How to modify ‘Deletion on Termination’ flag for EBS volume on running EC2 instance.

When launching an EC2 instance on Amazon Web Services, the EBS volume is set to ‘Delete on Termination’ by default. Most of the time this is fine as you’d often rather make a snapshot of your drive to enable you to boot up multiple copies of the same instance, or if you’re a developer that’s creating and terminating instances regularly it would be a nightmare to have all of these orphaned EBS volumes cluttering up your account.

But what do you do when you have a running instance where the EBS was set to Delete and you’ve changed your mind and want to keep it? The AWS documentation is surprisingly vague about this, mostly talking about setting the flag on launch. So how do you do it for a running instance? And for that matter, how can you tell if you set an existing instance to Delete on Termination? It might have been a while and it’s hard to remember if you ticked that checkbox.

How to check the EBS ‘Delete on Termination’ flag

It’s a little buried. Go to your EC2 management console and click on ‘Instances’. Click on the instance you’re curious about, and then under the ‘Description’ tab, scroll down to ‘Block devices’, and click on the appropriate EBS volume. This will pop up an attribute box which will state the Delete on Termination flag. This seems to be the only place in the whole AWS console to check this information!



How to modify¬†the EBS ‘Delete on Termination’ flag

The only way to do this is by using the AWS CLI, at the current time there’s no way to do this using the web console.

You can do this in one of two ways, either by specifying a JSON attribute file with the modifications you want to apply to the instance, or by doing it in-line with escape characters.

aws ec2 modify-instance-attribute --instance-id i-a3ef245 --block-device-mappings /path/to/file.json

with a .json file in the a format such as:

    "DeviceName": "/dev/sda1",
    "Ebs": {
      "DeleteOnTermination": false

Or without using a .json file inline like this:

aws ec2 modify-instance-attribute --instance-id i-a3ef245 --block-device-mappings "[{\"DeviceName\": \"/dev/sda\",\"Ebs\":{\"DeleteOnTermination\":false}}]"

Note:¬†You will need to configure the AWS cli (command from terminal: ‘aws configure’) either with user credentials with a policy that grants permissions to the appropriate EC2 instance, or run the CLI on an instance which has EC2 Role permissions.

Now hopefully you’ll be able to save that EBS volume after changing your mind about the termination flag!


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