Examples for working with Elastic Load Balancing with the AWS Command Line Interface (AWS CLI) - Amazon EC2 Auto Scaling

Examples for working with Elastic Load Balancing with the AWS Command Line Interface (AWS CLI)

Use the AWS CLI to attach, detach, and describe load balancers and target groups, add and remove Elastic Load Balancing health checks, and change which Availability Zones are enabled.

This topic shows examples of AWS CLI commands that perform common tasks for Amazon EC2 Auto Scaling.

Important

For additional command examples, see aws elbv2 and aws elb in the AWS CLI Command Reference.

Attach your target group or Classic Load Balancer

Use the following create-auto-scaling-group command to create an Auto Scaling group and simultaneously attach a target group by specifying its Amazon Resource Name (ARN). The target group can be associated with an Application Load Balancer, a Network Load Balancer, or a Gateway Load Balancer.

Replace the sample values for --auto-scaling-group-name, --vpc-zone-identifier, --min-size, and --max-size. For the --launch-template option, replace my-launch-template and 1 with the name and version of a launch template for your Auto Scaling group. For the --traffic-sources option, replace the sample ARN with the ARN of a target group for an Application Load Balancer, Network Load Balancer, or Gateway Load Balancer.

aws autoscaling create-auto-scaling-group --auto-scaling-group-name my-asg \ --launch-template LaunchTemplateName=my-launch-template,Version='1' \ --vpc-zone-identifier "subnet-5ea0c127,subnet-6194ea3b,subnet-c934b782" \ --min-size 1 --max-size 5 \ --traffic-sources "Identifier=arn:aws:elasticloadbalancing:region:account-id:targetgroup/my-targets/12345678EXAMPLE1"

Use the attach-traffic-sources command to attach additional target groups to the Auto Scaling group after it's created.

The following command adds another target group to the same group.

aws autoscaling attach-traffic-sources --auto-scaling-group-name my-asg \ --traffic-sources "Identifier=arn:aws:elasticloadbalancing:region:account-id:targetgroup/my-targets/12345678EXAMPLE2"

Alternatively, to attach a Classic Load Balancer to your group, specify the --traffic-sources and --type options when you use create-auto-scaling-group or attach-traffic-sources, as in the following example. Replace my-classic-load-balancer with the name of a Classic Load Balancer. For the --type option, specify a value of elb.

--traffic-sources "Identifier=my-classic-load-balancer" --type elb

Describe your target groups or Classic Load Balancers

To describe the load balancers or target groups attached to your Auto Scaling group, use the following describe-traffic-sources command. Replace my-asg with the name of your group.

aws autoscaling describe-traffic-sources --auto-scaling-group-name my-asg

The example returns the ARN of the Elastic Load Balancing target groups that you attached to the Auto Scaling group.

{ "TrafficSources": [ { "Identifier": "arn:aws:elasticloadbalancing:region:account-id:targetgroup/my-targets/12345678EXAMPLE1", "State": "InService", "Type": "elbv2" }, { "Identifier": "arn:aws:elasticloadbalancing:region:account-id:targetgroup/my-targets/12345678EXAMPLE2", "State": "InService", "Type": "elbv2" } ] }

For an explanation of the State field in the output, see Verify the attachment status of your load balancer.

Add Elastic Load Balancing health checks

To add Elastic Load Balancing health checks to the health checks that your Auto Scaling group performs on instances, use the following update-auto-scaling-group command and specify ELB as the value for the --health-check-type option. Replace my-asg with the name of your group.

aws autoscaling update-auto-scaling-group --auto-scaling-group-name my-asg \ --health-check-type "ELB"

New instances often need time for a brief warm-up before they can pass a health check. If the grace period doesn't provide enough warm-up time, the instances might not appear ready to serve traffic. Amazon EC2 Auto Scaling might consider those instances unhealthy and replace them.

