Work with Lambda timers and EC2 instances

README.md

Lambda + EC2

You can describe instances using the CLI:

aws ec2 desribe-instances

and with jq you can deserialize the JSON in your terminal. For instance if you wanted a list of all your InstanceIds:

aws ec2 describe-instances | jq -r '.Reservations.[].Instances.[].InstanceId'

With boto3 you can do the same, and filtering becomes simpler and more Pythonic:

import boto3

ec2 = boto3.client('ec2')
response = ec2.describe_instances()
print(response)

describe-instances.py

import boto3

ec2 = boto3.client('ec2')

response = ec2.describe_instances(
#    Filters=[
#        {'Name': 'tag:business_hours_only', 'Values': ['True']},
#        {'Name': 'instance-state-name', 'Values': ['running', 'stopped']}
#    ]
)

instance_ids = [
    instance['InstanceId']
    for reservation in response['Reservations']
    for instance in reservation['Instances']
]

print(instance_ids)

iam-policy.json

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "CloudWatchLogs",
      "Effect": "Allow",
      "Action": [
        "logs:CreateLogGroup",
        "logs:CreateLogStream",
        "logs:PutLogEvents"
      ],
      "Resource": "arn:aws:logs:*:*:*"
    },
    {
      "Sid": "EC2Describe",
      "Effect": "Allow",
      "Action": [
        "ec2:DescribeInstances",
        "ec2:DescribeInstanceStatus"
      ],
      "Resource": "*"
    },
    {
      "Sid": "EC2StartStop",
      "Effect": "Allow",
      "Action": [
        "ec2:StartInstances",
        "ec2:StopInstances"
      ],
      "Resource": "arn:aws:ec2:*:*:instance/*"
    }
  ]
}