lambda function fails with s3 key error. in amazon web services - amazon-web-services

Question

I have a lambda function that moves files from one s3 bucket to another :
import json
import boto3
from datetime import datetime, timedelta
def lambda_handler(event, context):
# TODO implement
SOURCE_BUCKET = 'source-bucket'
DESTINATION_BUCKET = 'destination-bucket'
s3_client = boto3.client('s3')
# Create a reusable Paginator
paginator = s3_client.get_paginator('list_objects_v2')
# Create a PageIterator from the Paginator
page_iterator = paginator.paginate(Bucket=SOURCE_BUCKET)
# Loop through each object, looking for ones older than a given time period
for page in page_iterator:
for object in page['Contents']:
if object['LastModified'] < datetime.now().astimezone() - timedelta(hours=1): # <-- Change time period here
print(f"Moving {object['Key']}")
# Copy object
s3_client.copy_object(
ACL='bucket-owner-full-control',
Bucket=DESTINATION_BUCKET,
Key=object['Key'],
CopySource={'Bucket':SOURCE_BUCKET, 'Key':object['Key']}
)
# Delete original object
s3_client.delete_object(Bucket=SOURCE_BUCKET, Key=object['Key'])
I am getting error :
Response:
{
"errorMessage": "'Contents'",
"errorType": "KeyError",
"stackTrace": [
" File \"/var/task/lambda_function.py\", line 21, in lambda_handler\n for object in page['Contents']:\n"
]
}
Request ID:
"518e0f39-63e4-43df-842d-b73d56f83cd8"
Function Logs:
START RequestId: 518e0f39-63e4-43df-842d-b73d56f83cd8 Version: $LATEST
[ERROR] KeyError: 'Contents'
Traceback (most recent call last):
  File "/var/task/lambda_function.py", line 21, in lambda_handler
    for object in page['Contents']:END RequestId: 518e0f39-63e4-43df-842d-b73d56f83cd8
REPORT RequestId: 518e0f39-63e4-43df-842d-b73d56f83cd8 Duration: 1611.00 ms Billed Duration: 1700 ms Memory Size: 128 MB Max Memory Used: 76 MB Init Duration: 248.12 ms
can someone help here. It has moved all the files but still giving me error.

Answer 1

This is assuming that the key Contents is always returned. If there are not objects in the bucket this will not exist.
Add a simple if "Contents" in page to handle it not always existing.
So your function code might look like
import json
import boto3
from datetime import datetime, timedelta
def lambda_handler(event, context):
# TODO implement
SOURCE_BUCKET = 'source-bucket'
DESTINATION_BUCKET = 'destination-bucket'
s3_client = boto3.client('s3')
# Create a reusable Paginator
paginator = s3_client.get_paginator('list_objects_v2')
# Create a PageIterator from the Paginator
page_iterator = paginator.paginate(Bucket=SOURCE_BUCKET)
# Loop through each object, looking for ones older than a given time period
for page in page_iterator:
if "Contents" in page:
for object in page['Contents']:
if object['LastModified'] < datetime.now().astimezone() - timedelta(hours=1): # <-- Change time period here
print(f"Moving {object['Key']}")
# Copy object
s3_client.copy_object(
ACL='bucket-owner-full-control',
Bucket=DESTINATION_BUCKET,
Key=object['Key'],
CopySource={'Bucket':SOURCE_BUCKET, 'Key':object['Key']}
)
# Delete original object
s3_client.delete_object(Bucket=SOURCE_BUCKET, Key=object['Key'])
else:
print("No Contents key for page!")