AWS Elastic Beanstalk
Developer Guide
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Your AWS Elastic Beanstalk Environment's Amazon EC2 Instances

When you create a web server environment, Elastic Beanstalk creates one or more Amazon Elastic Compute Cloud (Amazon EC2) virtual machines configured to run web apps on the platform that you choose.

The Auto Scaling Group in your environment manages the EC2 instances that run your application. Changes to the Auto Scaling Group's launch configuration require replacement of all instances and will trigger a rolling update or immutable update, depending on which one is configured. For details about configuring the environment's Auto Scaling Group, see Configuring Your Environment's Auto Scaling Group.

Configuring Your Environment's EC2 Instances

You can modify your Elastic Beanstalk environment's EC2 instance configuration in the Elastic Beanstalk console.

To configure EC2 instances in the Elastic Beanstalk console

  1. Open the Elastic Beanstalk console.

  2. Navigate to the management page for your environment.

  3. Choose Configuration.

  4. In the Instances configuration category, choose Modify.

The following settings are available.

Instance Type

The Instance type setting determines the type of EC2 instance launched to run your application. Choose an instance that is powerful enough to run your application under load, but not so powerful that it's idle most of the time. For development purposes, the t2 family of instances provides a moderate amount of power with the ability to burst for short periods of time.

For large-scale, high-availability applications, use a pool of instances to ensure that capacity is not greatly affected if any single instance goes down. Start with an instance type that allows you to run five instances under moderate load during normal hours. If any instance fails, the rest of the instances can absorb the rest of the traffic. The capacity buffer also allows time for the environment to scale up as traffic begins to rise during peak hours.

For more information about EC2 instance families and types, see Instance Types in the Amazon Elastic Compute Cloud User Guide.


The Amazon Machine Image (AMI) is the Amazon Linux or Windows Server machine image that AWS Elastic Beanstalk uses to launch EC2 instances in your environment. Elastic Beanstalk provides machine images that contain the tools and resources required to run your application.

Elastic Beanstalk selects a default AMI for your environment based on the region, platform, and instance type that you choose. If you have created a custom AMI, replace the default AMI ID with yours.

Monitoring Interval

By default, the instances in your environment publish basic health metrics to CloudWatch at five-minute intervals at no additional cost.

For more detailed reporting, you can set the Monitoring interval to 1 minute to increase the frequency with which the resources in your environment publish basic health metrics to CloudWatch. Amazon CloudWatch service charges apply for one-minute interval metrics. See Amazon CloudWatch for more information.

Root Volume (Boot Device)

Each instance in your environment is configured with a root volume. The root volume is the Amazon EBS block device attached to the instance to store the operating system, libraries, scripts, and your application source code. By default, all platforms use general-purpose SSD block devices for storage.

You can modify Root volume type to use magnetic storage or provisioned IOPS SSD volume types and, if needed, increase the volume size. For provisioned IOPS volumes, you must also select the number of IOPS to provision. Select the volume type that meets your performance and price requirements.

For more information, see Amazon EBS Volume Types and Amazon EBS Product Details.

Security Groups

The security groups attached to your instances determine which traffic is allowed to reach the instances (ingress), and which traffic is allowed to leave the instances (egress). Elastic Beanstalk creates a security group that allows traffic from the load balancer on the standard ports for HTTP (80) and HTTPS (443).

You can specify additional security groups that you have created to allow traffic on other ports or from other sources. For example, you can create a security group for SSH access that allows ingress on port 22 from a restricted IP address range or, for additional security, from a bastion host to which only you have access.


To allow traffic between environment A's instances and environment B's instances, you can add a rule to the security group that Elastic Beanstalk attached to environment B, and specify the security group that Elastic Beanstalk attached to environment A. This allows ingress from, or egress to, environment A's instances. However, doing so creates a dependency between the two security groups. If you later try to terminate environment A, Elastic Beanstalk will not be able to delete the environment's security group, because environment B's security group is dependent on it.

A safer approach would be to create a separate security group, attach it to environment A, and specify it in a rule of environment B's security group.

For more information on Amazon EC2 security groups, see Amazon EC2 Security Groups in the Amazon Elastic Compute Cloud User Guide.

The aws:autoscaling:launchconfiguration Namespace

You can use the configuration options in the aws:autoscaling:launchconfiguration namespace to configure your Auto Scaling Group, including additional options that are not available in the console.

The following configuration file configures the basic options shown in this topic, the options EC2KeyName and IamInstanceProfile discussed in Security, and an additional option, BlockDeviceMappings, which isn't available in the console.

option_settings: aws:autoscaling:launchconfiguration: InstanceType: m1.small SecurityGroups: my-securitygroup EC2KeyName: my-keypair MonitoringInterval: "1 minute" IamInstanceProfile: "aws-elasticbeanstalk-ec2-role" BlockDeviceMappings: "/dev/sdj=:100,/dev/sdh=snap-51eef269,/dev/sdb=ephemeral0"

BlockDeviceMappings lets you configure additional block devices for your instances. For more information, see Block Device Mapping in the Amazon Elastic Cloud Computer User Guide.

The EB CLI and Elastic Beanstalk console apply recommended values for the preceding options. You must remove these settings if you want to use configuration files to configure the same. See Recommended Values for details.