Add snowflake to slack operator (#9023)

Addition of a new `snowflake_to_slack` operator. The operator
allows you to run a SQL statement against Snowflake and render
the results into a Slack message.

* Add snowflake_to_slack operator to example dag
* Add type hints to operator and clean example dag

CONTRIBUTING.rst

@@ -468,6 +468,7 @@ opsgenie                   http
 postgres                   amazon
 sftp                       ssh
 slack                      http
+snowflake                  slack
 ========================== ===========================
 
   .. END PACKAGE DEPENDENCIES HERE

airflow/providers/dependencies.json

@@ -64,5 +64,8 @@
   ],
   "slack": [
     "http"
+  ],
+  "snowflake": [
+    "slack"
   ]
 }

airflow/providers/snowflake/example_dags/example_snowflake.py

@@ -23,16 +23,24 @@
 from airflow import DAG
 from airflow.providers.snowflake.operators.s3_to_snowflake import S3ToSnowflakeTransferOperator
 from airflow.providers.snowflake.operators.snowflake import SnowflakeOperator
+from airflow.providers.snowflake.operators.snowflake_to_slack import SnowflakeToSlackOperator
 from airflow.utils.dates import days_ago
 
 SNOWFLAKE_CONN_ID = os.environ.get('SNOWFLAKE_CONN_ID', 'snowflake_default')
+SLACK_CONN_ID = os.environ.get('SLACK_CONN_ID', 'slack_default')
 # TODO: should be able to rely on connection's schema, but currently param required by S3ToSnowflakeTransfer
 SNOWFLAKE_SCHEMA = os.environ.get('SNOWFLAKE_SCHEMA', 'public')
 SNOWFLAKE_STAGE = os.environ.get('SNOWFLAKE_STAGE', 'airflow')
 SNOWFLAKE_SAMPLE_TABLE = os.environ.get('SNOWFLAKE_SAMPLE_TABLE', 'snowflake_sample_data.tpch_sf001.orders')
 SNOWFLAKE_LOAD_TABLE = os.environ.get('SNOWFLAKE_LOAD_TABLE', 'airflow_example')
 SNOWFLAKE_LOAD_JSON_PATH = os.environ.get('SNOWFLAKE_LOAD_PATH', 'example.json')
 
+SNOWFLAKE_SELECT_SQL = f"SELECT * FROM {SNOWFLAKE_SAMPLE_TABLE} LIMIT 100;"
+SNOWFLAKE_SLACK_SQL = f"SELECT O_ORDERKEY, O_CUSTKEY, O_ORDERSTATUS FROM {SNOWFLAKE_SAMPLE_TABLE} LIMIT 10;"
+SNOWFLAKE_SLACK_MESSAGE = "Results in an ASCII table:\n" \
+                          "```{{ results_df | tabulate(tablefmt='pretty', headers='keys') }}```"
+SNOWFLAKE_CREATE_TABLE_SQL = f"CREATE TRANSIENT TABLE IF NOT EXISTS {SNOWFLAKE_LOAD_TABLE}(data VARIANT);"
+
 default_args = {
     'owner': 'airflow',
     'start_date': days_ago(2),
@@ -47,22 +55,23 @@
 select = SnowflakeOperator(
     task_id='select',
     snowflake_conn_id=SNOWFLAKE_CONN_ID,
-    sql="""
-    SELECT *
-    FROM {0}
-    LIMIT 100;
-    """.format(SNOWFLAKE_SAMPLE_TABLE),
+    sql=SNOWFLAKE_SELECT_SQL,
     dag=dag,
 )
 
+slack_report = SnowflakeToSlackOperator(
+    task_id="slack_report",
+    sql=SNOWFLAKE_SLACK_SQL,
+    slack_message=SNOWFLAKE_SLACK_MESSAGE,
+    snowflake_conn_id=SNOWFLAKE_CONN_ID,
+    slack_conn_id=SLACK_CONN_ID,
+    dag=dag
+)
+
 create_table = SnowflakeOperator(
     task_id='create_table',
-    snowflake_conn_id='snowflake_conn_id',
-    sql="""
-    CREATE TRANSIENT TABLE IF NOT EXISTS {0} (
-        data VARIANT
-    );
-    """.format(SNOWFLAKE_LOAD_TABLE),
+    snowflake_conn_id=SNOWFLAKE_CONN_ID,
+    sql=SNOWFLAKE_CREATE_TABLE_SQL,
     schema=SNOWFLAKE_SCHEMA,
     dag=dag,
 )
@@ -78,4 +87,5 @@
     dag=dag,
 )
 