To update the health check grace period, use the --health-check-grace-period option when you use update-auto-scaling-group, as in the following example. Replace 300 with the number of seconds to keep new instances in service before terminating them if they're found to be unhealthy.

--health-check-grace-period 300

For more information, see Health checks for instances in an Auto Scaling group.

Change your Availability Zones

Changing your Availability Zones has some limitations that you should be aware of. For more information, see Limitations.

To change the Availability Zones for an Application Load Balancer or Network Load Balancer
  1. Before you change the Availability Zones of the load balancer, it's a good idea to first update the Availability Zones of the Auto Scaling group to verify that there is availability for your instance types in the specified zones.

    To update the Availability Zones for your Auto Scaling group, use the following update-auto-scaling-group command. Replace the sample subnet IDs with the IDs of the subnets in the Availability Zones to enable. The specified subnets replace the previously enabled subnets. Replace my-asg with the name of your group.

    aws autoscaling update-auto-scaling-group --auto-scaling-group-name my-asg \ --vpc-zone-identifier "subnet-41767929,subnet-cb663da2,subnet-8360a9e7"
  2. Use the following describe-auto-scaling-groups command to verify that the instances in the new subnets have launched. If the instances have launched, you see a list of the instances and their statuses. Replace my-asg with the name of your group.

    aws autoscaling describe-auto-scaling-groups --auto-scaling-group-name my-asg
  3. Use the following set-subnets command to specify the subnets for your load balancer. Replace the sample subnet IDs with the IDs of the subnets in the Availability Zones to enable. You can specify only one subnet per Availability Zone. The specified subnets replace the previously enabled subnets. Replace my-lb-arn with the ARN of your load balancer.

    aws elbv2 set-subnets --load-balancer-arn my-lb-arn \ --subnets subnet-41767929 subnet-cb663da2 subnet-8360a9e7
To change the Availability Zones for a Classic Load Balancer
  1. Before you change the Availability Zones of the load balancer, it's a good idea to first update the Availability Zones of the Auto Scaling group to verify that there is availability for your instance types in the specified zones.

    To update the Availability Zones for your Auto Scaling group, use the following update-auto-scaling-group command. Replace the sample subnet IDs with the IDs of the subnets in the Availability Zones to enable. The specified subnets replace the previously enabled subnets. Replace my-asg with the name of your group.

    aws autoscaling update-auto-scaling-group --auto-scaling-group-name my-asg \ --vpc-zone-identifier "subnet-41767929,subnet-cb663da2"
  2. Use the following describe-auto-scaling-groups command to verify that the instances in the new subnets have launched. If the instances have launched, you see a list of the instances and their statuses. Replace my-asg with the name of your group.

    aws autoscaling describe-auto-scaling-groups --auto-scaling-group-name my-asg
  3. Use the following attach-load-balancer-to-subnets command to enable a new Availability Zone for your Classic Load Balancer. Replace the sample subnet ID with the ID of the subnet for the Availability Zone to enable. Replace my-lb with the name of your load balancer.

    aws elb attach-load-balancer-to-subnets --load-balancer-name my-lb \ --subnets subnet-cb663da2

    To disable an Availability Zone, use the following detach-load-balancer-from-subnets command. Replace the sample subnet ID with the ID of the subnet for the Availability Zone to disable. Replace my-lb with the name of your load balancer.

    aws elb detach-load-balancer-from-subnets --load-balancer-name my-lb \ --subnets subnet-8360a9e7

Detach your target group or Classic Load Balancer

The following detach-traffic-sources command detaches a target group from your Auto Scaling group when you no longer need it.

For the --auto-scaling-group-name option, replace my-asg with the name of your group. For the --traffic-sources option, replace the sample ARN with the ARN of a target group for an Application Load Balancer, Network Load Balancer, or Gateway Load Balancer.

aws autoscaling detach-traffic-sources --auto-scaling-group-name my-asg \ --traffic-sources "Identifier=arn:aws:elasticloadbalancing:region:account-id:targetgroup/my-targets/1234567890123456"

To detach a Classic Load Balancer from your group, specify the --traffic-sources and --type options, as in the following example. Replace my-classic-load-balancer with the name of a Classic Load Balancer. For the --type option, specify a value of elb.

