Manually Running Alembic Migrations

Oct 13, 2025 by pynkocean.com 21 views

Connecting a new PostgreSQL (PSQL) instance to a DEV web service is a crucial step in ensuring seamless database operations. In this article, we will explore the process of manually running Alembic migrations, connecting Alembic and SQLAlchemy to DEV using PSQL username and password, and automatically running Alembic migrations as a predeploy step. Additionally, we will cover connecting Alembic and SQLAlchemy to DEV using Entrypoint ID.

Manually Running Alembic Migrations

To manually run Alembic migrations, you need to follow these steps:

Step 1: Install Alembic

Alembic is a lightweight, database-independent migration tool for Python. To install Alembic, run the following command in your terminal:

pip install alembic

Step 2: Initialize Alembic

To initialize Alembic, navigate to your project directory and run the following command:

alembic init alembic

This will create a new directory called alembic in your project directory.

Step 3: Configure Alembic

In the alembic.ini file, update the sqlalchemy.url parameter to point to your PSQL instance:

sqlalchemy.url = postgresql://username:password@localhost:5432/database

Replace username, password, localhost, 5432, and database with your actual PSQL credentials and instance details.

Step 4: Run Alembic Migrations

To run Alembic migrations, navigate to the alembic directory and run the following command:

alembic upgrade head

This will apply all the migrations up to the head revision.

Connecting Alembic and SQLAlchemy to DEV using PSQL Username and Password

To connect Alembic and SQLAlchemy to DEV using PSQL username and password, you need to follow these steps:

Step 1: Configure SQLAlchemy

In your application code, update the SQLALCHEMY_URL configuration variable to point to your PSQL instance:

SQLALCHEMY_URL = 'postgresql://username:password@localhost:5432/database'

Replace username, password, localhost, 5432, and database with your actual PSQL credentials and instance details.

Step 2: Configure Alembic

In the alembic.ini file, update the sqlalchemy.url parameter to point to your PSQL instance:

sqlalchemy.url = postgresql://username:password@localhost:5432/database

Replace username, password, localhost, 5432, and database with your actual PSQL credentials and instance details.

Automatically Running Alembic Migrations as a Predeploy Step

To automatically run Alembic migrations as a predeploy step, you need to follow these steps:

Step 1: Create a Predeploy Script

Create a new script called predeploy.sh in your project directory:

#!/bin/bash

alembic upgrade head

Make the script executable by running the following command:

chmod +x predeploy.sh

Step 2: Add the Predeploy Script to Your Deployment Process

Add the predeploy.sh script to your deployment process. For example, if you are using a tool like Ansible, you can add the script to the predeploy task:

predeploy:
  script: predeploy.sh

Connecting Alembic to DEV using Entrypoint ID

To connect Alembic to DEV using Entrypoint ID, you need to follow these steps:

Step 1: Configure Entrypoint

In your entrypoint.sh file, update the ALEMBIC_URL environment variable to point to your PSQL instance:

export ALEMBIC_URL='postgresql://username:password@localhost:5432/database'

Replace username, password, localhost, 5432, and database with your actual PSQL credentials and instance details.

Step 2: Configure Alembic

In the alembic.ini file, update the sqlalchemy.url parameter to point to your PSQL instance:

sqlalchemy.url = ${ALEMBIC_URL}

Connecting SQLAlchemy to DEV using Entrypoint ID

To connect SQLAlchemy to DEV using Entrypoint ID, you need to follow these steps:

Step 1: Configure Entrypoint

In your entrypoint.sh file, update the SQLALCHEMY_URL environment variable to point to your PSQL instance:

export SQLALCHEMY_URL='postgresql://username:password@localhost:5432/database'

Replace username, password, localhost, 5432, and database with your actual PSQL credentials and instance details.

Step 2: Configure SQLAlchemy

In your application code, update the SQLALCHEMY_URL configuration variable to point to your PSQL instance:

SQLALCHEMY_URL = os.environ['SQLALCHEMY_URL']

Connecting a new PostgreSQL (PSQL) instance to a DEV web service can be a complex process. In this article, we will answer some frequently asked questions about connecting Alembic and SQLAlchemy to DEV using PSQL username and password, and automatically running Alembic migrations as a predeploy step.

Q: What is Alembic and why do I need it?

A: Alembic is a lightweight, database-independent migration tool for Python. It is used to manage database schema changes by creating and applying migrations. You need Alembic to manage database schema changes and ensure that your application is always running with the latest database schema.

Q: How do I manually run Alembic migrations?

A: To manually run Alembic migrations, you need to follow these steps:

Install Alembic using pip: pip install alembic
Initialize Alembic: alembic init alembic
Configure Alembic: update the sqlalchemy.url parameter in the alembic.ini file to point to your PSQL instance
Run Alembic migrations: alembic upgrade head

Q: How do I connect Alembic and SQLAlchemy to DEV using PSQL username and password?

A: To connect Alembic and SQLAlchemy to DEV using PSQL username and password, you need to follow these steps:

Configure SQLAlchemy: update the SQLALCHEMY_URL configuration variable to point to your PSQL instance
Configure Alembic: update the sqlalchemy.url parameter in the alembic.ini file to point to your PSQL instance

Q: How do I automatically run Alembic migrations as a predeploy step?

A: To automatically run Alembic migrations as a predeploy step, you need to follow these steps:

Create a predeploy script: create a new script called predeploy.sh in your project directory
Add the predeploy script to your deployment process: add the script to your deployment process, such as Ansible

Q: How do I connect Alembic to DEV using Entrypoint ID?

A: To connect Alembic to DEV using Entrypoint ID, you need to follow these steps:

Configure Entrypoint: update the ALEMBIC_URL environment variable in the entrypoint.sh file to point to your PSQL instance
Configure Alembic: update the sqlalchemy.url parameter in the alembic.ini file to point to your PSQL instance

Q: How do I connect SQLAlchemy to DEV using Entrypoint ID?

A: To connect SQLAlchemy to DEV using Entrypoint ID, you need to follow these steps:

Configure Entrypoint: update the SQLALCHEMY_URL environment variable in the entrypoint.sh file to point to your PSQL instance
Configure SQLAlchemy: update the SQLALCHEMY_URL configuration variable to point to your PSQL instance

Q: What are the benefits of using Alembic and SQLAlchemy?

A: The benefits of using Alembic and SQLAlchemy include:

Easy management of database schema changes
Automatic application of migrations
Support for multiple database engines
Easy integration with other Python frameworks

Q: What are the common issues that I may encounter when connecting Alembic and SQLAlchemy to DEV?

A: Some common issues that you may encounter when connecting Alembic and SQLAlchemy to DEV include:

Incorrect configuration of Alembic and SQLAlchemy
Incompatible database engines
Missing dependencies
Incorrect usage of Alembic and SQLAlchemy commands

By following these Q&A, you can successfully connect your new PSQL instance to your DEV web service using Alembic and SQLAlchemy. Additionally, you can automatically run Alembic migrations as a predeploy step and connect Alembic and SQLAlchemy to DEV using Entrypoint ID.