Automatically tag EC2 snapshots and volumes based on their attached AMIs/instances

tag-vols-snaps.py

# most credit to the original: https://gist.github.com/brandond/6b4d22eaefbd66895f230f68f27ee586

# Tag snapshots based on their associated AMI and volumes based on attached instance.
# format:
#    (AMI:db5|db5) /dev/sda1 (1/4)
#    (AMI:db5|db5) /dev/sdb (2/4)

# Best practice: create IAM user
# Simplest privilege to get it to work with reasonable security:  use predefined policy "ReadOnlyAccess" 
# and add your own custom policy that grants  "ec2:CreateTags" 


import copy
import logging
import os
import boto3

logging.basicConfig(level=os.environ.get('LOG_LEVEL', 'INFO'))

ec2 = boto3.client('ec2')
logger = logging.getLogger(__name__)

def tag_snapshots():
    snapshots = {}

    for response in ec2.get_paginator('describe_snapshots').paginate(OwnerIds=['self']):
        snapshots.update([(snapshot['SnapshotId'], snapshot) for snapshot in response['Snapshots']])

    for image in ec2.describe_images(Owners=['self'])['Images']:
        tags = boto3_tag_list_to_ansible_dict(image.get('Tags', []))
        # to tag volumes, e.g., (1/3) (2/3) (3/3)
        devnum = 0
        numberofdevs=len(image['BlockDeviceMappings'])
        for device in image['BlockDeviceMappings']:
            if 'SnapshotId' in device['Ebs']:
                devnum += 1
                snapshot = snapshots[device['Ebs']['SnapshotId']]
                snapshot['Used'] = True
                cur_tags = boto3_tag_list_to_ansible_dict(snapshot.get('Tags', []))
                new_tags = copy.deepcopy(cur_tags)
                new_tags.update(tags)
                new_tags['ImageId'] = image['ImageId']
                # here's where to change formatting
                new_tags['Name'] = 'AMI:' + image['Name'] + ' ' + device['DeviceName'] + ' (' + str(devnum) + '/' + str(numberofdevs) + ')'
                if new_tags != cur_tags:
                    logger.info('{0}: Tags changed to {1}'.format(snapshot['SnapshotId'], new_tags))
                    ec2.create_tags(Resources=[snapshot['SnapshotId']], Tags=ansible_dict_to_boto3_tag_list(new_tags))

    for snapshot in snapshots.values():
        if 'Used' not in snapshot:
            cur_tags = boto3_tag_list_to_ansible_dict(snapshot.get('Tags', []))
            name = cur_tags.get('Name', snapshot['SnapshotId'])
            if not name.startswith('UNUSED'):
                logger.warning('{0} Unused!'.format(snapshot['SnapshotId']))
                cur_tags['Name'] = 'UNUSED ' + name
                ec2.create_tags(Resources=[snapshot['SnapshotId']], Tags=ansible_dict_to_boto3_tag_list(cur_tags))


def tag_volumes():
    volumes = {}
    for response in ec2.get_paginator('describe_volumes').paginate():
        volumes.update([(volume['VolumeId'], volume) for volume in response['Volumes']])

    for response in ec2.get_paginator('describe_instances').paginate():
        for reservation in response['Reservations']:
            for instance in reservation['Instances']:
                tags = boto3_tag_list_to_ansible_dict(instance.get('Tags', []))
                # to tag the number volumes on an instance, e.g., (1/3) (2/3) (3/3)
                devnum = 0
                numberofdevs=len(instance['BlockDeviceMappings'])
                for device in instance['BlockDeviceMappings']:
                    devnum += 1
                    volume = volumes[device['Ebs']['VolumeId']]
                    volume['Used'] = True
                    cur_tags = boto3_tag_list_to_ansible_dict(volume.get('Tags', []))
                    new_tags = copy.deepcopy(cur_tags)
                    new_tags.update(tags)
                    # here's where to change formatting
                    new_tags['Name'] = tags['Name'] + ' ' + device['DeviceName'] + ' (' + str(devnum) + '/' + str(numberofdevs) + ')'
                    if new_tags != cur_tags:
                        logger.info('{0} Tags changed to {1}'.format(volume['VolumeId'], new_tags))
                        ec2.create_tags(Resources=[volume['VolumeId']], Tags=ansible_dict_to_boto3_tag_list(new_tags))

    for volume in volumes.values():
        if 'Used' not in volume:
            cur_tags = boto3_tag_list_to_ansible_dict(volume.get('Tags', []))
            name = cur_tags.get('Name', volume['VolumeId'])
            if not name.startswith('UNUSED'):
                logger.warning('{0} Unused!'.format(volume['VolumeId']))
                cur_tags['Name'] = 'UNUSED ' + name
                ec2.create_tags(Resources=[volume['VolumeId']], Tags=ansible_dict_to_boto3_tag_list(cur_tags))


def tag_everything():
    tag_snapshots()
    tag_volumes()


def boto3_tag_list_to_ansible_dict(tags_list):
    tags_dict = {}
    for tag in tags_list:
        if 'key' in tag and not tag['key'].startswith('aws:'):
            tags_dict[tag['key']] = tag['value']
        elif 'Key' in tag and not tag['Key'].startswith('aws:'):
            tags_dict[tag['Key']] = tag['Value']

    return tags_dict

def ansible_dict_to_boto3_tag_list(tags_dict):
    tags_list = []
    for k, v in tags_dict.items():
        tags_list.append({'Key': k, 'Value': v})

    return tags_list


def handler(event, context):
    tag_everything()


if __name__ == '__main__':
    tag_everything()