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import warnings
from typing import List, Optional, Union
from airflow.exceptions import AirflowException
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
[docs]AVAILABLE_METHODS = ['APPEND', 'REPLACE', 'UPSERT']
[docs]class S3ToRedshiftOperator(BaseOperator):
"""
Executes an COPY command to load files from s3 to Redshift
.. seealso::
For more information on how to use this operator, take a look at the guide:
:ref:`howto/operator:S3ToRedshiftOperator`
:param schema: reference to a specific schema in redshift database
:type schema: str
:param table: reference to a specific table in redshift database
:type table: str
:param s3_bucket: reference to a specific S3 bucket
:type s3_bucket: str
:param s3_key: reference to a specific S3 key
:type s3_key: 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 column_list: list of column names to load
:type column_list: List[str]
:param copy_options: reference to a list of COPY options
:type copy_options: list
:param method: Action to be performed on execution. Available ``APPEND``, ``UPSERT`` and ``REPLACE``.
:type method: str
:param upsert_keys: List of fields to use as key on upsert action
:type upsert_keys: List[str]
"""
[docs] template_fields = ('s3_bucket', 's3_key', 'schema', 'table', 'column_list', 'copy_options')
def __init__(
self,
*,
schema: str,
table: str,
s3_bucket: str,
s3_key: str,
redshift_conn_id: str = 'redshift_default',
aws_conn_id: str = 'aws_default',
verify: Optional[Union[bool, str]] = None,
column_list: Optional[List[str]] = None,
copy_options: Optional[List] = None,
autocommit: bool = False,
method: str = 'APPEND',
upsert_keys: Optional[List[str]] = None,
**kwargs,
) -> None:
if 'truncate_table' in kwargs:
warnings.warn(
"""`truncate_table` is deprecated. Please use `REPLACE` method.""",
DeprecationWarning,
stacklevel=2,
)
if kwargs['truncate_table']:
method = 'REPLACE'
kwargs.pop('truncate_table', None)
super().__init__(**kwargs)
self.schema = schema
self.table = table
self.s3_bucket = s3_bucket
self.s3_key = s3_key
self.redshift_conn_id = redshift_conn_id
self.aws_conn_id = aws_conn_id
self.verify = verify
self.column_list = column_list
self.copy_options = copy_options or []
self.autocommit = autocommit
self.method = method
self.upsert_keys = upsert_keys
if self.method not in AVAILABLE_METHODS:
raise AirflowException(f'Method not found! Available methods: {AVAILABLE_METHODS}')
def _build_copy_query(self, copy_destination: str, credentials_block: str, copy_options: str) -> str:
column_names = "(" + ", ".join(self.column_list) + ")" if self.column_list else ''
return f"""
COPY {copy_destination} {column_names}
FROM 's3://{self.s3_bucket}/{self.s3_key}'
credentials
'{credentials_block}'
{copy_options};
"""
def _get_table_primary_key(self, postgres_hook):
sql = """
select kcu.column_name
from information_schema.table_constraints tco
join information_schema.key_column_usage kcu
on kcu.constraint_name = tco.constraint_name
and kcu.constraint_schema = tco.constraint_schema
and kcu.constraint_name = tco.constraint_name
where tco.constraint_type = 'PRIMARY KEY'
and kcu.table_schema = %s
and kcu.table_name = %s
"""
result = postgres_hook.get_records(sql, (self.schema, self.table))
if len(result) == 0:
raise AirflowException(
f"""
No primary key on {self.schema}.{self.table}.
Please provide keys on 'upsert_keys' parameter.
"""
)
return [row[0] for row in result]
[docs] def execute(self, context) -> None:
postgres_hook = PostgresHook(postgres_conn_id=self.redshift_conn_id)
conn = S3Hook.get_connection(conn_id=self.aws_conn_id)
credentials_block = None
if conn.extra_dejson.get('role_arn', False):
credentials_block = f"aws_iam_role={conn.extra_dejson['role_arn']}"
else:
s3_hook = S3Hook(aws_conn_id=self.aws_conn_id, verify=self.verify)
credentials = s3_hook.get_credentials()
credentials_block = build_credentials_block(credentials)
copy_options = '\n\t\t\t'.join(self.copy_options)
destination = f'{self.schema}.{self.table}'
copy_destination = f'#{self.table}' if self.method == 'UPSERT' else destination
copy_statement = self._build_copy_query(copy_destination, credentials_block, copy_options)
if self.method == 'REPLACE':
sql = f"""
BEGIN;
DELETE FROM {destination};
{copy_statement}
COMMIT
"""
elif self.method == 'UPSERT':
keys = self.upsert_keys or postgres_hook.get_table_primary_key(self.table, self.schema)
if not keys:
raise AirflowException(
f"No primary key on {self.schema}.{self.table}. Please provide keys on 'upsert_keys'"
)
where_statement = ' AND '.join([f'{self.table}.{k} = {copy_destination}.{k}' for k in keys])
sql = f"""
CREATE TABLE {copy_destination} (LIKE {destination});
{copy_statement}
BEGIN;
DELETE FROM {destination} USING {copy_destination} WHERE {where_statement};
INSERT INTO {destination} SELECT * FROM {copy_destination};
COMMIT
"""
else:
sql = copy_statement
self.log.info('Executing COPY command...')
postgres_hook.run(sql, self.autocommit)
self.log.info("COPY command complete...")