Configuring an Auto Scaling Rule

Function

This API is used to configure auto scaling rules.

The API used for cluster creation and job execution can also be used to create an auto scaling rule.

URI

Format
POST /v1.1/{project_id}/autoscaling-policy/{cluster_id}

Parameter description

**Table 1** URI parameters
Parameter	Mandatory	Type	Description
project_id	Yes	String	Explanation Project ID. For details about how to obtain the project ID, see Obtaining a Project ID. Constraints N/A Value range The value must consist of 1 to 64 characters. Only letters and digits are allowed. Default value N/A
cluster_id	Yes	String	Explanation Cluster ID For details about how to obtain the cluster ID, see Obtaining the MRS Cluster Information. Constraints N/A Value range The value can contain 1 to 64 characters, including only letters, digits, underscores (_), and hyphens (-). Default value N/A

Request Parameters

**Table 2** Request body parameters
Parameter	Mandatory	Type	Description
node_group	Yes	String	Explanation Type of the node to which an auto scaling rule applies. Currently, only task nodes support auto scaling rules. Constraints N/A Value range task_node_default_group: Task node Default value N/A
auto_scaling_policy	Yes	AutoScalingPolicy object	Explanation The auto scaling policy. Table 3 describes these parameters. Constraints N/A

**Table 3** AutoScalingPolicy
Parameter	Mandatory	Type	Description
auto_scaling_enable	Yes	Boolean	Explanation Whether to enable the auto scaling rule. Constraints N/A Value range true: Enable the auto scaling rule. false: Disable the autoscaling rule. Default value N/A
min_capacity	Yes	Integer	Explanation Minimum number of nodes left in the node group. Constraints N/A Value range 0-500 Default value N/A
max_capacity	Yes	Integer	Explanation Maximum number of nodes in the node group. Constraints N/A Value range 0-500 Default value N/A
resources_plans	No	List	Explanation Resource plan list. For details, see Table 4. If this parameter is left blank, the resource plan is disabled. Constraints When auto scaling is enabled, either a resource plan or an auto scaling rule must be configured.
exec_scripts	No	List	Explanation List of custom scaling automation scripts. For details, see Table 5. If this parameter is left blank, a hook script is disabled. Constraints The number of records cannot exceed 10.
rules	No	List	Explanation List of auto scaling rules. For details, see Table 6. Constraints When auto scaling is enabled, either a resource plan or an auto scaling rule must be configured. The number of records cannot exceed 10.

**Table 4** ResourcesPlan
Parameter	Mandatory	Type	Description
period_type	Yes	String	Explanation Cycle type of a resource plan. This parameter can be set to daily only. Constraints N/A Value range N/A Default value N/A
start_time	Yes	String	Explanation Start time of a resource plan. The value is in the format of hour:minute. Constraints N/A Value range N/A Default value N/A
end_time	Yes	String	Explanation End time of a resource plan. The format is the same as that of start_time. Constraints The value cannot be earlier than the start_time, and the interval between start_time and start_time cannot be less than 30 minutes. Value range N/A Default value N/A
min_capacity	Yes	Integer	Explanation Minimum number of the preserved nodes in a node group in a resource plan. Constraints N/A Value range 0-500 Default value N/A
max_capacity	Yes	Integer	Explanation Maximum number of the preserved nodes in a node group in a resource plan. Constraints N/A Value range 0-500 Default value N/A

**Table 5** ScaleScript
Parameter	Mandatory	Type	Description
name	Yes	String	Explanation Names of custom scaling automation scripts. Constraints N/A Value range The names in the same cluster must be unique. The value can contain only digits, letters, spaces, hyphens (-), and underscores (_) and must not start with a space. The value can contain 1 to 64 characters. Default value N/A
uri	Yes	String	Explanation Path of a custom automation script. Set this parameter to an OBS bucket path or a local VM path. OBS bucket path: Enter a script path manually. for example, s3a://XXX/scale.sh. Local VM path: Enter a script path. The script path must start with a slash (/) and end with .sh. Constraints N/A Value range N/A Default value N/A
parameters	No	String	Explanation Parameters of a custom automation script. Multiple parameters are separated by space. The following predefined system parameters can be transferred: ${mrs_scale_node_num}: Number of the nodes to be added or removed ${mrs_scale_type}: Scaling type. The value can be scale_out or scale_in. ${mrs_scale_node_hostnames}: Host names of the nodes to be added or removed ${mrs_scale_node_ips}: IP addresses of the nodes to be added or removed ${mrs_scale_rule_name}: Name of the rule that triggers auto scaling Other user-defined parameters are used in the same way as those of common shell scripts. Parameters are separated by space. Constraints N/A Value range N/A Default value N/A
nodes	Yes	Array of strings	Explanation Type of a node where the custom automation script is executed. The node type can be Master, Core, or Task. Constraints N/A
active_master	No	Boolean	Explanation Whether the custom automation script runs only on the active Master node. Constraints N/A Value range true: The custom automation script runs only on the active Master nodes. false: The custom automation script can run on all Master nodes. Default value false
action_stage	Yes	String	Explanation Time when a script is executed. Constraints N/A Value range before_scale_out: before scale-out before_scale_in: before scale-in after_scale_out: after scale-out after_scale_in: after scale-in Default value N/A
fail_action	Yes	String	Explanation Whether to continue to execute subsequent scripts and create a cluster after the custom automation script fails to be executed. Constraints N/A Value range continue: Continue to execute subsequent scripts. errorout: Stop the action. Default value N/A NOTE: You are advised to set this parameter to continue in the commissioning phase so that the cluster can continue to be installed and started no matter whether the custom automation script is executed successfully. The scale-in operation cannot be undone. Therefore, fail_action must be set to continue for the scripts that are executed after scale-in.