--traffic-sources "Identifier=my-classic-load-balancer" --type elb

Remove Elastic Load Balancing health checks

To remove Elastic Load Balancing health checks from your Auto Scaling group, use the following update-auto-scaling-group command and specify EC2 as the value for the --health-check-type option. Replace my-asg with the name of your group.

aws autoscaling update-auto-scaling-group --auto-scaling-group-name my-asg \ --health-check-type "EC2"

For more information, see Health checks for instances in an Auto Scaling group.

Legacy commands

The following examples show how you can use legacy CLI commands to attach, detach, and describe load balancers and target groups. They remain in this document as a reference for any customers who want to use them. We continue to support the legacy CLI commands, but we recommend that you use the new "traffic sources" CLI commands, which can attach and detach multiple traffic sources types. You can use both the legacy CLI commands and the "traffic sources" CLI commands on the same Auto Scaling group.

To attach your target group

The following create-auto-scaling-group command creates an Auto Scaling group with an attached target group. Specify the Amazon Resource Name (ARN) of a target group for an Application Load Balancer, Network Load Balancer, or Gateway Load Balancer.

aws autoscaling create-auto-scaling-group --auto-scaling-group-name my-asg \ --launch-template LaunchTemplateName=my-launch-template,Version='1' \ --vpc-zone-identifier "subnet-5ea0c127,subnet-6194ea3b,subnet-c934b782" \ --target-group-arns "arn:aws:elasticloadbalancing:region:account-id:targetgroup/my-targets/1234567890123456" \ --min-size 1 --max-size 5

The following attach-load-balancer-target-groups command attaches a target group to an existing Auto Scaling group.

aws autoscaling attach-load-balancer-target-groups --auto-scaling-group-name my-asg \ --target-group-arns "arn:aws:elasticloadbalancing:region:account-id:targetgroup/my-targets/1234567890123456"
To attach your Classic Load Balancer

The following create-auto-scaling-group command creates an Auto Scaling group with an attached Classic Load Balancer.

aws autoscaling create-auto-scaling-group --auto-scaling-group-name my-asg \ --launch-configuration-name my-launch-config \ --vpc-zone-identifier "subnet-5ea0c127,subnet-6194ea3b,subnet-c934b782" \ --load-balancer-names "my-load-balancer" \ --min-size 1 --max-size 5

The following attach-load-balancers command attaches the specified Classic Load Balancer to an existing Auto Scaling group.

aws autoscaling attach-load-balancers --auto-scaling-group-name my-asg \ --load-balancer-names my-lb
To describe target groups

To describe the target groups associated with an Auto Scaling group, use the describe-load-balancer-target-groups command. The following example lists the target groups for my-asg.

aws autoscaling describe-load-balancer-target-groups --auto-scaling-group-name my-asg
To describe Classic Load Balancers

To describe the Classic Load Balancers associated with an Auto Scaling group, use the describe-load-balancers command. The following example lists the Classic Load Balancers for my-asg.

aws autoscaling describe-load-balancers --auto-scaling-group-name my-asg
To detach a target group

The following detach-load-balancer-target-groups command detaches a target group from your Auto Scaling group when you no longer need it.

aws autoscaling detach-load-balancer-target-groups --auto-scaling-group-name my-asg \ --target-group-arns "arn:aws:elasticloadbalancing:region:account-id:targetgroup/my-targets/1234567890123456"
To detach a Classic Load Balancer

The following detach-load-balancers command detaches a Classic Load Balancer from your Auto Scaling group when you no longer need it.

aws autoscaling detach-load-balancers --auto-scaling-group-name my-asg \ --load-balancer-names my-lb