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

Function

This API is used to scale in an MRS cluster by removing nodes from a specified node group.

Two scale-in methods are supported: scale-in by quantity, where the system automatically selects the nodes to be deleted, and scale-in by specifying nodes, which supports deleting ECS nodes in an abnormal state. You can view the scale-in progress by using the cluster details query API.

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}/shrink

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

No

Integer

Definition

Number of nodes to remove.

Constraints

If nodes are specified for scale-in, this parameter can be left blank.

Range

N/A

Default Value

N/A

resource_ids

No

Array of strings

Definition

List of resource IDs of the nodes to be deleted during scale-in. The node ID information (resource_id) can be obtained by using the host query API.

Constraints

  • If left blank, the system automatically selects nodes for deletion based on system rules.
  • Only ECS nodes in an abnormal state can be deleted.
  • The specified nodes will be forcibly deleted.

Range

N/A

Default Value

N/A

Response Parameters

Status code: 200

Table 3 Response body parameter

Parameter

Type

Description

result

String

Definition

Scale-in result.

Range

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

Example Request

  • Remove one node from the node group node_group_1. 
    /v2/ff8080828997cb24018a1b2db3440b80/clusters/f7f45c04-4303-411c-9b71-d2cb730dd162/shrink

{
  "node_group_name" : "node_group_1",
  "count" : 1
}
  • Forcibly remove the node with resource ID 678050cd-ba1d-4550-942d-f2e396b1c6fb from node group node_group_1. 
    /v2/ff8080828997cb24018a1b2db3440b80/clusters/f7f45c04-4303-411c-9b71-d2cb730dd162/shrink

{
  "node_group_name" : "node_group_1",
  "resource_ids" : [ "678050cd-ba1d-4550-942d-f2e396b1c6fb" ]
}

Example Response

Status code: 200

The scale-in is successful.

{
  "result" : "succeeded"
}

SDK Sample Code

The SDK sample code is as follows.

  • Remove one node from the node group node_group_1.

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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 ShrinkClusterSolution {

    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();
        ShrinkClusterRequest request = new ShrinkClusterRequest();
        request.withClusterId("{cluster_id}");
        ShrinkParam body = new ShrinkParam();
        body.withCount(1);
        body.withNodeGroupName("node_group_1");
        request.withBody(body);
        try {
            ShrinkClusterResponse response = client.shrinkCluster(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());
        }
    }
}

  • Forcibly remove the node with resource ID 678050cd-ba1d-4550-942d-f2e396b1c6fb from node group node_group_1.

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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.*;

import java.util.List;
import java.util.ArrayList;

public class ShrinkClusterSolution {

    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();
        ShrinkClusterRequest request = new ShrinkClusterRequest();
        request.withClusterId("{cluster_id}");
        ShrinkParam body = new ShrinkParam();
        List<String> listbodyResourceIds = new ArrayList<>();
        listbodyResourceIds.add("678050cd-ba1d-4550-942d-f2e396b1c6fb");
        body.withResourceIds(listbodyResourceIds);
        body.withNodeGroupName("node_group_1");
        request.withBody(body);
        try {
            ShrinkClusterResponse response = client.shrinkCluster(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());
        }
    }
}

  • Remove one node from the node group node_group_1.

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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 = ShrinkClusterRequest()
        request.cluster_id = "{cluster_id}"
        request.body = ShrinkParam(
            count=1,
            node_group_name="node_group_1"
        )
        response = client.shrink_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)

  • Forcibly remove the node with resource ID 678050cd-ba1d-4550-942d-f2e396b1c6fb from node group node_group_1.

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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 = ShrinkClusterRequest()
        request.cluster_id = "{cluster_id}"
        listResourceIdsbody = [
            "678050cd-ba1d-4550-942d-f2e396b1c6fb"
        ]
        request.body = ShrinkParam(
            resource_ids=listResourceIdsbody,
            node_group_name="node_group_1"
        )
        response = client.shrink_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)

  • Remove one node from the node group node_group_1.

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

  • Forcibly remove the node with resource ID 678050cd-ba1d-4550-942d-f2e396b1c6fb from node group node_group_1.

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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.ShrinkClusterRequest{}
	request.ClusterId = "{cluster_id}"
	var listResourceIdsbody = []string{
        "678050cd-ba1d-4550-942d-f2e396b1c6fb",
    }
	request.Body = &model.ShrinkParam{
		ResourceIds: &listResourceIdsbody,
		NodeGroupName: "node_group_1",
	}
	response, err := client.ShrinkCluster(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

Scale-in succeeded.

Error Codes

For details, see Error Codes.

Parent Topic: Cluster Management APIs