https://stackoverflow.com/questions/40040985/how-to-find-instances-that-dont-have-a-tag-using-boto3

 import boto3

client=boto3.client('ec2')

def lambda_handler(event, context):

    instances = [i for i in boto3.resource('ec2', region_name='ap-south-1').instances.all()]

    # Print instance_id of instances that do not have a Tag of Key='Foo'

    for i in instances:

        if i.tags is not None and 'resource' not in [t['Key'] for t in i.tags]:

            print (i.instance_id)

            ids=[]

            ids.append(i.instance_id)

            print (ids)

            client.stop_instances(InstanceIds=ids)

       #     client.stop_instances(i.instance_id)

 

    #ec2= boto3.resource('ec2', region_name = 'ap-south-1')

    #for each in ec2.instances.all():

     #   print (each.id)