+select >> slack_report
 create_table >> copy_into_table

airflow/providers/snowflake/operators/snowflake_to_slack.py

@@ -0,0 +1,152 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+from typing import Iterable, Mapping, Optional, Union
+
+from pandas import DataFrame
+from tabulate import tabulate
+
+from airflow.exceptions import AirflowException
+from airflow.models import BaseOperator
+from airflow.providers.slack.hooks.slack_webhook import SlackWebhookHook
+from airflow.providers.snowflake.hooks.snowflake import SnowflakeHook
+from airflow.utils.decorators import apply_defaults
+
+
+class SnowflakeToSlackOperator(BaseOperator):
+    """
+    Executes an SQL statement in Snowflake and sends the results to Slack. The results of the query are
+    rendered into the 'slack_message' parameter as a Pandas dataframe using a JINJA variable called '{{
+    results_df }}'. The 'results_df' variable name can be changed by specifing a different
+    'results_df_name' parameter. The Tabulate library is added to the JINJA environment as a filter to
+    allow the dataframe to be rendered nicely. For example, set 'slack_message' to {{ results_df |
+    tabulate(tablefmt="pretty", headers="keys") }} to send the results to Slack as an ascii rendered table.
+
+    :param sql: The SQL statement to execute on Snowflake (templated)
+    :type sql: str
+    :param slack_message: The templated Slack message to send with the data returned from Snowflake.
+        You can use the default JINJA variable {{ results_df }} to access the pandas dataframe containing the
+        SQL results
+    :type slack_message: str
+    :param snowflake_conn_id: The Snowflake connection id
+    :type snowflake_conn_id: str
+    :param slack_conn_id: The connection id for Slack
+    :type slack_conn_id: str
+    :param results_df_name: The name of the JINJA template's dataframe variable, default is 'results_df'
+    :type results_df_name: str
+    :param parameters: The parameters to pass to the SQL query
+    :type parameters: Optional[Union[Iterable, Mapping]]
+    :param warehouse: The Snowflake virtual warehouse to use to run the SQL query
+    :type warehouse: Optional[str]
+    :param database: The Snowflake database to use for the SQL query
+    :type database: Optional[str]
+    :param schema: The schema to run the SQL against in Snowflake
+    :type schema: Optional[str]
+    :param role: The role to use when connecting to Snowflake
+    :type role: Optional[str]
+    :param slack_token: The token to use to authenticate to Slack. If this is not provided, the
+        'webhook_token' attribute needs to be specified in the 'Extra' JSON field against the slack_conn_id
+    :type slack_token: Optional[str]
+    """
+    template_fields = ['sql', 'slack_message']
+    template_ext = ['.sql', '.jinja', '.j2']
+    times_rendered = 0
+
+    @apply_defaults
+    def __init__(  # pylint: disable=too-many-arguments
+        self,
+        sql: str,
+        slack_message: str,
+        snowflake_conn_id: str = 'snowflake_default',
+        slack_conn_id: str = 'slack_default',
+        results_df_name: str = 'results_df',
+        parameters: Optional[Union[Iterable, Mapping]] = None,
+        warehouse: Optional[str] = None,
+        database: Optional[str] = None,
+        schema: Optional[str] = None,
+        role: Optional[str] = None,
+        slack_token: Optional[str] = None,
+        *args, **kwargs
+    ) -> None:
+        super(SnowflakeToSlackOperator, self).__init__(*args, **kwargs)
+
+        self.snowflake_conn_id = snowflake_conn_id
+        self.sql = sql
+        self.parameters = parameters
+        self.warehouse = warehouse
+        self.database = database
+        self.schema = schema
+        self.role = role
+        self.slack_conn_id = slack_conn_id
+        self.slack_token = slack_token
+        self.slack_message = slack_message
+        self.results_df_name = results_df_name
+
+    def _get_query_results(self) -> DataFrame:
+        snowflake_hook = self._get_snowflake_hook()
+
+        self.log.info('Running SQL query: %s', self.sql)
+        df = snowflake_hook.get_pandas_df(self.sql, parameters=self.parameters)
+        return df
+
+    def _render_and_send_slack_message(self, context, df) -> None:
+        # Put the dataframe into the context and render the JINJA template fields
+        context[self.results_df_name] = df
+        self.render_template_fields(context)
+
+        slack_hook = self._get_slack_hook()
+        self.log.info('Sending slack message: %s', self.slack_message)
+        slack_hook.execute()
+
+    def _get_snowflake_hook(self) -> SnowflakeHook:
+        return SnowflakeHook(snowflake_conn_id=self.snowflake_conn_id,
+                             warehouse=self.warehouse, database=self.database,
+                             role=self.role, schema=self.schema)
+
+    def _get_slack_hook(self) -> SlackWebhookHook:
+        return SlackWebhookHook(http_conn_id=self.slack_conn_id, message=self.slack_message,
+                                webhook_token=self.slack_token)
+
+    def render_template_fields(self, context, jinja_env=None) -> None:
+        # If this is the first render of the template fields, exclude slack_message from rendering since
+        # the snowflake results haven't been retrieved yet.
+        if self.times_rendered == 0:
+            fields_to_render: Iterable[str] = filter(lambda x: x != 'slack_message', self.template_fields)
+        else:
+            fields_to_render = self.template_fields
+
+        if not jinja_env:
+            jinja_env = self.get_template_env()
+
+        # Add the tabulate library into the JINJA environment
+        jinja_env.filters['tabulate'] = tabulate
+
+        self._do_render_template_fields(self, fields_to_render, context, jinja_env, set())
+        self.times_rendered += 1
+
+    def execute(self, context) -> None:
+        if not isinstance(self.sql, str):
+            raise AirflowException("Expected 'sql' parameter should be a string.")
+        if self.sql is None or self.sql.strip() == "":
+            raise AirflowException("Expected 'sql' parameter is missing.")
+        if self.slack_message is None or self.slack_message.strip() == "":
+            raise AirflowException("Expected 'slack_message' parameter is missing.")
+
+        df = self._get_query_results()
+        self._render_and_send_slack_message(context, df)
+
+        self.log.debug('Finished sending Snowflake data to Slack')

