Overview

Use environment variables to pass configuration information to containers at runtime.

Environment variables are key-value pairs that contain data that can be used by processes running inside a Docker container. They are often used to configure application settings and other parameters that may vary between different environments, such as development, testing, and production.

Tip

Before using environment variables, read through all of the information first to get a full picture of environment variables in Docker Compose.

This section covers:

• The various ways you can set environment variables with Compose.
• How environment variable precedence works.
• The correct syntax for an environment file.
• Changing pre-defined environment variables.
• Some best practices.