Configure uniform instance groups

With the instance groups configuration, each node type (master, core, or task) consists of the same instance type and the same purchasing option for instances: On-Demand or Spot. You specify these settings when you create an instance group. They can't be changed later. You can, however, add instances of the same type and purchasing option to core and task instance groups. You can also remove instances.

If the cluster's On-Demand Instances match the attributes of open capacity reservations (instance type, platform, tenancy and Availability Zone) available in your account, the capacity reservations are applied automatically. You can use open capacity reservations for primary, core, and task nodes. However, you cannot use targeted capacity reservations or prevent instances from launching into open capacity reservations with matching attributes when you provision clusters using instance groups. If you want to use targeted capacity reservations or prevent instances from launching into open capacity reservations, use Instance Fleets instead. For more information, see Use capacity reservations with instance fleets.

To add different instance types after a cluster is created, you can add additional task instance groups. You can choose different instance types and purchasing options for each instance group. For more information, see Use Amazon EMR cluster scaling to adjust for changing workloads.

When launching instances, the On-Demand Instance's capacity reservation preference defaults to open, which enables it to run in any open capacity reservation that has matching attributes (instance type, platform, Availability Zone). For more information about On-Demand Capacity Reservations, see Use capacity reservations with instance fleets.

This section covers creating a cluster with uniform instance groups. For more information about modifying an existing instance group by adding or removing instances manually or with automatic scaling, see Manage Amazon EMR clusters.

Use the console to configure uniform instance groups

Console

To create a cluster with instance groups with the new console

1. Sign in to the AWS Management Console, and open the Amazon EMR console at https://console.aws.amazon.com/emr.

2. Under EMR on EC2 in the left navigation pane, choose Clusters, and choose Create cluster.

3. Under Cluster configuration, choose Instance groups.

4. Under Node groups, there is a section for each type of node group. For the primary node group, select the Use multiple primary nodes check box if you want to have 3 primary nodes. Select the Use Spot purchasing option check box if you want to use Spot purchasing.

5. For the primary and core node groups, select Add instance type and choose up to 5 instance types. For the task group, select Add instance type and choose up to fifteen instance types. Amazon EMR might provision any mix of these instance types when it launches the cluster.

6. Under each node group type, choose the Actions dropdown menu next to each instance to change these settings:

   Add EBS volumes

   Specify EBS volumes to attach to the instance type after Amazon EMR provisions it.

   Edit maximum Spot price

   Specify a maximum Spot price for each instance type in a fleet. You can set this price either as a percentage of the On-Demand price, or as a specific dollar amount. If the current Spot price in an Availability Zone is below your maximum Spot price, Amazon EMR provisions Spot Instances. You pay the Spot price, not necessarily the maximum Spot price.

7. Optionally, expand Node configuration to enter a JSON configuration or to load JSON from Amazon S3.

8. Choose any other options that apply to your cluster.

9. To launch your cluster, choose Create cluster.

Use the AWS CLI to create a cluster with uniform instance groups

To specify the instance groups configuration for a cluster using the AWS CLI, use the create-cluster command along with the --instance-groups parameter. Amazon EMR assumes the On-Demand Instance option unless you specify the BidPrice argument for an instance group. For examples of create-cluster commands that launch uniform instance groups with On-Demand Instances and a variety of cluster options, type aws emr create-cluster help at the command line, or see create-cluster in the AWS CLI Command Reference.

You can use the AWS CLI to create uniform instance groups in a cluster that use Spot Instances. The offered Spot price depends on Availability Zone. When you use the CLI or API, you can specify the Availability Zone either with the AvailabilityZone argument (if you're using an EC2-classic network) or the SubnetID argument of the --ec2-attributes parameter. The Availability Zone or subnet that you select applies to the cluster, so it's used for all instance groups. If you don't specify an Availability Zone or subnet explicitly, Amazon EMR selects the Availability Zone with the lowest Spot price when it launches the cluster.

The following example demonstrates a create-cluster command that creates primary, core, and two task instance groups that all use Spot Instances. Replace myKey with the name of your Amazon EC2 key pair.

Note

Linux line continuation characters (\) are included for readability. They can be removed or used in Linux commands. For Windows, remove them or replace with a caret (^).

aws emr create-cluster --name "MySpotCluster" \
  --release-label emr-7.2.0 \
  --use-default-roles \
  --ec2-attributes KeyName=myKey \
  --instance-groups \
    InstanceGroupType=MASTER,InstanceType=m5.xlarge,InstanceCount=1,BidPrice=0.25 \
    InstanceGroupType=CORE,InstanceType=m5.xlarge,InstanceCount=2,BidPrice=0.03 \
    InstanceGroupType=TASK,InstanceType=m5.xlarge,InstanceCount=4,BidPrice=0.03 \
    InstanceGroupType=TASK,InstanceType=m5.xlarge,InstanceCount=2,BidPrice=0.04

Using the CLI, you can create uniform instance group clusters that specify a unique custom AMI for each instance type in the instance group. This allows you to use different instance architectures in the same instance group. Each instance type must use a custom AMI with a matching architecture. For example, you would configure an m5.xlarge instance type with an x86_64 architecture custom AMI, and an m6g.xlarge instance type with a corresponding AWS AARCH64 (ARM) architecture custom AMI.

The following example shows a uniform instance group cluster created with two instance types, each with its own custom AMI. Notice that the custom AMIs are specified only at the instance type level, not at the cluster level. This is to avoid conflicts between the instance type AMIs and an AMI at the cluster level, which would cause the cluster launch to fail.

aws emr create-cluster
  --release-label emr-5.30.0 \
  --service-role EMR_DefaultRole \
  --ec2-attributes SubnetId=subnet-22XXXX01,InstanceProfile=EMR_EC2_DefaultRole \
  --instance-groups \
    InstanceGroupType=MASTER,InstanceType=m5.xlarge,InstanceCount=1,CustomAmiId=ami-123456 \
    InstanceGroupType=CORE,InstanceType=m6g.xlarge,InstanceCount=1,CustomAmiId=ami-234567

You can add multiple custom AMIs to an instance group that you add to a running cluster. The CustomAmiId argument can be used with the add-instance-groups command as shown in the following example.

aws emr add-instance-groups --cluster-id j-123456 \
  --instance-groups \
    InstanceGroupType=Task,InstanceType=m5.xlarge,InstanceCount=1,CustomAmiId=ami-123456

Use the Java SDK to create an instance group

You instantiate an InstanceGroupConfig object that specifies the configuration of an instance group for a cluster. To use Spot Instances, you set the withBidPrice and withMarket properties on the InstanceGroupConfig object. The following code shows how to define primary, core, and task instance groups that run Spot Instances.

InstanceGroupConfig instanceGroupConfigMaster = new InstanceGroupConfig()
	.withInstanceCount(1)
	.withInstanceRole("MASTER")
	.withInstanceType("m4.large")
	.withMarket("SPOT")
	.withBidPrice("0.25"); 
	
InstanceGroupConfig instanceGroupConfigCore = new InstanceGroupConfig()
	.withInstanceCount(4)
	.withInstanceRole("CORE")
	.withInstanceType("m4.large")
	.withMarket("SPOT")
	.withBidPrice("0.03");
	
InstanceGroupConfig instanceGroupConfigTask = new InstanceGroupConfig()
	.withInstanceCount(2)
	.withInstanceRole("TASK")
	.withInstanceType("m4.large")
	.withMarket("SPOT")
	.withBidPrice("0.10");