Working with burstable performance instances

The steps for launching, monitoring, and modifying these instances are similar. The key difference is the default credit specification when they launch. If you do not change the default credit specification, the default is that:

• T3 instances launch as unlimited

• T2 instances launch as standard

Launching a burstable performance instance as Unlimited or Standard

You can launch your instances as unlimited or standard using the Amazon EC2 console, an AWS SDK, a command line tool, or with an Auto Scaling group. For more information, see Using an Auto Scaling group to launch a burstable performance instance as Unlimited.

To launch a burstable performance instance as Unlimited or Standard (console)

1. Follow the Launching an instance using the Launch Instance Wizard procedure.

2. On the Choose an Instance Type page, select an instance type, and choose Next: Configure Instance Details.

3. Choose a credit specification.

   1. To launch a T3 instance as standard, clear Unlimited.

   2. To launch a T2 instance as unlimited, select Unlimited.

4. Continue as prompted by the wizard. When you've finished reviewing your options on the Review Instance Launch page, choose Launch. For more information, see Launching an instance using the Launch Instance Wizard.

To launch a burstable performance instance as Unlimited or Standard (AWS CLI)

Use the run-instances command to launch your instances. Specify the credit specification using the --credit-specification CpuCredits= parameter. Valid credit specifications are unlimited and standard.

• For T3, if you do not include the --credit-specification parameter, the instance launches as unlimited by default.

• For T2, if you do not include the --credit-specification parameter, the instance launches as standard by default.

aws ec2 run-instances --image-id ami-abc12345 --count 1 --instance-type t3.micro --key-name MyKeyPair --credit-specification "CpuCredits=unlimited"

Using an Auto Scaling group to launch a burstable performance instance as Unlimited

When burstable performance instances are launched or started, they require CPU credits for a good bootstrapping experience. If you use an Auto Scaling group to launch your instances, we recommend that you configure your instances as unlimited. If you do, the instances use surplus credits when they are automatically launched or restarted by the Auto Scaling group. Using surplus credits prevents performance restrictions.

Creating a launch template

You must use a launch template for launching instances as unlimited in an Auto Scaling group. A launch configuration does not support launching instances as unlimited.

To create a launch template that launches instances as Unlimited (console)

1. Follow the Creating a Launch Template for an Auto Scaling Group procedure.

2. In Launch template contents, for Instance type, choose an instance size.

3. To launch instances as unlimited in an Auto Scaling group, under Advanced details, for Credit specification, choose Unlimited.

4. When you've finished defining the launch template parameters, choose Create launch template. For more information, see Creating a Launch Template for an Auto Scaling Group in the Amazon EC2 Auto Scaling User Guide.

To create a launch template that launches instances as Unlimited (AWS CLI)

Use the create-launch-template command and specify unlimited as the credit specification.

• For T3, if you do not include the CreditSpecification={CpuCredits=unlimited} value, the instance launches as unlimited by default.

• For T2, if you do not include the CreditSpecification={CpuCredits=unlimited} value, the instance launches as standard by default.

aws ec2 create-launch-template --launch-template-name MyLaunchTemplate --version-description FirstVersion --launch-template-data ImageId=ami-8c1be5f6,InstanceType=t3.medium,CreditSpecification={CpuCredits=unlimited}

Associating an Auto Scaling group with a launch template

To associate the launch template with an Auto Scaling group, create the Auto Scaling group using the launch template, or add the launch template to an existing Auto Scaling group.

To create an Auto Scaling group using a launch template (console)

1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.

2. On the navigation bar at the top of the screen, select the same Region that you used when you created the launch template.

3. In the navigation pane, choose Auto Scaling Groups, Create Auto Scaling group.

4. Choose Launch Template, select your launch template, and then choose Next Step.

5. Complete the fields for the Auto Scaling group. When you've finished reviewing your configuration settings on the Review page, choose Create Auto Scaling group. For more information, see Creating an Auto Scaling Group Using a Launch Template in the Amazon EC2 Auto Scaling User Guide.

To create an Auto Scaling group using a launch template (AWS CLI)

Use the create-auto-scaling-group AWS CLI command and specify the --launch-template parameter.

To add a launch template to an existing Auto Scaling group (console)

1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.

2. On the navigation bar at the top of the screen, select the same Region that you used when you created the launch template.

3. In the navigation pane, choose Auto Scaling Groups.

4. From the Auto Scaling group list, select an Auto Scaling group, and choose Actions, Edit.

5. On the Details tab, for Launch Template, choose a launch template, and then choose Save.

To add a launch template to an existing Auto Scaling group (AWS CLI)

Use the update-auto-scaling-group AWS CLI command and specify the --launch-template parameter.

