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I know that the command ec2-create-image instance-id will be creating an image of the ec2 instance, creating snapshots file and registering as an AMI. But what is the equivalent command to delete the image which will deleting associated snapshot files and de-registering AMI?

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There are typically 4 steps to what you are looking for:

  1. Terminate instances using the AMI (recommend practise especially for S3 backed AMIs) [Not required before deleting an AMI of any type]
  2. Deregister AMIs using ec2-deregister
  3. Delete the bundles/snapshots backing the AMI using ec2-delete-bundle (for S3) or ec2-delete-snapshot (for EBS).
  4. Delete EBS volumes (unless they are set to delete on termination, in which case, they would be removed in step #1). This isn't necessary for S3 backed instances. [Again, it is not necessary to terminate instances or delete volumes if you just want to delete an AMI.]

Keep in mind that snapshots and images are independent. You can create an EBS volume from a snapshot and use it as a secondary drive instead of as a boot drive. Furthermore (in the case of Linux instances) it is possible to create a new image from an existing snapshot - which lends reason to the idea that not everyone who wants to delete an image also wants to delete the associated snapshot(s). (Although you can register a snapshot to create a Windows AMI, the AMI isn't launchable.)

It is worth noting that AWS will not let you delete a snapshot associated with an AMI before you deregister the AMI.

Focussing on steps 2 and 3 above, you first need to find the snapshot ID(s) associated with an AMI. This should be listed as part of the block device mappings. Typically, the root EBS volume has the mount point /dev/sda1. You can deregister the AMI from the command line (or use the AWS console) and then delete the snapshot (again, either from the command line or the AWS console).

If you needed to perform this task more often, you would want to script the process. Some libraries such as Python Boto include a function to do exactly this:

deregister_image(image_id, delete_snapshot=False)
    Unregister an AMI.

    Parameters: 
        image_id (string) – the ID of the Image to unregister
        delete_snapshot (bool) – Set to True if we should delete the snapshot associated with an EBS volume mounted at /dev/sda1

For instance a sample script (completely untested, and just cobbled together - use at your own risk!) based on the above might look like :

#!/usr/bin/env python

import os
import sys

def ec2delete(imageid=None):
    conn = boto.ec2.connect_to_region('your_region', aws_access_key_id='your_key', aws_secret_access_key='your_secret') 
    conn.deregister_image(imageid, delete_snapshot=True)

if __name__ == '__main__':
    from optparse import OptionParser
    parser = OptionParser()

    options, args = parser.parse_args()
    sys.stderr.write("Deleting %s and snapshots\n" %  str(args))
    ec2delete(args)
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1  
There is no need to terminate instances of an AMI before deleting the AMI. The AMI is only used to start the instances and they can continue functioning just fine without it. However, if you delete the AMI and the instances fail, then it may be difficult to start replacement instances without the AMI, so be careful. – Eric Hammond Oct 10 '12 at 8:29
1  
AWS used to recommend terminating instances for a 'complete cleanup', however, in principle it should not be needed for deleting an AMI. I do wonder if it might matter in some edge cases though, since EBS volumes load 'lazily', if a snapshot is deleted shortly after an instance is launched, but before the EBS volume has fully loaded, it could be problematic. – cyberx86 Oct 10 '12 at 11:23
    
@cyberx86: If a snapshot deletion affected a new volume creation, it would be a bigger problem than just for deleting AMIs. Given how long it takes to populate a volume fully from a snapshot, it should be easy to test with a snapshot full of data. – Eric Hammond Oct 11 '12 at 2:12
2  
@EricHammond: a quick search shows that AWS will apparently not delete the snapshot until the data has loaded, but will still let you perform the deletion (presumably simply holding on to the snapshot until it is not needed). – cyberx86 Oct 11 '12 at 2:24
    
@cyberx86: As I suspected, but nice to know for sure. Thanks for looking it up. – Eric Hammond Oct 13 '12 at 18:07

Note that old answer that got downvoted was removed since it became out of sync with the new AWS web GUI.

If you are using python3 and have the correct credentials file setup in your root directory you can do this:

import boto3
from botocore.client import ClientError


def deregister_image(image_id=''):
    try:
        ec2resource = boto3.resource('ec2')
        image = ec2resource.Image(image_id)
        print(image.block_device_mappings)
        snapshot_id = image.block_device_mappings[0]['Ebs']['SnapshotId']
        # Deregister Image
        response = image.deregister()             
        print('Image', image_id, 'deregistered.')
        return snapshot_id
    except ClientError:
        print('Image', image_id, 'does not exist, and cannot be deregistered.')


def delete_snapshot(snapshot_id=''):
    try:
        ec2resource = boto3.resource('ec2')
        snapshot = ec2resource.Snapshot(snapshot_id)
        # Delete EBS snapshot.
        response = snapshot.delete()               
        print('Snapshot', snapshot_id, 'deleted.')
    except ClientError:
        print('Snapshot', snapshot_id, 'does not exist, and cannot be deleted.')

# deregister image and delete associated snapshot
image_id = 'ami-XXXXXX'
snapshot_id = deregister_image(image_id=image_id)
delete_snapshot(snapshot_id=snapshot_id)
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If you are going to downvote then explain why. – nu everest Feb 29 at 21:08

Updated answer from the aws docs:

  1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
  2. In the navigation bar, verify your region.
  3. In the navigation panel, click AMIs.
  4. Select the AMI, click Actions, and then click Deregister. When prompted for confirmation, click Continue.
  5. In the navigation pane, click Snapshots.
  6. Select the snapshot, click Actions, and then click Delete. When prompted for confirmation, click Yes, Delete.

Hope this help anyone like me! :D

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