# AddInstanceGroups
Adds one or more instance groups to a running cluster.
## Request Syntax
```
{
"InstanceGroups": [
{
"AutoScalingPolicy": {
"Constraints": {
"MaxCapacity": {{number}},
"MinCapacity": {{number}}
},
"Rules": [
{
"Action": {
"Market": "{{string}}",
"SimpleScalingPolicyConfiguration": {
"AdjustmentType": "{{string}}",
"CoolDown": {{number}},
"ScalingAdjustment": {{number}}
}
},
"Description": "{{string}}",
"Name": "{{string}}",
"Trigger": {
"CloudWatchAlarmDefinition": {
"ComparisonOperator": "{{string}}",
"Dimensions": [
{
"Key": "{{string}}",
"Value": "{{string}}"
}
],
"EvaluationPeriods": {{number}},
"MetricName": "{{string}}",
"Namespace": "{{string}}",
"Period": {{number}},
"Statistic": "{{string}}",
"Threshold": {{number}},
"Unit": "{{string}}"
}
}
}
]
},
"BidPrice": "{{string}}",
"Configurations": [
{
"Classification": "{{string}}",
"Configurations": [
"Configuration"
],
"Properties": {
"{{string}}" : "{{string}}"
}
}
],
"CustomAmiId": "{{string}}",
"EbsConfiguration": {
"EbsBlockDeviceConfigs": [
{
"VolumeSpecification": {
"Iops": {{number}},
"SizeInGB": {{number}},
"Throughput": {{number}},
"VolumeType": "{{string}}"
},
"VolumesPerInstance": {{number}}
}
],
"EbsOptimized": {{boolean}}
},
"InstanceCount": {{number}},
"InstanceRole": "{{string}}",
"InstanceType": "{{string}}",
"Market": "{{string}}",
"Name": "{{string}}"
}
],
"JobFlowId": "{{string}}"
}
```
## Request Parameters
For information about the parameters that are common to all actions, see [Common Parameters](CommonParameters.md).
The request accepts the following data in JSON format.
** [InstanceGroups](#API_AddInstanceGroups_RequestSyntax) **
Instance groups to add.
Type: Array of [InstanceGroupConfig](API_InstanceGroupConfig.md) objects
Required: Yes
** [JobFlowId](#API_AddInstanceGroups_RequestSyntax) **
Job flow in which to add the instance groups.
Type: String
Length Constraints: Minimum length of 0. Maximum length of 256.
Pattern: `[\u0020-\uD7FF\uE000-\uFFFD\uD800\uDC00-\uDBFF\uDFFF\r\n\t]*`
Required: Yes
## Response Syntax
```
{
"ClusterArn": "string",
"InstanceGroupIds": [ "string" ],
"JobFlowId": "string"
}
```
## Response Elements
If the action is successful, the service sends back an HTTP 200 response.
The following data is returned in JSON format by the service.
** [ClusterArn](#API_AddInstanceGroups_ResponseSyntax) **
The Amazon Resource Name of the cluster.
Type: String
Length Constraints: Minimum length of 20. Maximum length of 2048.
** [InstanceGroupIds](#API_AddInstanceGroups_ResponseSyntax) **
Instance group IDs of the newly created instance groups.
Type: Array of strings
Length Constraints: Minimum length of 0. Maximum length of 256.
Pattern: `[\u0020-\uD7FF\uE000-\uFFFD\uD800\uDC00-\uDBFF\uDFFF\r\n\t]*`
** [JobFlowId](#API_AddInstanceGroups_ResponseSyntax) **
The job flow ID in which the instance groups are added.
Type: String
Length Constraints: Minimum length of 0. Maximum length of 256.
Pattern: `[\u0020-\uD7FF\uE000-\uFFFD\uD800\uDC00-\uDBFF\uDFFF\r\n\t]*`
## Errors
For information about the errors that are common to all actions, see [Common Error Types](CommonErrors.md).
** InternalServerError **
Indicates that an error occurred while processing the request and that the request was not completed.
HTTP Status Code: 400
## Examples
### Example
This example illustrates one usage of AddInstanceGroups.
#### Sample Request
```
POST / HTTP/1.1
Content-Type: application/x-amz-json-1.1
X-Amz-Target: ElasticMapReduce.AddInstanceGroups
Content-Length: 168
User-Agent: aws-sdk-ruby/1.9.2 ruby/1.9.3 i386-mingw32
Host: us-east-1.elasticmapreduce.amazonaws.com
X-Amz-Date: 20130715T223346Z
X-Amz-Content-Sha256: ac5a7193b1283898dd822a4b16ca36963879bb010d2dbe57198439973ab2a7d3
Authorization: AWS4-HMAC-SHA256 Credential=AKIAIOSFODNN7EXAMPLE/20130715/us-east-1/elasticmapreduce/aws4_request, SignedHeaders=content-length;content-type;host;user-agent;x-amz-content-sha256;x-amz-date;x-amz-target, Signature=4c5e7eb762ea45f292a5cd1a1cc56ed60009e19a9dba3d6e5e4e67e96d43af11
Accept: */*
{
"JobFlowId": "j-3U7TSX5GZFD8Y",
"InstanceGroups": [{
"Name": "Task Instance Group",
"InstanceRole": "TASK",
"InstanceCount": 2,
"InstanceType": "m1.small",
"Market": "ON_DEMAND"
}]
}
```
#### Sample Response
```
HTTP/1.1 200 OK
x-amzn-RequestId: 9da5a349-ed9e-11e2-90db-69a5154aeb8d
Content-Type: application/x-amz-json-1.1
Content-Length: 71
Date: Mon, 15 Jul 2013 22:33:47 GMT
{
"InstanceGroupIds": ["ig-294A6A2KWT4WB"],
"JobFlowId": "j-3U7TSX5GZFD8Y"
}
```
## See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
+ [AWS Command Line Interface V2](https://docs.aws.amazon.com/goto/cli2/elasticmapreduce-2009-03-31/AddInstanceGroups)
+ [AWS SDK for .NET V4](https://docs.aws.amazon.com/goto/DotNetSDKV4/elasticmapreduce-2009-03-31/AddInstanceGroups)
+ [AWS SDK for C\+\+](https://docs.aws.amazon.com/goto/SdkForCpp/elasticmapreduce-2009-03-31/AddInstanceGroups)
+ [AWS SDK for Go v2](https://docs.aws.amazon.com/goto/SdkForGoV2/elasticmapreduce-2009-03-31/AddInstanceGroups)
+ [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/elasticmapreduce-2009-03-31/AddInstanceGroups)
+ [AWS SDK for JavaScript V3](https://docs.aws.amazon.com/goto/SdkForJavaScriptV3/elasticmapreduce-2009-03-31/AddInstanceGroups)
+ [AWS SDK for Kotlin](https://docs.aws.amazon.com/goto/SdkForKotlin/elasticmapreduce-2009-03-31/AddInstanceGroups)
+ [AWS SDK for PHP V3](https://docs.aws.amazon.com/goto/SdkForPHPV3/elasticmapreduce-2009-03-31/AddInstanceGroups)
+ [AWS SDK for Python](https://docs.aws.amazon.com/goto/boto3/elasticmapreduce-2009-03-31/AddInstanceGroups)
+ [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/elasticmapreduce-2009-03-31/AddInstanceGroups)