How to use Docker Secrets for secure management of sensitive data in Swarm mode?

Managing passwords, access tokens, and private keys in containers requires increased attention to security. Regular environment variables are easy to read through container inspection or accidentally compromised in a version control system. To solve this problem, Docker has a built-in secrets mechanism that encrypts data during storage and transmission.

Secrets only work in Docker Swarm mode and are delivered to containers via a secure in-memory filesystem. This means that the secret file is not written to the host disk and is inaccessible to other processes. When creating a secret, you pass its name and value via the terminal or a configuration file.

To create a new secret, a simple command is used in the terminal. For example, you can create a secret with a database name and pass it a text value or a file with a key. After that, the secret becomes available for binding to specific services in your cluster.

For a running service to use a secret, it must be explicitly specified in the deployment settings. Inside the container, the secret is automatically mounted to a special directory in RAM. The application can read this file using standard means of its programming language.

Using secrets significantly increases the overall infrastructure security. Developers no longer need to transmit credentials in plaintext or store them in Dockerfiles. This is an industry standard for creating reliable microservice applications in Docker.