Скачать или смотреть Resolving Airflow + MySQL in Docker Compose: Fixing Unknown Host and Access Denied Issues

Discover how to solve common issues when setting up Airflow with MySQL in Docker Compose, including `unknown host` and `access denied` errors.
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This video is based on the question https://stackoverflow.com/q/68265805/ asked by the user 'Christie Chen' ( https://stackoverflow.com/u/7463965/ ) and on the answer https://stackoverflow.com/a/68269832/ provided by the user 'Jarek Potiuk' ( https://stackoverflow.com/u/516701/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Navigating Common Challenges with Airflow + MySQL in Docker Compose

Setting up an Airflow environment with MySQL as the backend can be challenging, especially for those new to Docker and these technologies. If you’re encountering issues like “unknown MySQL server host” or “access denied” errors, you’re not alone! Let's dive into these common problems and how to resolve them effectively.

Understanding the Problem

When trying to configure Airflow to work with MySQL in Docker Compose, users often face specific errors that hinder the setup process:

Unknown Host Error: This error typically arises when the application fails to locate the MySQL server. Instead of attempting to connect using an established container name, it might be trying an incorrect host.

Access Denied Error: This problem usually indicates that the provided credentials are not being accepted, which can happen when the authentication settings in the Docker container are not correctly configured.

In the case presented, the user faced multiple issues, including:

Connection string errors due to an incorrect host reference (mock_mysql).

Authentication issues with MySQL's health check.

The Solution Steps

1. Correcting the MySQL Hostname

The first step in resolving the unknown host error is to update the MySQL connection string in your airflow.cfg. You should replace the hostname:

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

with the appropriate service name as defined in your docker-compose.yml. In this case, change it to:

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

By doing this, you inform Airflow to connect to the MySQL service using the correct hostname defined in Docker Compose.

2. Configuring the Health Check Properly

The health check configuration in your docker-compose.yml is critical to ensure MySQL is ready before Airflow starts its services. The default behavior expects password-less access which can lead to complications if not configured correctly.

To fix the access denied error with the health check, make sure you pass the username and password as parameters. Edit the health check part like this:

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

This adjustment allows the health check to connect to MySQL using the correct credentials, enabling it to validate the service's availability properly.

3. Review Your Init SQL Script

Double-check the init SQL script to ensure it creates the database and user correctly. Here’s the basic structure you should follow:

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

Notice the change of localhost to %, which allows access from any host, crucial for containerized environments.

Conclusion

Setting up Airflow with MySQL using Docker Compose can present some challenges, but with careful attention to your configuration settings, you can overcome common issues like unknown hosts and access denied errors. Ensuring the correct service names and adjusting the authentication mechanisms will significantly improve your chances of successfully starting your Airflow services.

If you have any further questions or need additional guidance, don't hesitate to reach out!