How to set EBS root volume to persist for an EC2 instance within Elastic Beanstalk using Terraform

Question

I have written Terraform to manage my AWS Elastic Beanstalk environment and application, using the default docker solution stack for my region.

The EC2 instance created by autoscaling has the standard/default EBS root volume which is set to "true" value for the setting "DeleteOnTermination" -- meaning that when the instance is replaced or destroyed, the volume (and hence all the data) is also destroyed.

I would like to change this to false and persist the volume.

For some reason, I cannot find valid Terraform documentation for how to change this setting so that the root volume persists. The closest thing I can find is for the autoscaling launchconfiguration, a "root_block_device" mapping can be supplied to update it. Unfortunately, it is unclear from the documentation how exactly to use this. If I create a launchconfiguration resource, how do I use that within my beanstalk definition. I think I'm on the right track here but need some guidance.

Do I create the autoscaling resource and then reference it within my beanstalk definition? Or do I add a particular setting to my beanstalk definition with this mapping inside? Thanks for any help or example you can provide.

Marcin Marcin · Accepted Answer · 2020-07-21T22:56:31

This can done at EB level through Resources.

Specifically, you have to modify settings of AWSEBAutoScalingLaunchConfiguration that EB is using to launch your instances from.

Here is an example of such a config file:

.ebextensions/40_ebs_delete_on_termination.config

Resources:

  AWSEBAutoScalingLaunchConfiguration:
    Type: AWS::AutoScaling::LaunchConfiguration
    Properties:
      BlockDeviceMappings:
        - DeviceName: /dev/xvda
          Ebs:
            DeleteOnTermination: false

Then to verify the setting, you can use AWS CLI:

aws ec2 describe-volumes --volume-ids <id-of-your-eb-instance-volume>

or simply terminate the environment and check the Volumes in EC2 console.

How to set EBS root volume to persist for an EC2 instance within Elastic Beanstalk using Terraform

2 Answers