list-unused-reserved-ec2-instances.py

import boto3
import sys

ec2 = boto3.client('ec2')
instances_list = []
instancetype_with_count = ()
current_instances = ec2.describe_instances()
count = 0

# Fetching all reserved instances that are active
rinstances_list = ec2.describe_reserved_instances(
    Filters=[
        {
            'Name': 'state',
            'Values': [
                'active',
            ]
        },
    ]
)

# Fetch Purchases by Instance Type and Platform
for instances in rinstances_list['ReservedInstances']:
    instancetype_with_count = (
    instances['ProductDescription'] + "-" + instances['InstanceType'], instances['InstanceCount'])
    instances_list.append(instancetype_with_count)

# Add Just to ensure multiple purchases of same instance type and platform exists in our case so getting unique count.
instances_dict = {}
for instance in instances_list:
    # print(instance)
    if instance[0] in instances_dict:
        instances_dict[instance[0]] += instance[1]
    else:
        instances_dict[instance[0]] = instance[1]

# print(instances_dict)

print("Current Active Reserved Instances:" + str(instances_list))

for rinst_dict in instances_dict:

    rinstance_platform = rinst_dict.split('-', 1)[0]
    rinstance_itype = rinst_dict.split('-', 1)[1]
    for reservation in current_instances['Reservations']:
        for instance in reservation['Instances']:
            if rinstance_platform == "Linux/UNIX":
                if instance['InstanceType'] == rinstance_itype and instance['State']['Name'] == "running":
                    count = count + 1
            else:
                if 'Platform' in instance.keys():
                    if instance['InstanceType'] == rinstance_itype and instance['State']['Name'] == "running" and \
                            instance['Platform'] == "windows":
                        count = count + 1

    if count < instances_dict[rinst_dict]:
        print("For " + rinstance_itype + "(" + rinstance_platform + ") Expected Count: " + str(
            instances_dict[rinst_dict]) + " Current Count: " + str(count))
    count = 0