README: volume-attacher - attaches EBS volumes to instances, switching and deleting old ones if needed

License: You can use/modify/circulate or do whatever you want.
         Just note that this script is given "As Is" without any warranty


Requirements:

    Needs python 2.7.3 or newer (not python 3)
    boto library (at least 2.24.0). Can be dowmloaded here:
        https://pypi.python.org/pypi/boto/#downloads

usage: volume-attacher.py [-h] --instance INSTANCE --volume VOLUME --device
                          DEVICE [--region REGION] [--access_key ACCESS_KEY]
                          [--secret_key SECRET_KEY] [--force]
                          {attach,switch,switchanddelete}

Attaches EBS voluems to instances + switches with existing volumes.

positional arguments:
  {attach,switch,switchanddelete}

optional arguments:
  -h, --help            show this help message and exit
  --instance INSTANCE   EC2 instance ID to perform the action on
  --volume VOLUME       EBS volume ID to attach
  --device DEVICE       device to use when attaching the volume to the
                        instance
  --region REGION       AWS region the instance is in. If missing default is
                        used
  --access_key ACCESS_KEY
                        AWS API access key. If missing default is used
  --secret_key SECRET_KEY
                        AWS API secret key. If missing default is used
  --force               If set, this flag will prevent confirmation for the
                        action
        

Actions: 
    attach - simply attaches an EBS volume to an instance, using specified device
    switch - will stop the instance, detach any volume that is attached to specicied device, 
             attaches the new volume instead, and starts the instance
    switchanddelete - will stop the instance, detach any volume that is attached to specicied device, 
             deletes the old volume, attaches the new volume instead, and starts the instance
           
Defaults:

    At the top of the script there are 3 default definitions:
    AWS_ACCESS_KEY - default access key. If the scripts runs on an instance with a sufficient
                 IAM role, it can be left as None and will work. If not can be switched to
                 AWS_ACCESS_KEY = 'AKIAIVXXXXXXN3G3N32Q'
    AWS_SECRET_KEY - default secret key. If the scripts runs on an instance with a sufficient
                 IAM role, it can be left as None and will work. If not can be switched to
                 AWS_ACCESS_KEY = 'UGSYQL6PXXXXXXXXXX0Bf0bS/S+OwnA2GrJ0MOY4Y'
                 
    AWS_REGION - defualt region in case --region is dropped. example:
                 AWS_REGION = u'us-east-1'   
    
           
Examples:
    python volume-attacher.py --access_key AKIAIVKXXXXXXXG3N32Q --secret_key UGSYQL6XXXXXXXXXXXX0bS/S+OwnA2GrJ0MOY4Y 
                              --volume vol-dxx2129c --instance i-16xx3f38 --device /dev/sdb --force switch
        
    python volume-attacher.py --access_key AKIAIVKXXXXXXXG3N32Q --secret_key UGSYQL6XXXXXXXXXXXX0bS/S+OwnA2GrJ0MOY4Y 
                              --volume vol-dxx2129c --instance i-16xx3f38 --device /dev/sdb switchanddelete