Cannot Connect to AWS RDS mysql database using Alembic

[fazal-kh4n]

Hi,

I am trying to use Alembic in my existing project. My current project uses an AWS RDS MySql database.

Using DBeaver, I can connect to the database fine using the following connection string:

I am now trying to set up Alembic in my project folder. To do this I ran the following commands:

• First:

alembic init alembic

• Second:

 from app import models
target_metadata = models.Base.metadata

• Third:
  alembic revision --autogenerate -m "gen"

However this throws the following error:

sqlalchemy.exc.OperationalError: (pymysql.err.OperationalError) (2003, "Can't connect to MySQL server on 'mydatabaseblahblah.rds.amazonaws.com' (timed out)"

In terms of my env.py file I have the following:

import json
import os

from forecast_integration.src.tables import Base
from logging.config import fileConfig

from sqlalchemy import engine_from_config
from sqlalchemy import pool

from alembic import context

def create_db_url():
    credentials = json.loads(os.environ['DB_SECRET'])

    return f"mysql+pymysql://{credentials['username']}:{credentials['password']}@{credentials['host']}:3306/{credentials['dbname']}"


# this is the Alembic Config object, which provides
# access to the values within the .ini file in use.
config = context.config


# Interpret the config file for Python logging.
# This line sets up loggers basically.
fileConfig(config.config_file_name)

# add your model's MetaData object here
# for 'autogenerate' support
# from myapp import mymodel
# target_metadata = mymodel.Base.metadata
target_metadata = Base.metadata

# other values from the config, defined by the needs of env.py,
# can be acquired:
# my_important_option = config.get_main_option("my_important_option")
# ... etc.
config.set_main_option('sqlalchemy.url', create_db_url())


def run_migrations_offline():
    """Run migrations in 'offline' mode.

    This configures the context with just a URL
    and not an Engine, though an Engine is acceptable
    here as well.  By skipping the Engine creation
    we don't even need a DBAPI to be available.

    Calls to context.execute() here emit the given string to the
    script output.

    """

    url = config.get_main_option("sqlalchemy.url")
    context.configure(
        url=url,
        target_metadata=target_metadata,
        literal_binds=True,
        dialect_opts={"paramstyle": "named"},
    )

    with context.begin_transaction():
        context.run_migrations()


def run_migrations_online():
    """Run migrations in 'online' mode.

    In this scenario we need to create an Engine
    and associate a connection with the context.

    """

    connectable = engine_from_config(
        config.get_section(config.config_ini_section),
        prefix="sqlalchemy.",
        poolclass=pool.NullPool,
    )

    with connectable.connect() as connection:
        context.configure(
            connection=connection, target_metadata=target_metadata
        )

        with context.begin_transaction():
            context.run_migrations()


if context.is_offline_mode():
    run_migrations_offline()
else:
    run_migrations_online()

My alembic.ini file:

# 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 = blah blah


[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

Can someone please explain how I may connect to AWS RDS MySql? I can't seem to see where I am going wrong.

Thanks.