datetime.datetime object is not subscriptable - json

Question

I am trying to get the volume create time for all of my EC2 instances. The problem is the boto3 response returns CreateTime as a datetime object, which is not subscriptable. I try to use the strftime() to convert the object to type str but I must be using the wrong syntax or something because I am stil gtting the error. Below is my code and the traceback:
CODE:
import boto3
import json
import os
import csv
from datetime import datetime, date, time
ec2 = boto3.client('ec2')
ec2_response = ec2.describe_instances(Filters=[{'Name': 'instance-state-name', 'Values': ['running']}])
for item in ec2_response['Reservations']:
instance_id = item['Instances'][0]['InstanceId']
image_id = item['Instances'][0]['ImageId']
create_time = item['Instances'][0]['BlockDeviceMappings'][0]['Ebs']['AttachTime'].strftime("%A, %d. %B %Y %I:%M%p")
print(instance_id,image_id,create_time)
Traceback:
create_time = item['Instances'][0]['BlockDeviceMappings'][0]['Ebs']['AttachTime'][0].strftime("%A, %d. %B %Y %I:%M%p")
TypeError: 'datetime.datetime' object is not subscriptable

Answer 1

Firstly,
item['Instances'][0]['BlockDeviceMappings'][0]['Ebs']['AttachTime']
should not be a list. It's an item in the documentation here and it's also an item in the JSON returned by the following aws cli command:
aws --region us-east-1 ec2 describe-instances
I suspect that when you remove the last [0] from
item['Instances'][0]['BlockDeviceMappings'][0]['Ebs']['AttachTime'][0]
the line of code completes successfully and list index out of range is raised from a subsequent iteration of the for loop.
It's hard to know why without running the code, but for example an instance with no volumes like this case would cause that line to fail.
You could debug like this to inspect the offending data:
try:
create_time = item['Instances'][0]['BlockDeviceMappings'][0]['Ebs']['AttachTime'].strftime("%A, %d. %B %Y %I:%M%p")
except Exception as e:
import pdb; pdb.set_trace()
Or this if not attached to a shell:
try:
create_time = item['Instances'][0]['BlockDeviceMappings'][0]['Ebs']['AttachTime'].strftime("%A, %d. %B %Y %I:%M%p")
except Exception as e:
print("Dumping offending item:")
print(item)
raise e
Secondly, while the AttachTime might be suitable for your use case, it's not necessarily the time at which the volume was created, since they can be created then attached to an instance. If you need the actual creation time, you need to make a second call to describe_volume_status and use the CreateTime field.