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This module contains operators to replicate records from
DynamoDB table to S3.
from __future__ import annotations

import json
from copy import copy
from decimal import Decimal
from os.path import getsize
from tempfile import NamedTemporaryFile
from typing import IO, TYPE_CHECKING, Any, Callable, Sequence
from uuid import uuid4

from airflow.models import BaseOperator
from import DynamoDBHook
from import S3Hook

    from airflow.utils.context import Context

[docs]class JSONEncoder(json.JSONEncoder): """Custom json encoder implementation"""
[docs] def default(self, obj): """Convert decimal objects in a json serializable format.""" if isinstance(obj, Decimal): return float(obj) return super().default(obj)
def _convert_item_to_json_bytes(item: dict[str, Any]) -> bytes: return (json.dumps(item, cls=JSONEncoder) + "\n").encode("utf-8") def _upload_file_to_s3( file_obj: IO, bucket_name: str, s3_key_prefix: str, aws_conn_id: str = "aws_default" ) -> None: s3_client = S3Hook(aws_conn_id=aws_conn_id).get_conn() s3_client.upload_file(, Bucket=bucket_name, Key=s3_key_prefix + str(uuid4()), )
[docs]class DynamoDBToS3Operator(BaseOperator): """ Replicates records from a DynamoDB table to S3. It scans a DynamoDB table and writes the received records to a file on the local filesystem. It flushes the file to S3 once the file size exceeds the file size limit specified by the user. Users can also specify a filtering criteria using dynamodb_scan_kwargs to only replicate records that satisfy the criteria. .. seealso:: For more information on how to use this operator, take a look at the guide: :ref:`howto/transfer:DynamoDBToS3Operator` :param dynamodb_table_name: Dynamodb table to replicate data from :param s3_bucket_name: S3 bucket to replicate data to :param file_size: Flush file to s3 if file size >= file_size :param dynamodb_scan_kwargs: kwargs pass to <> :param s3_key_prefix: Prefix of s3 object key :param process_func: How we transforms a dynamodb item to bytes. By default we dump the json :param aws_conn_id: The Airflow connection used for AWS credentials. If this is None or empty then the default boto3 behaviour is used. If running Airflow in a distributed manner and aws_conn_id is None or empty, then default boto3 configuration would be used (and must be maintained on each worker node). """ # noqa: E501
[docs] template_fields: Sequence[str] = ( "s3_bucket_name", "s3_key_prefix", "dynamodb_table_name",
[docs] template_fields_renderers = { "dynamodb_scan_kwargs": "json",
} def __init__( self, *, dynamodb_table_name: str, s3_bucket_name: str, file_size: int, dynamodb_scan_kwargs: dict[str, Any] | None = None, s3_key_prefix: str = "", process_func: Callable[[dict[str, Any]], bytes] = _convert_item_to_json_bytes, aws_conn_id: str = "aws_default", **kwargs, ) -> None: super().__init__(**kwargs) self.file_size = file_size self.process_func = process_func self.dynamodb_table_name = dynamodb_table_name self.dynamodb_scan_kwargs = dynamodb_scan_kwargs self.s3_bucket_name = s3_bucket_name self.s3_key_prefix = s3_key_prefix self.aws_conn_id = aws_conn_id
[docs] def execute(self, context: Context) -> None: hook = DynamoDBHook(aws_conn_id=self.aws_conn_id) table = hook.get_conn().Table(self.dynamodb_table_name) scan_kwargs = copy(self.dynamodb_scan_kwargs) if self.dynamodb_scan_kwargs else {} err = None f: IO[Any] with NamedTemporaryFile() as f: try: f = self._scan_dynamodb_and_upload_to_s3(f, scan_kwargs, table) except Exception as e: err = e raise e finally: if err is None: _upload_file_to_s3(f, self.s3_bucket_name, self.s3_key_prefix, self.aws_conn_id)
def _scan_dynamodb_and_upload_to_s3(self, temp_file: IO, scan_kwargs: dict, table: Any) -> IO: while True: response = table.scan(**scan_kwargs) items = response["Items"] for item in items: temp_file.write(self.process_func(item)) if "LastEvaluatedKey" not in response: # no more items to scan break last_evaluated_key = response["LastEvaluatedKey"] scan_kwargs["ExclusiveStartKey"] = last_evaluated_key # Upload the file to S3 if reach file size limit if getsize( >= self.file_size: _upload_file_to_s3(temp_file, self.s3_bucket_name, self.s3_key_prefix, self.aws_conn_id) temp_file.close() temp_file = NamedTemporaryFile() return temp_file

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