.sdk.core.exception.ConnectionException;
import com.huaweicloud.sdk.core.exception.RequestTimeoutException;
import com.huaweicloud.sdk.core.exception.ServiceResponseException;
import com.huaweicloud.sdk.mrs.v2.region.MrsRegion;
import com.huaweicloud.sdk.mrs.v2.*;
import com.huaweicloud.sdk.mrs.v2.model.*;


public class ExpandClusterSolution {

    public static void main(String[] args) {
        // The AK and SK used for authentication are hard-coded or stored in plaintext, which has great security risks. It is recommended that the AK and SK be stored in ciphertext in configuration files or environment variables and decrypted during use to ensure security.
        // In this example, AK and SK are stored in environment variables for authentication. Before running this example, set environment variables CLOUD_SDK_AK and CLOUD_SDK_SK in the local environment
        String ak = System.getenv("CLOUD_SDK_AK");
        String sk = System.getenv("CLOUD_SDK_SK");
        String projectId = "{project_id}";

        ICredential auth = new BasicCredentials()
                .withProjectId(projectId)
                .withAk(ak)
                .withSk(sk);

        MrsClient client = MrsClient.newBuilder()
                .withCredential(auth)
                .withRegion(MrsRegion.valueOf("<YOUR REGION>"))
                .build();
        ExpandClusterRequest request = new ExpandClusterRequest();
        request.withClusterId("{cluster_id}");
        ExpandParam body = new ExpandParam();
        body.withCount(1);
        body.withNodeGroupName("node_group_1");
        request.withBody(body);
        try {
            ExpandClusterResponse response = client.expandCluster(request);
            System.out.println(response.toString());
        } catch (ConnectionException e) {
            e.printStackTrace();
        } catch (RequestTimeoutException e) {
            e.printStackTrace();
        } catch (ServiceResponseException e) {
            e.printStackTrace();
            System.out.println(e.getHttpStatusCode());
            System.out.println(e.getRequestId());
            System.out.println(e.getErrorCode());
            System.out.println(e.getErrorMsg());
        }
    }
}

  • Scale out the node group node_group_1 by adding one node. Do not skip bootstrap actions or start components.

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    package com.huaweicloud.sdk.test;

import com.huaweicloud.sdk.core.auth.ICredential;
import com.huaweicloud.sdk.core.auth.BasicCredentials;
import com.huaweicloud.sdk.core.exception.ConnectionException;
import com.huaweicloud.sdk.core.exception.RequestTimeoutException;
import com.huaweicloud.sdk.core.exception.ServiceResponseException;
import com.huaweicloud.sdk.mrs.v2.region.MrsRegion;
import com.huaweicloud.sdk.mrs.v2.*;
import com.huaweicloud.sdk.mrs.v2.model.*;


public class ExpandClusterSolution {

    public static void main(String[] args) {
        // The AK and SK used for authentication are hard-coded or stored in plaintext, which has great security risks. It is recommended that the AK and SK be stored in ciphertext in configuration files or environment variables and decrypted during use to ensure security.
        // In this example, AK and SK are stored in environment variables for authentication. Before running this example, set environment variables CLOUD_SDK_AK and CLOUD_SDK_SK in the local environment
        String ak = System.getenv("CLOUD_SDK_AK");
        String sk = System.getenv("CLOUD_SDK_SK");
        String projectId = "{project_id}";

        ICredential auth = new BasicCredentials()
                .withProjectId(projectId)
                .withAk(ak)
                .withSk(sk);

        MrsClient client = MrsClient.newBuilder()
                .withCredential(auth)
                .withRegion(MrsRegion.valueOf("<YOUR REGION>"))
                .build();
        ExpandClusterRequest request = new ExpandClusterRequest();
        request.withClusterId("{cluster_id}");
        ExpandParam body = new ExpandParam();
        body.withScaleWithoutStart(true);
        body.withSkipBootstrapScripts(false);
        body.withCount(1);
        body.withNodeGroupName("node_group_1");
        request.withBody(body);
        try {
            ExpandClusterResponse response = client.expandCluster(request);
            System.out.println(response.toString());
        } catch (ConnectionException e) {
            e.printStackTrace();
        } catch (RequestTimeoutException e) {
            e.printStackTrace();
        } catch (ServiceResponseException e) {
            e.printStackTrace();
            System.out.println(e.getHttpStatusCode());
            System.out.println(e.getRequestId());
            System.out.println(e.getErrorCode());
            System.out.println(e.getErrorMsg());
        }
    }
}

  • Scale out the node group node_group_1 by adding one node. Skip bootstrap actions and start components by default.

