Configuration changes - AWS Elastic Beanstalk

Configuration changes

When you modify configuration option settings in the Configuration section of the environment management console, AWS Elastic Beanstalk propagates the change to all affected resources. These resources include the load balancer that distributes traffic to the Amazon EC2 instances running your application, the Auto Scaling group that manages those instances, and the EC2 instances themselves.

Many configuration changes can be applied to a running environment without replacing existing instances. For example, setting a health check URL triggers an environment update to modify the load balancer settings, but doesn't cause any downtime because the instances running your application continue serving requests while the update is propagated.

Configuration changes that modify the launch configuration or VPC settings require terminating all instances in your environment and replacing them. For example, when you change the instance type or SSH key setting for your environment, the EC2 instances must be terminated and replaced. Elastic Beanstalk provides several policies that determine how this replacement is done.

  • Rolling updates – Elastic Beanstalk applies your configuration changes in batches, keeping a minimum number of instances running and serving traffic at all times. This approach prevents downtime during the update process. For details, see Rolling updates.

  • Immutable updates – Elastic Beanstalk launches a temporary Auto Scaling group outside of your environment with a separate set of instances running with the new configuration. Then Elastic Beanstalk places these instances behind your environment's load balancer. Old and new instances both serve traffic until the new instances pass health checks. At that time, Elastic Beanstalk moves the new instances into your environment's Auto Scaling group and terminates the temporary group and old instances. For details, see Immutable updates.

  • Disabled – Elastic Beanstalk makes no attempt to avoid downtime. It terminates your environment's existing instances and replaces them with new instances running with the new configuration.

Warning

Some policies replace all instances during the deployment or update. This causes all accumulated Amazon EC2 burst balances to be lost. It happens in the following cases:

  • Managed platform updates with instance replacement enabled

  • Immutable updates

  • Deployments with immutable updates or traffic splitting enabled

Supported update types
Rolling update setting Load balanced environments Single-instance environments Legacy Windows server environments†

Disabled

Yes

Yes

Yes

Rolling Based on Health

Yes

No

Yes

Rolling Based on Time

Yes

No

Yes

Immutable

Yes

Yes

No

† For the purpose of this table, a Legacy Windows Server Environment is an environment based on a Windows Server platform configuration that use an IIS version earlier than IIS 8.5.