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DynamoDB Configurations Details

The Dynamodb event will automatically handle many common things done when eventing off a DynamoDB stream. Developers then have the ability to further extend that functionality with custom middleware. Below is a full list of all the configurations available and examples of their use.

Examples

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Lambda Configuration

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functions:
    ddb-handler:
        handler: service/handlers/dynamodb.handle
        memorySize: 512
        timeout: 30
        events:
            - stream:
                type: dynamodb
                arn:
                Fn::GetAtt: [ SomeDDBTable, StreamArn ]

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from acai_aws.dynamodb.requirements import requirements
from acai_aws.common import logger

@requirements(
    before=log_something,
    operations=['created', 'deleted', 'updated'],
    data_class=SomeClass,
    raise_operation_error=True,
    raise_body_error=True,
    schema='service/openapi.yml',
    required_body='v1-ddb-body', # or jsonschema dict
    after=alert_something,
)
def handle(event):
    for record in event.records:
        logger.log(log=record)

# example data class
class SomeClass:
    def __init__(self, record):
        for k, v in record.body.items():
            setattr(self, k, v)

# example before function
def log_something(records, requirements):
    if 'something' in requirements:
        logger.log(log=records) 

# example after function
def alert_something(records, result, requirements):
    if 'something' in result and 'alert' in requirements:
        logger.log(log=records)

Requirements Configuration Options

option type required default description
before func no None a custom function to be ran before your records are pulled
after func no None a custom function to be ran after your records are pulled
data_class class no None a custom class that will be passed instead of the records object
operations list no ['created', 'updated', 'deleted'] will only run if record was created from the listed operation
raise_operation_error bool no False will raise exception if operation of record is not from listed operations
raise_body_error bool no False will raise exception if body of record does not match schema provided
required_body str or dict no None will validate body of record against this schema
schema str no None file path pointing to the location of the openapi.yml file

DynamoDB Record Properties

property type description
body object the new image of dynamodb record; created or updated
created float the approximate creationDate time
expired bool whether the ttl has expired
id str the id of the event which invoked the lambda
identity object the identity who triggered the dynamodb change
keys object the keys of DynamoDB record
name str the name of the event which invoked the lambda
new_image object the new image of dynamodb record; created or updated
old_image object the old image of dynamodb record; updated or deleted
operation str triggered operation lambda (create, update, delete)
region str the region the record is from
size int the size in bytes of the record
source str the source of the event which invoked the lambda
source_arn str the event source arn
stream_type str the stream view type
version str the event version
operation str enum of created, deleted, updated

record.region

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print(record.region);

# output
'us-east-2'

record.id

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print(record.id);

# output
'9a37c0d03eb60f7cf70cabc823de9907'

record.name

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print(record.name);

# output
'INSERT'

record.source

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print(record.source);

# output
'aws:dynamodb'

record.keys

Info

This is converted from the original DDB JSON to standard json

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print(record.keys);

# output
{
    'example_id': '123456789'
}

record.old_image

Info

This is converted from the original DDB JSON to standard json

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print(record.old_image);

# output
{
    'old_data': '123456789'
}

record.new_image

Info

This is converted from the original DDB JSON to standard json

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print(record.new_image);

# output
{
    'new_data': '123456789'
}

record.body

Info

This is converted from the original DDB JSON to standard json from new_image

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print(record.body);

# output
{
    'new_data': '123456789'
}

record.operation

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print(record.operation);

# output
'create'

record.source_arn

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print(record.source_arn);

# output
'arn:aws:dynamodb:us-east-1:771875143460:table/test-example/stream/2019-10-04T23:18:26.340'

record.version

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print(record.version);

# output
'1.1'

record.stream_type

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print(record.stream_type);

# output
'NEW_AND_OLD_IMAGES'

record.size

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print(record.size);

# output
1124

record.created

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print(record.created);

# output (unix timestamp)
1538695200.0

record.identity

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print(record.identity);

# output
{
    'type': 'Service',
    'principalId': 'dynamodb.amazonaws.com'
}

record.expired

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print(record.expired);

# output
False