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    # coding: utf-8

import os
from huaweicloudsdkcore.auth.credentials import BasicCredentials
from huaweicloudsdkmrs.v2.region.mrs_region import MrsRegion
from huaweicloudsdkcore.exceptions import exceptions
from huaweicloudsdkmrs.v2 import *

if __name__ == "__main__":
    # The AK and SK used for authentication are hard-coded or stored in plaintext, which has great security risks. It is recommended that the AK and SK be stored in ciphertext in configuration files or environment variables and decrypted during use to ensure security.
    # In this example, AK and SK are stored in environment variables for authentication. Before running this example, set environment variables CLOUD_SDK_AK and CLOUD_SDK_SK in the local environment
    ak = os.environ["CLOUD_SDK_AK"]
    sk = os.environ["CLOUD_SDK_SK"]
    projectId = "{project_id}"

    credentials = BasicCredentials(ak, sk, projectId)

    client = MrsClient.new_builder() \
        .with_credentials(credentials) \
        .with_region(MrsRegion.value_of("<YOUR REGION>")) \
        .build()

    try:
        request = ExpandClusterRequest()
        request.cluster_id = "{cluster_id}"
        request.body = ExpandParam(
            count=1,
            node_group_name="node_group_1"
        )
        response = client.expand_cluster(request)
        print(response)
    except exceptions.ClientRequestException as e:
        print(e.status_code)
        print(e.request_id)
        print(e.error_code)
        print(e.error_msg)

  • Scale out the node group node_group_1 by adding one node. Do not skip bootstrap actions or start components.

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    # coding: utf-8

import os
from huaweicloudsdkcore.auth.credentials import BasicCredentials
from huaweicloudsdkmrs.v2.region.mrs_region import MrsRegion
from huaweicloudsdkcore.exceptions import exceptions
from huaweicloudsdkmrs.v2 import *

if __name__ == "__main__":
    # The AK and SK used for authentication are hard-coded or stored in plaintext, which has great security risks. It is recommended that the AK and SK be stored in ciphertext in configuration files or environment variables and decrypted during use to ensure security.
    # In this example, AK and SK are stored in environment variables for authentication. Before running this example, set environment variables CLOUD_SDK_AK and CLOUD_SDK_SK in the local environment
    ak = os.environ["CLOUD_SDK_AK"]
    sk = os.environ["CLOUD_SDK_SK"]
    projectId = "{project_id}"

    credentials = BasicCredentials(ak, sk, projectId)

    client = MrsClient.new_builder() \
        .with_credentials(credentials) \
        .with_region(MrsRegion.value_of("<YOUR REGION>")) \
        .build()

    try:
        request = ExpandClusterRequest()
        request.cluster_id = "{cluster_id}"
        request.body = ExpandParam(
            scale_without_start=True,
            skip_bootstrap_scripts=False,
            count=1,
            node_group_name="node_group_1"
        )
        response = client.expand_cluster(request)
        print(response)
    except exceptions.ClientRequestException as e:
        print(e.status_code)
        print(e.request_id)
        print(e.error_code)
        print(e.error_msg)

  • Scale out the node group node_group_1 by adding one node. Skip bootstrap actions and start components by default.

