Скачать или смотреть How to Connect Django Project to a Containerized PostgreSQL Database

Learn how to troubleshoot your `Django` connection to a `PostgreSQL` database running in a Docker container, resolve common errors, and ensure a successful integration.
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This video is based on the question https://stackoverflow.com/q/77636824/ asked by the user 'epsilon' ( https://stackoverflow.com/u/13113400/ ) and on the answer https://stackoverflow.com/a/77641533/ provided by the user 'ABWassim' ( https://stackoverflow.com/u/23045736/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Connecting Your Django Project to a Containerized PostgreSQL Database

Setting up a Django project with a PostgreSQL database running inside a Docker container can be a bit tricky, especially if you're facing connection errors. One common error message users encounter is: "django.db.utils.OperationalError: connection failed: port 5432 failed: FATAL: role 'demo' does not exist." How do you resolve this issue? Let’s dive into the solution step by step!

Understanding the Problem

When you attempt to connect your Django application to a PostgreSQL instance running in Docker, several moving parts must work seamlessly together, including your Django settings, the .env configuration, and the Docker setup.

In this scenario, the key components of your setup are as follows:

.env File

This file specifies the environment variables crucial for configuring the database connection:

[[See Video to Reveal this Text or Code Snippet]]

docker-compose.yml

This file defines the Docker services, including the PostgreSQL database:

[[See Video to Reveal this Text or Code Snippet]]

settings.py

This Django file contains the database connection settings:

[[See Video to Reveal this Text or Code Snippet]]

Steps to Troubleshoot Your Connection

Step 1: Check for Existing Services

It's essential to ensure that there are no other services already using port 5432, which could lead to connection conflicts:

Open your terminal and run:

[[See Video to Reveal this Text or Code Snippet]]

This command will list any processes that are occupying port 5432. If an old PostgreSQL instance is found, stop that service.

Step 2: Clear Old Data

If there were configuration changes or if you suspect that old data might be causing the issue, you might need to clear the existing data from your PostgreSQL Docker instance:

Navigate to your project directory.

Delete the existing postgres_data volume:

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Restart your services:

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Step 3: Verify Your Role Exists

The error you’re encountering suggests that the PostgreSQL role (demo) doesn’t exist. After restarting your container, connect to the PostgreSQL command line tool to verify:

Access the PostgreSQL shell:

[[See Video to Reveal this Text or Code Snippet]]

Check existing roles:

[[See Video to Reveal this Text or Code Snippet]]

Look for the role named demo. If it doesn’t exist:

[[See Video to Reveal this Text or Code Snippet]]

Step 4: Ensuring Configuration Consistency

Make sure that:

Your .env variables match exactly what you are using in settings.py.

Your Docker container is properly linked to your Django app, and the correct ports are being exposed.

Conclusion

Integrating a Django project with a containerized PostgreSQL database requires meticulous attention to configuration details. By following the steps outlined above, you should be able to solve most common connection issues.

Now, you’re well on your way to successfully connecting your Django application to a PostgreSQL database hosted in a Docker container. Happy coding!