[Python] Alembic Revisions for IBM DB2 not working

I am about to develop a web application using flask and ibm db for z/os. As now I am implementing with flask. I tried with this below approach. I have installed alembic and created alembic folder with its command and made some changes. I ran the initial migration file command and generated a version file, while doing alembic upgrade command, it iOS not applying any schema to db. I debugged and put a pdf in run migration online method and execution is not coming there, what am I missing.

I have modified my initial migration version to this. version/initial_migration.py

"""Initial migration

Revision ID: 41d53738262c
Revises:
Create Date: 2025-01-24 12:52:13.477580

"""
from alembic import op
import sqlalchemy as sa
# from src.utilities.all_envs import all_envs

# revision identifiers, used by Alembic.
revision = '41d53738262c'
down_revision = None
branch_labels = None
depends_on = None

def upgrade():
# Create the employee table
op.create_table(
'employee_table',
sa.Column('n_id', sa.Integer(), nullable=False),
sa.Column('v_name', sa.String(length=128), nullable=False),
sa.Column('v_description', sa.String(length=512), nullable=True),
sa.Column('v_other_names', sa.String(length=1024), nullable=True),

sa.PrimaryKeyConstraint('n_id'),
sa.UniqueConstraint('v_name'),
schema='sample_schema'
)


def downgrade():
op.drop_table('employee_table', schema='sample_schema')


this is my env.py of alembic.

from alembic import context
from sqlalchemy import create_engine, pool

def run_migrations_online():
# Retrieve the database URL from alembic.ini
config = context.config
url = config.get_main_option("sqlalchemy.url")

# Create an engine from the database URL
engine = create_engine(url, poolclass=pool.NullPool)

# Connect to the database
with engine.connect() as connection:
# Configure Alembic context without passing target_metadata
context.configure(
connection=connection
)

# Use the connection to begin migrations
with connection.begin():
context.run_migrations()


this is my alembic.ini

# A generic, single database configuration.

[alembic]
# path to migration scripts
script_location = alembic

# template used to generate migration files
# file_template = %%(rev)s_%%(slug)s

# sys.path path, will be prepended to sys.path if present.
# defaults to the current working directory.
prepend_sys_path = .

# timezone to use when rendering the date within the migration file
# as well as the filename.
# If specified, requires the python-dateutil library that can be
# installed by adding `alembic[tz]` to the pip requirements
# string value is passed to dateutil.tz.gettz()
# leave blank for localtime
# timezone =

# max length of characters to apply to the
# "slug" field
# truncate_slug_length = 40

# set to 'true' to run the environment during
# the 'revision' command, regardless of autogenerate
# revision_environment = false

# set to 'true' to allow .pyc and .pyo files without
# a source .py file to be detected as revisions in the
# versions/ directory
# sourceless = false

# version location specification; This defaults
# to alembic/versions. When using multiple version
# directories, initial revisions must be specified with --version-path.
# The path separator used here should be the separator specified by "version_path_separator"
# version_locations = %(here)s/bar:%(here)s/bat:alembic/versions

# version path separator; As mentioned above, this is the character used to split
# version_locations. Valid values are:
#
# version_path_separator = :
# version_path_separator = ;
# version_path_separator = space
version_path_separator = os # default: use os.pathsep

# the output encoding used when revision files
# are written from script.py.mako
# output_encoding = utf-8

sqlalchemy.url = ibm_db_sa://userwd@hostort/db



[post_write_hooks]
# post_write_hooks defines scripts or Python functions that are run
# on newly generated revision scripts. See the documentation for further
# detail and examples

# format using "black" - use the console_scripts runner, against the "black" entrypoint
# hooks = black
# black.type = console_scripts
# black.entrypoint = black
# black.options = -l 79 REVISION_SCRIPT_FILENAME

# Logging configuration
[loggers]
keys = root,sqlalchemy,alembic

[handlers]
keys = console

[formatters]
keys = generic

[logger_root]
level = WARN
handlers = console
qualname =

[logger_sqlalchemy]
level = WARN
handlers =
qualname = sqlalchemy.engine

[logger_alembic]
level = INFO
handlers =
qualname = alembic

[handler_console]
class = StreamHandler
args = (sys.stderr,)
level = NOTSET
formatter = generic

[formatter_generic]
format = %(levelname)-5.5s [%(name)s] %(message)s
datefmt = %H:%M:%S


I am trying this POC. I am able to generate initial migration File with alembic revision command and it generated a version file. But when I try alembic upgrade command it is not applying any tables to my database. Any help here.

libraries versions:

alembic==1.9.0

Flask==3.1.0
Flask-Cors==5.0.0
Flask-HTTPAuth==4.8.0
Flask-JWT-Extended==4.7.1
Flask-RESTful==0.3.10
flask-swagger-ui==4.11.1
greenlet==3.1.1
gunicorn==23.0.0
ibm_db==3.2.3
ibm_db_sa==0.4.1
idna==3.10
importlib_metadata==8.6.1
iniconfig==2.0.0

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