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    package main

import (
	"fmt"
	"github.com/huaweicloud/huaweicloud-sdk-go-v3/core/auth/basic"
    mrs "github.com/huaweicloud/huaweicloud-sdk-go-v3/services/mrs/v2"
	"github.com/huaweicloud/huaweicloud-sdk-go-v3/services/mrs/v2/model"
    region "github.com/huaweicloud/huaweicloud-sdk-go-v3/services/mrs/v2/region"
)

func main() {
    // The AK and SK used for authentication are hard-coded or stored in plaintext, which has great security risks. It is recommended that the AK and SK be stored in ciphertext in configuration files or environment variables and decrypted during use to ensure security.
    // In this example, AK and SK are stored in environment variables for authentication. Before running this example, set environment variables CLOUD_SDK_AK and CLOUD_SDK_SK in the local environment
    ak := os.Getenv("CLOUD_SDK_AK")
    sk := os.Getenv("CLOUD_SDK_SK")
    projectId := "{project_id}"

    auth, err := basic.NewCredentialsBuilder().
        WithAk(ak).
        WithSk(sk).
        WithProjectId(projectId).
        SafeBuild()

    if err != nil {
        fmt.Println(err)
        return
    }

    hcClient, err := mrs.MrsClientBuilder().
         WithRegion(region.ValueOf("<YOUR REGION>")).
         WithCredential(auth).
         SafeBuild()


    if err != nil {
        fmt.Println(err)
        return
    }

    client := mrs.NewMrsClient(hcClient)

    request := &model.ExpandClusterRequest{}
	request.ClusterId = "{cluster_id}"
	request.Body = &model.ExpandParam{
		Count: int32(1),
		NodeGroupName: "node_group_1",
	}
	response, err := client.ExpandCluster(request)
	if err == nil {
        fmt.Printf("%+v\n", response)
    } else {
        fmt.Println(err)
    }
}

  • Scale out the node group node_group_1 by adding one node. Do not skip bootstrap actions or start components.

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    package main

import (
	"fmt"
	"github.com/huaweicloud/huaweicloud-sdk-go-v3/core/auth/basic"
    mrs "github.com/huaweicloud/huaweicloud-sdk-go-v3/services/mrs/v2"
	"github.com/huaweicloud/huaweicloud-sdk-go-v3/services/mrs/v2/model"
    region "github.com/huaweicloud/huaweicloud-sdk-go-v3/services/mrs/v2/region"
)

func main() {
    // The AK and SK used for authentication are hard-coded or stored in plaintext, which has great security risks. It is recommended that the AK and SK be stored in ciphertext in configuration files or environment variables and decrypted during use to ensure security.
    // In this example, AK and SK are stored in environment variables for authentication. Before running this example, set environment variables CLOUD_SDK_AK and CLOUD_SDK_SK in the local environment
    ak := os.Getenv("CLOUD_SDK_AK")
    sk := os.Getenv("CLOUD_SDK_SK")
    projectId := "{project_id}"

    auth, err := basic.NewCredentialsBuilder().
        WithAk(ak).
        WithSk(sk).
        WithProjectId(projectId).
        SafeBuild()

    if err != nil {
        fmt.Println(err)
        return
    }

    hcClient, err := mrs.MrsClientBuilder().
         WithRegion(region.ValueOf("<YOUR REGION>")).
         WithCredential(auth).
         SafeBuild()


    if err != nil {
        fmt.Println(err)
        return
    }

    client := mrs.NewMrsClient(hcClient)

    request := &model.ExpandClusterRequest{}
	request.ClusterId = "{cluster_id}"
	scaleWithoutStartExpandParam:= true
	skipBootstrapScriptsExpandParam:= false
	request.Body = &model.ExpandParam{
		ScaleWithoutStart: &scaleWithoutStartExpandParam,
		SkipBootstrapScripts: &skipBootstrapScriptsExpandParam,
		Count: int32(1),
		NodeGroupName: "node_group_1",
	}
	response, err := client.ExpandCluster(request)
	if err == nil {
        fmt.Printf("%+v\n", response)
    } else {
        fmt.Println(err)
    }
}

For SDK sample code of more programming languages, see the Sample Code tab in API Explorer. SDK sample code can be automatically generated.

Status Codes

Status Code

Description

200

For pay-per-use and yearly/monthly node group scale-out operations, different response bodies are returned. For yearly/monthly node groups, an order ID is returned. A payment must be made based on the order ID before the scale-out can actually proceed.

Error Codes

For details, see Error Codes.

Parent Topic: Cluster Management APIs