airflow plugins not getting picked up correctly

Question

We are using Apache 1.9.0. I have written a snowflake hook plugin. I have placed the hook in the $AIRFLOW_HOME/plugins directory.

$AIRFLOW_HOME
  +--plugins
    +--snowflake_hook2.py

snowflake_hook2.py

# This is the base class for a plugin
from airflow.plugins_manager import AirflowPlugin

# This is necessary to expose the plugin in the Web interface
from flask import Blueprint
from flask_admin import BaseView, expose
from flask_admin.base import MenuLink

# This is the base hook for connecting to a database
from airflow.hooks.dbapi_hook import DbApiHook

# This is the snowflake provided Connector
import snowflake.connector

# This is the default python logging package
import logging

class SnowflakeHook2(DbApiHook):
    """
    Airflow Hook to communicate with Snowflake
    This is implemented as a Plugin
    """
    def __init__(self, connname_in='snowflake_default', db_in='default', wh_in='default', schema_in='default'):
        logging.info('# Connecting to {0}'.format(connname_in))
        self.conn_name_attr = 'snowflake_conn_id'
        self.connname = connname_in
        self.superconn = super().get_connection(self.connname) #gets the values from Airflow

        {SNIP - Connection stuff that works}
        self.cur = self.conn.cursor()

    def query(self,q,params=None):
        """From jmoney's db_wrapper allows return of a full list of rows(tuples)"""
        if params == None: #no Params, so no insertion
            self.cur.execute(q)
        else: #make the parameter substitution
            self.cur.execute(q,params)
        self.results = self.cur.fetchall()
        self.rowcount = self.cur.rowcount
        self.columnnames = [colspec[0] for colspec in self.cur.description]
        return self.results
    {SNIP - Other class functions}

class SnowflakePluginClass(AirflowPlugin):
    name = "SnowflakePluginModule"
    hooks = [SnowflakeHook2]
    operators = []

So I went ahead and put some print statements in Airflows plugin_manager to try and get a better handle on what is happening. After restarting the webserver and running airflow list_dags, these lines were showing the "new module name" (and no errors

SnowflakePluginModule [<class '__home__ubuntu__airflow__plugins_snowflake_hook2.SnowflakeHook2'>]
hook_module -  airflow.hooks.snowflakepluginmodule
INTEGRATING airflow.hooks.snowflakepluginmodule
snowflakepluginmodule <module 'airflow.hooks.snowflakepluginmodule'>

As this is consistent with what the documentation says, I should be fine using this in my DAG:

from airflow import DAG
from airflow.hooks.snowflakepluginmodule import SnowflakeHook2 
from airflow.operators.python_operator import PythonOperator

But the web throws this error

Broken DAG: [/home/ubuntu/airflow/dags/test_sf2.py] No module named 'airflow.hooks.snowflakepluginmodule'

So the question is, What am I doing wrong? Or have I uncovered a bug?

Answer 1

You need to import as below:

from airflow import DAG
from airflow.hooks import SnowflakeHook2 
from airflow.operators.python_operator import PythonOperator

OR

from airflow import DAG
from airflow.hooks.SnowflakePluginModule import SnowflakeHook2 
from airflow.operators.python_operator import PythonOperator