Amazon Lambda script: start all appropriately tagged instances

amazon_lambda_start_tagged.py

## Amazon Lambda script: start all appropriately tagged instances
##
## Runs in Amazon Lambda as Python 2.7 or as Python 3.6.
## Intended to be invoked on a schedule by Amazon Cloud Watch.
## Tag relevant instances with label 'autostart', value 'true'.

## TODO It could be good to add logging to this script

import boto3
region = 'eu-west-1' ## Ireland

def lambda_handler(event, context):
    ## Don't call anything just 'ec2', that's confusing
    ec2_resource = boto3.resource('ec2', region_name=region)
    ec2_client   = boto3.client('ec2', region_name=region)

    filters = [{
            'Name': 'tag:autostart',
            'Values': ['true']
        }
    ]

    to_start = ec2_resource.instances.filter(Filters=filters)

    to_start_ids = [instance.id for instance in to_start]

    ec2_client.start_instances(InstanceIds=to_start_ids)


# May want broad rights from the 'execution role'. I used this JSON, based on
# https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_use_switch-role-ec2.html

#  {
#    "Version": "2012-10-17",
#    "Statement": [
#     {
#      "Effect": "Allow",
#      "Action": [
#        "ec2:*"
#      ],
#      "Resource": "*"
#     }
#  
#    ]
#  }




## (MIT Licence)
##
## Copyright 2018 Max Barraclough
## 
## Permission is hereby granted, free of charge, to any person obtaining a copy
## of this software and associated documentation files (the "Software"), to deal
## in the Software without restriction, including without limitation the rights
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## copies of the Software, and to permit persons to whom the Software is
## furnished to do so, subject to the following conditions:
## 
## The above copyright notice and this permission notice shall be included in
## all copies or substantial portions of the Software.
## 
## THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
## IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
## FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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## THE SOFTWARE.