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	Project ID. For details about how to obtain the project ID, see Obtaining a Project ID.
cluster_id	Yes	String	Cluster ID For details about how to obtain the cluster ID, see Obtaining the MRS Cluster Information.

Request Parameters

**Table 2** Request body parameters
Parameter	Mandatory	Type	Description
node_group	Yes	String	Type of the node to which an auto scaling rule applies. Currently, only Task nodes support auto scaling rules, that is, the request value is task_node_default_group.
auto_scaling_policy	Yes	AutoScalingPolicy object	The auto scaling policy. Table 3 describes these parameters.

**Table 3** AutoScalingPolicy object parameters
Parameter	Mandatory	Type	Description
auto_scaling_enable	Yes	Boolean	Whether to enable the auto scaling rule.
min_capacity	Yes	Integer	Minimum number of nodes left in the node group. Value range: 0 to 500
max_capacity	Yes	Integer	Maximum number of nodes in the node group. Value range: 0 to 500
resources_plans	No	List	Resource plan list. For details, see Table 4. If this parameter is left blank, the resource plan is disabled. When auto scaling is enabled, either a resource plan or an auto scaling rule must be configured.
exec_scripts	No	List	List of custom scaling automation scripts. For details, see Table 5. If this parameter is left blank, a hook script is disabled.
rules	No	List	List of auto scaling rules. For details, see Table 6. When auto scaling is enabled, either a resource plan or an auto scaling rule must be configured.

**Table 4** resources_plan parameters
Parameter	Mandatory	Type	Description
period_type	Yes	String	Cycle type of a resource plan. Currently, only the following cycle type is supported: daily
start_time	Yes	String	Start time of a resource plan. The value is in the format of hour:minute, indicating that the time ranges from 0:00 to 23:59.
end_time	Yes	String	End time of a resource plan. The value is in the same format as that of start_time. The interval between end_time and start_time must be greater than or equal to 30 minutes.
min_capacity	Yes	Integer	Minimum number of the preserved nodes in a node group in a resource plan. Value range: 0 to 500
max_capacity	Yes	Integer	Maximum number of the preserved nodes in a node group in a resource plan. Value range: 0 to 500

**Table 5** exec_script parameters
Parameter	Mandatory	Type	Description
name	Yes	String	Name of a custom automation script. It must be unique in a same cluster. 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.
uri	Yes	String	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.
parameters	No	String	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.
nodes	Yes	Array of strings	Type of a node where the custom automation script is executed. The node type can be Master, Core, or Task.
active_master	No	Boolean	Whether the custom automation script runs only on the active Master node. The default value is false, indicating that the custom automation script can run on all Master nodes.
action_stage	Yes	String	Time when a script is executed. The following four options are supported: before_scale_out: before scale-out before_scale_in: before scale-in after_scale_out: after scale-out after_scale_in: after scale-in
fail_action	Yes	String	Whether to continue to execute subsequent scripts and create a cluster after the custom automation script fails to be executed. continue: Continue to execute subsequent scripts. errorout: Stop the action. 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** rules parameters
Parameter	Mandatory	Type	Description
name	Yes	String	Name of an auto scaling rule. 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.
description	No	String	Description about an auto scaling rule. It contains a maximum of 1,024 characters.
adjustment_type	Yes	String	Auto scaling rule adjustment type. Possible values: scale_out: cluster scale-out scale_in: cluster scale-in
cool_down_minutes	Yes	Integer	Cluster cooling time after an auto scaling rule is triggered, when no auto scaling operation is performed. The unit is minute. Value range: 0 to 10,080. One week is equal to 10,080 minutes.
scaling_adjustment	Yes	Integer	Number of nodes that can be adjusted once. Value range: 1 to 100
trigger	Yes	Trigger object	Condition for triggering a rule. For details, see Table 7.

**Table 7** trigger parameters
Parameter	Mandatory	Type	Description
metric_name	Yes	String	Metric name. This triggering condition makes a judgment according to the value of the metric. A metric name contains a maximum of 64 characters.
metric_value	Yes	String	Metric threshold to trigger a rule The parameter value can be an integer or number with two decimal places only.
comparison_operator	No	String	Metric judgment logic operator. Possible values: LT: less than GT: greater than LTOE: less than or equal to GTOE: greater than or equal to
evaluation_periods	Yes	Integer	Number of consecutive five-minute periods, during which a metric threshold is reached Value range: 1 to 288

Response Parameters

**Table 8** Response parameter
Parameter	Type	Description
result	String	Operation result succeeded: The operation is successful.

Example

Example request

{
  "node_group":"task_node_default_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": "",
         "nodes": [
           "master",
           "core",
           "task"
         ],
         "active_master": "true",
         "action_stage": "before_scale_out",
         "fail_action": "continue"
         },{
         "name": "after_scale_out",
         "uri": "s3a://XXX/storm_rebalance.sh",
         "parameters": "",
         "nodes": [
           "master",
           "core",
           "task"
         ],
         "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.