Viewing the credit specification of a burstable performance instance

You can view the credit specification (unlimited or standard) of a running or stopped instance.

New console

To view the credit specification of a burstable instance

1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.

2. In the left navigation pane, choose Instances.

3. Select the instance.

4. Choose Details and view the Credit specification field. The value is either unlimited or standard.

Old console

To view the credit specification of a burstable instance

1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.

2. In the left navigation pane, choose Instances.

3. Select the instance.

4. Choose Description and view the T2/T3 Unlimited field.

   • If the value is Enabled, then your instance is configured as unlimited.

   • If the value is Disabled, then your instance is configured as standard.

To describe the credit specification of a burstable performance instance (AWS CLI)

Use the describe-instance-credit-specifications command. If you do not specify one or more instance IDs, all instances with the credit specification of unlimited are returned, as well as instances that were previously configured with the unlimited credit specification. For example, if you resize a T3 instance to an M4 instance, while it is configured as unlimited, Amazon EC2 returns the M4 instance.

aws ec2 describe-instance-credit-specifications --instance-id i-1234567890abcdef0

The following is example output:

{
  "InstanceCreditSpecifications": [
    {
        "InstanceId": "i-1234567890abcdef0",
        "CpuCredits": "unlimited"
    }
  ]
}

Modifying the credit specification of a burstable performance instance

You can switch the credit specification of a running or stopped instance at any time between unlimited and standard.

New console

To modify the credit specification of a burstable performance instance

1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.

2. In the left navigation pane, choose Instances.

3. Select the instance. To modify the credit specification for several instances at one time, select all applicable instances.

4. Choose Actions, Instance settings, Change credit specification. This option is enabled only if you selected a burstable performance instance.

5. To change the credit specification to unlimited, select the check box next to the instance ID. To change the credit specification to standard, clear the check box next to the instance ID.

Old console

To modify the credit specification of a burstable performance instance

1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.

2. In the left navigation pane, choose Instances.

3. Select the instance. To modify the credit specification for several instances at one time, select all applicable instances.

4. Choose Actions, Instance Settings, Change T2/T3 Unlimited. This option is enabled only if you selected a burstable performance instance.

5. The current credit specification appears in parentheses after the instance ID. To change the credit specification to unlimited, choose Enable. To change the credit specification to standard, choose Disable.

To modify the credit specification of a burstable performance instance (AWS CLI)

Use the modify-instance-credit-specification command. Specify the instance and its credit specification using the --instance-credit-specification parameter. Valid credit specifications are unlimited and standard.

aws ec2 modify-instance-credit-specification --region us-east-1 --instance-credit-specification "InstanceId=i-1234567890abcdef0,CpuCredits=unlimited"

The following is example output:

{
  "SuccessfulInstanceCreditSpecifications": [
    {
      "InstanceId": "i- 1234567890abcdef0"
    }
  ],
  "UnsuccessfulInstanceCreditSpecifications": []
}

Setting the default credit specification for the account

You can set the default credit specification at the account level per AWS Region. You specify the default credit specification per instance family (for example, T2 or T3).

If you use the Launch Instance Wizard in the AWS Management Console to launch instances, the value you select for the credit specification overrides the account-level default credit specification. If you use the AWS CLI to launch instances, all new burstable performance instances in the account launch using the default credit option. The credit specification for existing running or stopped instances is not affected.

The modify-default-credit-specification API is an asynchronous operation, which works at an AWS Region level and modifies the credit option for each Availability Zone. All zones in a Region are updated within five minutes. But if instances are launched during this operation, they might not get the new credit option until the zone is updated. To verify whether the update has occurred, you can call get-default-credit-specification and check the default credit specification for updates. For more information, see Viewing the default credit specification.

Consideration

The default credit specification for an instance family can be modified only once in a rolling 5-minute period, and up to four times in a rolling 24-hour period.

To set the default credit specification at the account level (AWS CLI)

Use the modify-default-credit-specification command. Specify the AWS Region, instance family, and the default credit specification using the --cpu-credits parameter. Valid default credit specifications are unlimited and standard.

aws ec2 modify-default-credit-specification --region us-east-1 --instance-family t2 --cpu-credits unlimited

Viewing the default credit specification

You can view the default credit specification of a burstable performance instance family at the account level per AWS Region.

To view the default credit specification at the account level (AWS CLI)

Use the get-default-credit-specification command. Specify the AWS Region and instance family.

aws ec2 get-default-credit-specification --region us-east-1 --instance-family t2