gistfile1.txt

#!/usr/bin/env python

import argparse
import boto3
import sys
import urllib.request
import subprocess

from glob import glob
from os.path import basename, dirname

def physical_drives():
    drive_glob = '/sys/block/*/device'
    return [basename(dirname(d)) for d in glob(drive_glob)]

def main():
    ap = argparse.ArgumentParser(description="EBS attach and mount CLI")
    vg = ap.add_mutually_exclusive_group(required=True)
    vg.add_argument(
            "-i",
            "--volume-id",
            help="volume id of the EBS volume to attach (required if volume name not specified)",
    )
    vg.add_argument(
            "-n",
            "--volume-name",
            help="volume name of the EBS volume to attach (required if volume id not specified)",
    )
    ap.add_argument(
            "-d",
            "--device-id",
            required=True,
            help="device id to use when attaching EBS volume to instance (i.e. /dev/sdf)",
    )
    ap.add_argument(
            "-m",
            "--mount-dir",
            required=True,
            help="absolute path to directory where the newly attached volume will be mounted (i.e. /data)",
    )

    args = ap.parse_args()

    ec2 = boto3.client('ec2')

    # set volume_id
    if args.volume_id is None:
        resp = ec2.describe_volumes(
                Filters=[
                    {
                        'Name': 'tag:Name',
                        'Values': [args.volume_name]
                    }
                ],
        )
        if len(resp['Volumes']) == 0:
            print("No volumes found with Name: %s" % args.volume_name)
            exit(-1)
        elif len(resp['Volumes']) > 1:
            print("Found more than 1 volume with the Name: %s" % args.volume_name)
            exit(-1)
        else:
            args.volume_id = resp['Volumes'][0]['VolumeId']

    pre_attach_drives = physical_drives()

    # attach volume to instance
    req = urllib.request.Request('http://169.254.169.254/latest/meta-data/instance-id')
    with urllib.reqeust.urlopen(req) as res:
        instance_id = res.read()

    ec2.attach_volume(
            VolumeId=args.volume_id,
            InstanceId=instance_id,
            Device=args.device_id,
    )

    ec2.get_waiter('volume_in_use').wait(
            Filters=[
                {
                    'Name': 'attachment.status',
                    'Values': ['attached'],
                },
            ],
            VolumeIds=[args.volume_id],
    )

    post_attach_drives = physical_drives()

    # set local_device_id by diff of pre/post attach device list
    new_device_list = list(set(pre_attach_drives).symmetric_difference(set(post_attach_drives)))
    if len(new_device_list) != 1:
        print("Error: %d new devices found, was expecting 1." % len(new_device_list))
        exit(-1)

    local_device_id = "/dev/" + new_device_list[0]

    # mount using /usr/local/bin/mkfs-mount-ebs
    p = subprocess.Popen(["mkfs-mount-ebs", local_device_id, args.mount_dir, "ext4"], stdout=subprocess.PIPE)
    p.wait()

if __name__ == '__main__':
    main()