Docker Env Vars in Practice

Environment variables are the simplest way to configure containers without rebuilding images — but Docker gives you multiple ways to inject them, and it’s easy to end up with a setup that’s brittle (or leaks secrets into image layers, logs, or repos).

In the full guide, we cover:

• The main ways to pass env vars into containers (-e/--env, --env-file, and Docker Compose)
• The difference between image defaults (ENV) and runtime configuration
• How to manage env vars cleanly across environments (dev/staging/prod)
• Best practices for safety and maintainability (especially when values are sensitive)

➡️ Read the full article on our blog:

https://spacelift.io/blog/docker-run-environment-variables