AWS Lambda function to sync tag name between ebs volumes and the attached instance.

named_ebs_volume.py

import boto3
import json
import sys
import botocore.exceptions

client = boto3.client('ec2')
ec2 = boto3.resource('ec2')

def get_instance_volume_list(client, data={}, filters=[]):
    response = client.describe_volumes(Filters=filters)
    # EBSボリュームが一つもないという状態は仮定していない。
    volumes = response.get(u'Volumes')
    for vol in volumes:
        attachments = vol.get(u'Attachments')
        # インスタンスが紐づいていないボリュームには名づけようがない。
        if attachments == []:
            continue
        instanceid = attachments[0][u'InstanceId']
        volumeid = attachments[0][u'VolumeId']
        tags = vol.get(u'Tags')
        if not tags:# Tagsがそもそもない場合。インスタンスのtag:Nameを名前とする。
            data = set_volumeid(data, instanceid, volumeid)
            data = get_hostname(client, data, instanceid)
            continue
        for tag in tags:# {'Key': u'Name', 'Value': u''}の場合。インスタンスのtag:Nameを名前とする。
            if tag.get(u'Key') == u'Name' and tag.get(u'Value') == u'':
                data = set_volumeid(data, instanceid, volumeid)
                data = get_hostname(client, data, instanceid)
                break
    return data


def set_volumeid(data, instanceid, volumeid):
    data.setdefault(instanceid, []).append({})
    data[instanceid][0].setdefault('volumeid', []).append(volumeid)
    return data


def get_hostname(client, data, instanceid):
    data.setdefault(instanceid, []).append({})
    response = client.describe_instances(
        InstanceIds = [instanceid]
    )
    reservations = response.get(u'Reservations', [{}])[0]
    instances = reservations.get(u'Instances', [{}])[0]
    for tag in instances.get(u'Tags', [{}]):
        if u'Name' in tag[u'Key']:
            data[instanceid][0].setdefault('hostname', []).append(tag[u'Value'])
    return data


def create_ebs_tag(ec2, data={}, result={}, dryrun=True):
    for instanceid, ebsinfo in data.iteritems():
        volumeids = ebsinfo[0]["volumeid"]
        hostname = ebsinfo[0]["hostname"][0]
        for vid in volumeids:
            ebsvolume = ec2.Volume(vid)
            try:
                response = ebsvolume.create_tags(
                    DryRun=dryrun,
                    Tags=[{
                        'Key': 'Name',
                        'Value': '{}'.format(hostname)
                    }]
                )
                result.setdefault(vid, []).append(response)
            except botocore.exceptions.ClientError as e:
                if e.response['Error'].get('Code') != 'DryRunOperation':
                    print "failure"
    return result


def lambda_handler(event, context):
    filters = [{'Name': 'status','Values': ['in-use']}]
    volume_data = get_instance_volume_list(client, filters)
    result = create_ebs_tag(ec2, volume_data)
    return json.dumps(dict(get_intance_volume_list=volume_data, create_ebs_tag=str(result)))