InstanceGroupManagers: resizeAdvanced

Requires authorization

Resizes the managed instance group with advanced configuration options like disabling creation retries. This is an extended version of the resize method.

If you increase the size of the instance group, the group creates new instances using the current instance template. If you decrease the size, the group deletes instances. The resize operation is marked DONE when the resize actions are scheduled even if the group has not yet added or deleted any instances. You must separately verify the status of the creating, creatingWithoutRetries, or deleting actions with the get or listmanagedinstances method.

If the group is part of a backend service that has enabled connection draining, it can take up to 60 seconds after the connection draining duration has elapsed before the VM instance is removed or deleted.


HTTP request



Parameter name Value Description
Path parameters
instanceGroupManager string The name of the managed instance group.
project string Project ID for this request.
zone string The name of the zone where the managed instance group is located.
Optional query parameters
requestId string An optional request ID to identify requests. Specify a unique request ID so that if you must retry your request, the server will know to ignore the request if it has already been completed.

For example, consider a situation where you make an initial request and the request times out. If you make the request again with the same request ID, the server can check if original operation with the same request ID was received, and if so, will ignore the second request. This prevents clients from accidentally creating duplicate commitments.

The request ID must be a valid UUID with the exception that zero UUID is not supported (00000000-0000-0000-0000-000000000000).


This request requires authorization with at least one of the following scopes (read more about authentication and authorization).


Request body

In the request body, supply data with the following structure:

  "targetSize": integer,
  "noCreationRetries": boolean
Property name Value Description Notes
targetSize integer The number of running instances that the managed instance group should maintain at any given time. The group automatically adds or removes instances to maintain the number of instances specified by this parameter.
noCreationRetries boolean If this flag is true, the managed instance group attempts to create all instances initiated by this resize request only once. If there is an error during creation, the managed instance group does not retry create this instance, and we will decrease the targetSize of the request instead. If the flag is false, the group attemps to recreate each instance continuously until it succeeds.

This flag matters only in the first attempt of creation of an instance. After an instance is successfully created while this flag is enabled, the instance behaves the same way as all the other instances created with a regular resize request. In particular, if a running instance dies unexpectedly at a later time and needs to be recreated, this mode does not affect the recreation behavior in that scenario.

This flag is applicable only to the current resize request. It does not influence other resize requests in any way.

You can see which instances is being creating in which mode by calling the get or listManagedInstances API.


If successful, this method returns a response body with the following structure:

  "kind": "compute#operation",
  "id": unsigned long,
  "creationTimestamp": string,
  "name": string,
  "zone": string,
  "clientOperationId": string,
  "operationType": string,
  "targetLink": string,
  "targetId": unsigned long,
  "status": string,
  "statusMessage": string,
  "user": string,
  "progress": integer,
  "insertTime": string,
  "startTime": string,
  "endTime": string,
  "error": {
    "errors": [
        "code": string,
        "location": string,
        "message": string
  "warnings": [
      "code": string,
      "message": string,
      "data": [
          "key": string,
          "value": string
  "httpErrorStatusCode": integer,
  "httpErrorMessage": string,
  "selfLink": string,
  "region": string,
  "description": string
Property name Value Description Notes
kind string [Output Only] Type of the resource. Always compute#operation for Operation resources.
id unsigned long [Output Only] The unique identifier for the resource. This identifier is defined by the server.
creationTimestamp string [Deprecated] This field is deprecated.
name string [Output Only] Name of the resource.
zone string [Output Only] The URL of the zone where the operation resides. Only available when performing per-zone operations.
clientOperationId string [Output Only] Reserved for future use.
operationType string [Output Only] The type of operation, such as insert, update, or delete, and so on.
targetId unsigned long [Output Only] The unique target ID, which identifies a specific incarnation of the target resource.
status string [Output Only] The status of the operation, which can be one of the following: PENDING, RUNNING, or DONE.
statusMessage string [Output Only] An optional textual description of the current status of the operation.
user string [Output Only] User who requested the operation, for example:
progress integer [Output Only] An optional progress indicator that ranges from 0 to 100. There is no requirement that this be linear or support any granularity of operations. This should not be used to guess when the operation will be complete. This number should monotonically increase as the operation progresses.
insertTime string [Output Only] The time that this operation was requested. This value is in RFC3339 text format.
startTime string [Output Only] The time that this operation was started by the server. This value is in RFC3339 text format.
endTime string [Output Only] The time that this operation was completed. This value is in RFC3339 text format.
error object [Output Only] If errors are generated during processing of the operation, this field will be populated.
error.errors[] list [Output Only] The array of errors encountered while processing this operation.
error.errors[].code string [Output Only] The error type identifier for this error.
error.errors[].location string [Output Only] Indicates the field in the request that caused the error. This property is optional.
error.errors[].message string [Output Only] An optional, human-readable error message.
warnings[] list [Output Only] If warning messages are generated during processing of the operation, this field will be populated.
warnings[].code string [Output Only] A warning code, if applicable. For example, Compute Engine returns NO_RESULTS_ON_PAGE if there are no results in the response.
warnings[].message string [Output Only] A human-readable description of the warning code.
warnings[].data[] list [Output Only] Metadata about this warning in key: value format. For example:
"data": [ { "key": "scope", "value": "zones/us-east1-d" }
warnings[].data[].key string [Output Only] A key that provides more detail on the warning being returned. For example, for warnings where there are no results in a list request for a particular zone, this key might be scope and the key value might be the zone name. Other examples might be a key indicating a deprecated resource and a suggested replacement, or a warning about invalid network settings (for example, if an instance attempts to perform IP forwarding but is not enabled for IP forwarding).
warnings[].data[].value string [Output Only] A warning data value corresponding to the key.
httpErrorStatusCode integer [Output Only] If the operation fails, this field contains the HTTP error status code that was returned. For example, a 404 means the resource was not found.
httpErrorMessage string [Output Only] If the operation fails, this field contains the HTTP error message that was returned, such as NOT FOUND.
region string [Output Only] The URL of the region where the operation resides. Only available when performing regional operations.
description string [Output Only] A textual description of the operation, which is set when the operation is created.

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