Скачать или смотреть Understanding Docker Swarm Secrets: Why Use the Secrets Path Instead of the Value

Discover why Docker Swarm uses the secrets path like `/run/secrets/` instead of values directly and how to correctly implement secrets in your Docker services.
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Understanding Docker Swarm Secrets: Why Use the Secrets Path Instead of the Value

When working with Docker Swarm, managing sensitive information like database passwords can be a challenge. One common question that often arises is: Why does Docker Swarm utilize the secrets path, such as /run/secrets/my_mysql_wordpress_password, instead of using the actual secrets value directly? This question is crucial for preventing security misconfigurations while ensuring that your applications can access the required credentials seamlessly. Let’s delve deeper into this topic and provide clarity on how to use Docker Swarm secrets effectively.

The Challenge with Secrets in Docker Swarm

You may have encountered an issue where, after setting your secrets in Docker Swarm, your application cannot connect to the database because it's trying to use the secrets path instead of the secret's value. Here’s a brief outline of the problem:

You've created secrets using the command:

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

After deploying your stack with the secrets referenced in your mysql.yml like so:

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

Instead of connecting to the database with the root password "password2", it shows as /run/secrets/my_mysql_root_password.

Why Does this Happen?

In Docker Swarm, secrets are designed to enhance the security of sensitive data. Here’s what’s happening in your setup:

Secrets Management: Docker Swarm is intended to handle secrets more securely by not exposing them directly in the environment variables. Instead of dynamically reading the secret’s value into the environment variable, it provides a path to the secret.

Reading Secrets: When using paths like /run/secrets/my_secret, the application expects to read from that file directly. Thus, using /run/secrets/my_mysql_root_password assigns the path to the environment variable instead of the value contained in the secret.

The Solution: Using *_FILE Suffix

The fix to this issue is straightforward. Instead of placing the secrets path directly into the environment variables, you should append _FILE to the variable names. Here’s how you can implement the solution:

Updated Docker Compose File

Modify your mysql.yml file to use the *_FILE suffix as follows:

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

Key Changes Made

Changed MYSQL_PASSWORD to MYSQL_PASSWORD_FILE and MYSQL_ROOT_PASSWORD to MYSQL_ROOT_PASSWORD_FILE.

This allows the MariaDB image to properly read the password values from the mounted secret files rather than interpreting the paths as literal strings.

Conclusion

By understanding and implementing the _FILE suffix in your environment variables related to Docker Swarm secrets, you can ensure that your application pulls the actual secret values securely and effectively. Docker Swarm’s design choice to utilize paths rather than direct values plays a crucial role in enhancing security, safeguarding your sensitive data from unnecessary exposure.

Implement these changes in your configuration, and you should be able to connect to your database without issues. This approach not only adheres to best practices for security but also makes your application more robust and scalable in a production environment.