How to define "snapshot" in python code

Hello.

I answered the question at the URL below, but I fixed the indentation throughout the code to eliminate any indentation-related errors.
https://repost.aws/questions/QUyMDhAVNeT52jVO68wGgdfA/made-suggested-indents-but-right-back-at-same-error-message#ANTQOlOs0pQD2kOA7zumPanw

import boto3
import os
from datetime import datetime

# Define regions
# SOURCE_REGION = "us-west-1"  # N. California
SOURCE_REGION = "us-west-2"  # Oregon
DEST_REGION = "us-west-2"    # Oregon
NUM_SNAPSHOTS = 2            # Number of snapshots to process

def lambda_handler(event, context):
# Create RDS clients for both regions
    source_rds = boto3.client('rds', region_name=SOURCE_REGION)
    dest_rds = boto3.client('rds', region_name=DEST_REGION)

# Step 1: Delete oldest manual snapshots in destination region
    delete_oldest_snapshots(dest_rds, NUM_SNAPSHOTS)

# Step 2: Copy latest system snapshots from source to destination
    copy_latest_snapshots(source_rds, dest_rds, NUM_SNAPSHOTS)

    return {
        'statusCode': 200,
        'body': f'Successfully processed {NUM_SNAPSHOTS} snapshots'
    }

def delete_oldest_snapshots(dest_rds, count):
# Get all manual snapshots in destination region
    response = dest_rds.describe_db_snapshots(SnapshotType='manual')

# Sort snapshots by creation time (oldest first)
    snapshots = sorted(response['DBSnapshots'], key=lambda s: s['SnapshotCreateTime'])

# Delete the oldest 'count' snapshots
    for i, snapshot in enumerate(snapshots):
        if i >= count:
            break

        snapshot_id = snapshot['DBSnapshotIdentifier']
        print(f"Deleting snapshot: {snapshot_id}")

        try:
            dest_rds.delete_db_snapshot(DBSnapshotIdentifier=snapshot_id)
            print(f"Successfully deleted snapshot: {snapshot_id}")
        except Exception as e:
            print(f"Error deleting snapshot {snapshot_id}: {str(e)}")

def copy_latest_snapshots(source_rds, dest_rds, count):
# Get all automated snapshots in source region
    response = source_rds.describe_db_snapshots(SnapshotType='automated')

    # Sort snapshots by creation time (newest first)
    snapshots = sorted(response['DBSnapshots'], 
        key=lambda s: s['SnapshotCreateTime'], 
        reverse=True
    )

    # Get today's date for naming
    today = datetime.now().strftime("%Y-%m-%d")

    # Define the database names based on your example
    #  "amgen", "alpine"
    db_names = [
        "demo", "drtest20240314"
    ]

    # Copy the newest 'count' snapshots
    for i, snapshot in enumerate(snapshots[:count]):
        if i >= count:
            break

        source_snapshot_id = snapshot['DBSnapshotIdentifier']
        db_instance_id = snapshot['DBInstanceIdentifier']

        # Use the corresponding db name from the list if available
        db_name = db_names[i] if i < len(db_names) else db_instance_id

        # Create target snapshot name
        target_snapshot_id = f"copy-rds-db-{db_name}-{today}"

        print(f"Copying snapshot {source_snapshot_id} to {target_snapshot_id}")

        try:
        # Create ARN for source snapshot
            source_arn = snapshot['DBSnapshotArn']

        # Copy the snapshot
            dest_rds.copy_db_snapshot(
                SourceDBSnapshotIdentifier=source_arn,
                TargetDBSnapshotIdentifier=target_snapshot_id,
                SourceRegion=SOURCE_REGION
            )
            print(f"Successfully initiated copy of {source_snapshot_id} to {target_snapshot_id}")
        except Exception as e:
            print(f"Error copying snapshot {source_snapshot_id}: {str(e)}")

The error "name 'snapshot' is not defined" is occurring because your indentation in the delete_oldest_snapshots function is incorrect. The line snapshot_id = snapshot['DBSnapshotIdentifier'] and the code below it are not properly indented within the for loop.

In Python, indentation defines code blocks, so when your indentation is incorrect, Python treats the code as being outside of the loop where the snapshot variable is defined. This causes the error because snapshot is only defined within the scope of the for loop.

To fix this issue, you need to properly indent the code inside the for loop in the delete_oldest_snapshots function. Here's how the corrected function should look:

def delete_oldest_snapshots(dest_rds, count):
# Get all manual snapshots in destination region
response = dest_rds.describe_db_snapshots(SnapshotType='manual')

# Sort snapshots by creation time (oldest first)
snapshots = sorted(response['DBSnapshots'], key=lambda s: s['SnapshotCreateTime'])

# Delete the oldest 'count' snapshots
for i, snapshot in enumerate(snapshots):
if i >= count:
break

snapshot_id = snapshot['DBSnapshotIdentifier']
print(f"Deleting snapshot: {snapshot_id}")

try:
dest_rds.delete_db_snapshot(DBSnapshotIdentifier=snapshot_id)
print(f"Successfully deleted snapshot: {snapshot_id}")
except Exception as e:
print(f"Error deleting snapshot {snapshot_id}: {str(e)}")

Notice that all the code that uses the snapshot variable is indented to be inside the for loop. This ensures that snapshot is defined when you try to access it.

The same indentation issue appears to exist in your copy_latest_snapshots function as well, so you'll need to fix the indentation there too.
Sources
Troubleshooting cluster deployment issues - AWS ParallelCluster