AWS Lambda：RDS快照-KeyError

Question

I am setting up a Lambda function to take daily snapshots of RDS instances based on this script . I am running with the python3 interpreter.

import boto3
import datetime


def lambda_handler(event, context):
    print("Connecting to RDS")
    client = boto3.client('rds')

    # Instance to backup
    dbInstances = ['testdb']

    for dbInstance in dbInstances:
        print("RDS snapshot backups started at %s...\n" % datetime.datetime.now())

        client.create_db_snapshot(
            DBInstanceIdentifier=dbInstance,
            DBSnapshotIdentifier=dbInstance+'{}'.format(datetime.datetime.now().strftime("%y-%m-%d-%H")),
            Tags=[
                {
                    'Key': 'Name',
                    'Value': 'dbInstace'

                },
            ]
        )


        for snapshot in client.describe_db_snapshots(DBInstanceIdentifier=dbInstance, MaxRecords=50)['DBSnapshots']:
            createTs = snapshot['SnapshotCreateTime'].replace(tzinfo=None)
            if createTs < datetime.datetime.now() - datetime.timedelta(days=30):
                print("Deleting snapshot id:", snapshot['DBSnapshotIdentifier'])
                client.delete_db_snapshot(
                    DBSnapshotIdentifier=snapshot['DBSnapshotIdentifier']
                )

The script does work for creating a snapshot; however I also get this error every time it runs, so I do not think it will properly delete snapshots.

'SnapshotCreateTime': KeyError
Traceback (most recent call last):
  File "/var/task/lambda_function.py", line 29, in lambda_handler
    createTs = snapshot['SnapshotCreateTime'].replace(tzinfo=None)
KeyError: 'SnapshotCreateTime'

Traceback (most recent call last):
  File "/var/runtime/awslambda/bootstrap.py", line 226, in handle_event_request
    result = request_handler(json_input, context)
  File "/var/task/lambda_function.py", line 29, in lambda_handler
    createTs = snapshot['SnapshotCreateTime'].replace(tzinfo=None)
KeyError: 'SnapshotCreateTime'

The problem seems to be with this line in particular:

createTs = snapshot['SnapshotCreateTime'].replace(tzinfo=None)

Why is this happening?

Answer 1

I suspect that you are seeing KeyError because the snapshot is still in progress and SnapshotCreateTime is not populated in the returned dict yet.

In this case the PercentProgress will be less than 100.

for snap in snapshots['DBSnapshots']:
    if ('SnapshotCreateTime' in snap):
        print snap['SnapshotCreateTime']
    else:
        print 'No create time available'

    if ('PercentProgress' in snap):
        print snap['PercentProgress']