**Table 6** Rule
Parameter	Mandatory	Type	Description
name	Yes	String	Explanation Name of an auto scaling rule. Constraints N/A Value range A cluster name can contain only 1 to 64 characters. Only letters, digits, hyphens (-), and underscores (_) are allowed. Rule names must be unique in a node group. Default value N/A
description	No	String	Explanation Description about an auto scaling rule. Constraints N/A Value range A string of 1 to 1024 characters Default value N/A
adjustment_type	Yes	String	Explanation Adjustment type of an auto scaling rule. Constraints N/A Value range scale_out: cluster scale-out scale_in: cluster scale-in Default value N/A
cool_down_minutes	Yes	Integer	Explanation Cluster cooling time after an auto scaling rule is triggered, when no auto scaling operation is performed. The unit is minute. Constraints N/A Value range 0 to 10080. 10080 indicates the number of minutes in a week. Default value N/A
scaling_adjustment	Yes	Integer	Explanation Number of nodes that can be adjusted once. Constraints N/A Value range 1-100 Default value N/A
trigger	Yes	Trigger object	Explanation Condition for triggering a rule. For details, see Table 7. Constraints N/A

**Table 7** Trigger
Parameter	Mandatory	Type	Description
metric_name	Yes	String	Explanation Metric name. This triggering condition makes a judgment according to the value of the metric. Constraints N/A Value range The value contains a maximum of 64 characters. Default value N/A
metric_value	Yes	String	Explanation Metric threshold to trigger a rule The value must be an integer or a number with two decimal places. Constraints N/A Value range Only integers or numbers with two decimal places are allowed. Default value N/A
comparison_operator	No	String	Explanation Metric judgment logic operator. Constraints N/A Value range LT: less than GT: greater than LTOE: less than or equal to GTOE: greater than or equal to Default value N/A
evaluation_periods	Yes	Integer	Explanation Number of consecutive five-minute periods, during which a metric threshold is reached Constraints N/A Value range 1-200 Default value N/A

Response Parameters

None

Example Request

Configure an auto scaling policy for the MRS cluster.

POST https://{endpoint}/v1.1/{project_id}/autoscaling-policy/{cluster_id}

{
  "node_group" : "task_node_analysis_group",
  "auto_scaling_policy" : {
    "auto_scaling_enable" : "true",
    "min_capacity" : "1",
    "max_capacity" : "3",
    "resources_plans" : [ {
      "period_type" : "daily",
      "start_time" : "9:50",
      "end_time" : "10:20",
      "min_capacity" : "2",
      "max_capacity" : "3"
    }, {
      "period_type" : "daily",
      "start_time" : "10:20",
      "end_time" : "12:30",
      "min_capacity" : "0",
      "max_capacity" : "2"
    } ],
    "exec_scripts" : [ {
      "name" : "before_scale_out",
      "uri" : "s3a://XXX/zeppelin_install.sh",
      "parameters" : "${mrs_scale_node_num} ${mrs_scale_type} xxx",
      "nodes" : [ "master_node_default_group", "core_node_analysis_group", "task_node_analysis_group" ],
      "active_master" : "true",
      "action_stage" : "before_scale_out",
      "fail_action" : "continue"
    }, {
      "name" : "after_scale_out",
      "uri" : "s3a://XXX/storm_rebalance.sh",
      "parameters" : "${mrs_scale_node_hostnames} ${mrs_scale_node_ips}",
      "nodes" : [ "master_node_default_group", "core_node_analysis_group", "task_node_analysis_group" ],
      "active_master" : "true",
      "action_stage" : "after_scale_out",
      "fail_action" : "continue"
    } ],
    "rules" : [ {
      "name" : "default-expand-1",
      "adjustment_type" : "scale_out",
      "cool_down_minutes" : "5",
      "scaling_adjustment" : "1",
      "trigger" : {
        "metric_name" : "YARNMemoryAvailablePercentage",
        "metric_value" : "25",
        "comparison_operator" : "LT",
        "evaluation_periods" : "10"
      }
    }, {
      "name" : "default-shrink-1",
      "adjustment_type" : "scale_in",
      "cool_down_minutes" : "5",
      "scaling_adjustment" : "1",
      "trigger" : {
        "metric_name" : "YARNMemoryAvailablePercentage",
        "metric_value" : "70",
        "comparison_operator" : "GT",
        "evaluation_periods" : "10"
      }
    } ]
  }
}

A new auto scaling rule will overwrite the auto scaling rule saved in the original database. If you want to modify the original rule, query the original rule first, modify the rule, and submit a modification task. For details, see Querying Cluster Details.