Slack SlackAPIPostOperator not working properly in airflow composer - airflow

Question

I am trying to send notifications tom slack when DAG run fails in airflow in google cloud composer. The version of airflow used is 1.9 so I cannot use slack webhooks. But when I add my code , i get this strange error : No module named 'slackclient'
I am not sure how to make this work in google cloud composer. I tried installing the slack package by adding PyPi variables in composer. But till now nothing works.
Anybody please help?
My code:
from slackclient import SlackClient
from airflow.operators.slack_operator import SlackAPIPostOperator
slack_channel= 'gsdgsdg'
slack_token = 'ssdfhfdrtxcuweiwvbnw54135f543589zdklchvfö'
def task_fail_slack_alert(context):
slack_msg = \
"""
:red_circle: Task Failed.
*Task*: {task}
*Dag*: {dag}
*Execution Time*: {exec_date}
*Log Url*: {log_url}
""".format(task=context.get('task_instance'
).task_id, dag=context.get('task_instance').dag_id,
ti=context.get('task_instance'),
exec_date=context.get('execution_date'),
log_url=context.get('task_instance').log_url)
failed_alert = SlackAPIPostOperator(
task_id = 'airflow_etl_failed',
channel = slack_channel,
token = slack_token,
text = slack_msg
)
return failed_alert.execute(context=context)

Answer 1

The SlackAPIPostOperator requires the slackclient library installed, which is usually done using
$ pip install apache-airflow[slack]
BUT as you're running Google Cloud Composer this clearly won't work. Instead, you can install slackclient using the environment's PyPI package installer.
Navigate to the
Google Cloud Console -> Google Cloud Composer -> Your Airflow environment
and then choose the "PYPI PACKAGES" tab. You can then specify the slackclient module to be installed, and maybe pin it at a version (>=1.3.2 ?)