Database IAM authentication failing from Google Dataflow instance

[Sumit Desai via user <us...@beam.apache.org>]

Hi all,
I have a Python based application that is using Apache beam in batch mode
and Google Dataflow as a worker. Yesterday, I was facing an issue passing
environmental variable  to Dataflow workers. I have temporarily commented
uses of the non.public Python package which required environmental
variables to function.

The first step of my pipeline is to read data from a database table as
input PCollection. The library that I have used as Input connector requires
DB build-in user and password and first step is getting executed
successfully.

Now, in second step, I want to update the DB rows (just 1 right now for
testing) to IN_PROGRESS. Here, I am using an IAM user which I am also using
outside of Dataflow. But  I am getting an error in dataflow pipeline -

*sqlalchemy.exc.OperationalError: (psycopg2.OperationalError) connection to
server at "xx.xx.xxx.xx", port 5432 failed: FATAL: AlloyDB IAM user
authentication failed for user "{iam_user}". *

I also tried creating a new IAM user corresponding to the service account I
am using for workers and provided it with the same permissions as the IAM
user outside of dataflow. But ,I am still seeing the same error. From logs,
I can see DB IP ,DB name and IAM users are correctly being passed.

Is there anything additional that I should be doing for an IAM user to
successfully connect to DB?

Thanks & Regards,
Sumit Desai