docs/operators-and-hooks-ref.rst

@@ -1218,7 +1218,8 @@ These integrations allow you to perform various operations within various servic
    * - `Snowflake <https://www.snowflake.com/>`__
      -
      - :mod:`airflow.providers.snowflake.hooks.snowflake`
-     - :mod:`airflow.providers.snowflake.operators.snowflake`
+     - :mod:`airflow.providers.snowflake.operators.snowflake`,
+       :mod:`airflow.providers.snowflake.operators.snowflake_to_slack`
      -
 
    * - `Vertica <https://www.vertica.com/>`__

tests/providers/snowflake/operators/test_snowflake_to_slack.py

@@ -0,0 +1,80 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+import unittest
+from unittest import mock
+
+from airflow.models import DAG
+from airflow.providers.snowflake.operators.snowflake_to_slack import SnowflakeToSlackOperator
+from airflow.utils import timezone
+
+TEST_DAG_ID = 'snowflake_to_slack_unit_test'
+DEFAULT_DATE = timezone.datetime(2017, 1, 1)
+
+
+class TestSnowflakeToSlackOperator(unittest.TestCase):
+    def setUp(self):
+        self.example_dag = DAG('unit_test_dag_snowflake_to_slack', start_date=DEFAULT_DATE)
+
+    @staticmethod
+    def _construct_operator(**kwargs):
+        operator = SnowflakeToSlackOperator(task_id=TEST_DAG_ID, **kwargs)
+        return operator
+
+    @mock.patch('airflow.providers.snowflake.operators.snowflake_to_slack.SnowflakeHook')
+    @mock.patch('airflow.providers.snowflake.operators.snowflake_to_slack.SlackWebhookHook')
+    def test_hooks_and_rendering(self, mock_slack_hook_class, mock_snowflake_hook_class):
+        operator_args = {
+            'snowflake_conn_id': 'snowflake_connection',
+            'slack_conn_id': 'slack_connection',
+            'sql': "sql {{ ds }}",
+            'results_df_name': 'xxxx',
+            'warehouse': 'test_warehouse',
+            'database': 'test_database',
+            'role': 'test_role',
+            'schema': 'test_schema',
+            'parameters': ['1', '2', '3'],
+            'slack_message': 'message: {{ ds }}, {{ xxxx }}',
+            'slack_token': 'test_token',
+            'dag': self.example_dag
+        }
+        snowflake_to_slack_operator = self._construct_operator(**operator_args)
+
+        snowflake_hook = mock_snowflake_hook_class.return_value
+        snowflake_hook.get_pandas_df.return_value = '1234'
+        slack_webhook_hook = mock_slack_hook_class.return_value
+
+        snowflake_to_slack_operator.run(start_date=DEFAULT_DATE, end_date=DEFAULT_DATE, ignore_ti_state=True)
+
+        # Test that the Snowflake hook is instantiated with the right parameters
+        mock_snowflake_hook_class.assert_called_once_with(database='test_database',
+                                                          role='test_role',
+                                                          schema='test_schema',
+                                                          snowflake_conn_id='snowflake_connection',
+                                                          warehouse='test_warehouse')
+
+        # Test that the get_pandas_df method is executed on the Snowflake hook with the prendered sql and
+        # correct params
+        snowflake_hook.get_pandas_df.assert_called_once_with('sql 2017-01-01', parameters=['1', '2', '3'])
+
+        # Test that the Slack hook is instantiated with the right parameters
+        mock_slack_hook_class.assert_called_once_with(http_conn_id='slack_connection',
+                                                      message='message: 2017-01-01, 1234',
+                                                      webhook_token='test_token')
+
+        # Test that the Slack hook's execute method gets run once
+        slack_webhook_hook.execute.assert_called_once()