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"""Transfers data from AWS Redshift into a S3 Bucket.""" from typing import List, Optional, Union from airflow.models import BaseOperator from airflow.providers.amazon.aws.hooks.s3 import S3Hook from airflow.providers.amazon.aws.utils.redshift import build_credentials_block from airflow.providers.postgres.hooks.postgres import PostgresHook from airflow.utils.decorators import apply_defaults class RedshiftToS3Operator(BaseOperator): """ Executes an UNLOAD command to s3 as a CSV with headers :param s3_bucket: reference to a specific S3 bucket :type s3_bucket: str :param s3_key: reference to a specific S3 key. If ``table_as_file_name`` is set to False, this param must include the desired file name :type s3_key: str :param schema: reference to a specific schema in redshift database Applicable when ``table`` param provided. :type schema: str :param table: reference to a specific table in redshift database Used when ``select_query`` param not provided. :type table: str :param select_query: custom select query to fetch data from redshift database :type select_query: str :param redshift_conn_id: reference to a specific redshift database :type redshift_conn_id: str :param aws_conn_id: reference to a specific S3 connection If the AWS connection contains 'aws_iam_role' in ``extras`` the operator will use AWS STS credentials with a token https://docs.aws.amazon.com/redshift/latest/dg/copy-parameters-authorization.html#copy-credentials :type aws_conn_id: str :param verify: Whether or not to verify SSL certificates for S3 connection. By default SSL certificates are verified. You can provide the following values: - ``False``: do not validate SSL certificates. SSL will still be used (unless use_ssl is False), but SSL certificates will not be verified. - ``path/to/cert/bundle.pem``: A filename of the CA cert bundle to uses. You can specify this argument if you want to use a different CA cert bundle than the one used by botocore. :type verify: bool or str :param unload_options: reference to a list of UNLOAD options :type unload_options: list :param autocommit: If set to True it will automatically commit the UNLOAD statement. Otherwise it will be committed right before the redshift connection gets closed. :type autocommit: bool :param include_header: If set to True the s3 file contains the header columns. :type include_header: bool :param table_as_file_name: If set to True, the s3 file will be named as the table. Applicable when ``table`` param provided. :type table_as_file_name: bool """ template_fields = ("s3_bucket", "s3_key", "schema", "table", "unload_options") template_ext = () ui_color = "#ededed" @apply_defaults def __init__( # pylint: disable=too-many-arguments self, *, s3_bucket: str, s3_key: str, schema: str = None, table: str = None, select_query: str = None, redshift_conn_id: str = "redshift_default", aws_conn_id: str = "aws_default", verify: Optional[Union[bool, str]] = None, unload_options: Optional[List] = None, autocommit: bool = False, include_header: bool = False, table_as_file_name: bool = True, # Set to True by default for not breaking current workflows **kwargs, ) -> None: super().__init__(**kwargs) self.s3_bucket = s3_bucket self.s3_key = f"{s3_key}/{table}_" if (table and table_as_file_name) else s3_key self.schema = schema self.table = table self.redshift_conn_id = redshift_conn_id self.aws_conn_id = aws_conn_id self.verify = verify self.unload_options = unload_options or [] # type: List self.autocommit = autocommit self.include_header = include_header self.table_as_file_name = table_as_file_name self._select_query = None if select_query: self._select_query = select_query elif self.schema and self.table: self._select_query = f"SELECT * FROM {self.schema}.{self.table}" else: raise ValueError( "Please provide both `schema` and `table` params or `select_query` to fetch the data." ) if self.include_header and "HEADER" not in [ uo.upper().strip() for uo in self.unload_options ]: self.unload_options = list(self.unload_options) + [ "HEADER", ] def _build_unload_query( self, credentials_block: str, select_query: str, s3_key: str, unload_options: str, ) -> str: return f""" UNLOAD ('{select_query}') TO 's3://{self.s3_bucket}/{s3_key}' with credentials '{credentials_block}' {unload_options}; """ def execute(self, context) -> None: postgres_hook = PostgresHook(postgres_conn_id=self.redshift_conn_id) s3_hook = S3Hook(aws_conn_id=self.aws_conn_id, verify=self.verify) credentials = s3_hook.get_credentials() credentials_block = build_credentials_block(credentials) unload_options = "\n\t\t\t".join(self.unload_options) unload_query = self._build_unload_query( credentials_block, self._select_query, self.s3_key, unload_options ) self.log.info("Executing UNLOAD command...") postgres_hook.run(unload_query, self.autocommit) self.log.info("UNLOAD command complete...")